The Shishi Manual

Shishi

Copyright © 2002, 2003 Simon Josefsson.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Sections, with the Front-Cover texts being "A GNU Manual," and with the Back-Cover Texts as in (a) below. A copy of the license is included in the section entitled "GNU Free Documentation License."

(a) The FSF's Back-Cover Text is: "You have freedom to copy and modify this GNU Manual, like GNU software. Copies published by the Free Software Foundation raise funds for GNU development."

• Introduction: How to use this manual.
• User Manual: Using Shishi as end-user.
• Administration Manual: Administrating server aspects of Shishi.
• Reference Manual: Detailed description of config files, etc.
• Programming Manual: Calling Shishi from a programming language.
• Acknowledgements: Whom to blame.

  Appendices

• Copying This Manual: How you can copy and share this manual.
• Copying: How you can copy and share the source.

  Indices

• Concept Index: Index of concepts and programs.
• Function and Data Index: Index of functions, variables and data types.

1 Introduction

Shishi implements the Kerberos 5 network security system.

• Getting Started:
• Features and Status:
• Overview:
• Cryptographic Overview:
• Supported Platforms:
• Downloading and Installing:
• Bug Reports:
• Contributing:

1.1 Getting Started

This manual documents the Shishi application and library programming interface. All commands, functions and data types provided by Shishi are explained.

The reader is assumed to possess basic familiarity with network security and the Kerberos 5 security system.

This manual can be used in several ways. If read from the beginning to the end, it gives a good introduction into the library and how it can be used in an application. Forward references are included where necessary. Later on, the manual can be used as a reference manual to get just the information needed about any particular interface of the library. Experienced programmers might want to start looking at the examples at the end of the manual, and then only read up those parts of the interface which are unclear.

1.2 Features and Status

Shishi might have a couple of advantages over other packages doing a similar job.

It's Free Software

Anybody can use, modify, and redistribute it under the terms of the GNU General Public License (see Copying).

It's thread-safe

The library uses no global variables.

It's internationalized

It handles non-ASCII username and passwords and user visible strings used in the library (error messages) can be translated into the users' language.

It's portable

It should work on all Unix like operating systems, including Windows.

Shishi is far from feature complete, it is not even a full RFC 1510 implementation yet. However, some basic functionality is implemented. A few implemented feature are mentioned below.

• Initial authentication (AS) from raw key or password. This step is typically used to acquire a ticket granting ticket and, less commonly, a server ticket.
• Subsequent authentication (TGS). This step is typically used to acquire a server ticket, by authenticating yourself using the ticket granting ticket.
• Client-Server authentication (AP). This step is used by clients and servers to prove to each other who they are, using negotiated tickets.
• Integrity protected communication (SAFE). This step is used by clients and servers to exchange integrity protected data with each other. The key is typically agreed on using the Client-Server authentication step.
• Ticket cache, supporting multiple principals and realms. As tickets have a life time of typically several hours, they are managed in disk files. There can be multiple ticket caches, and each ticket cache can store tickets for multiple clients (users), servers, encryption types, etc. Functionality is provided for locating the proper ticket for every use.
• Most standard cryptographic primitives. The believed most secure algorithms are supported (see Cryptographic Overview).
• Telnet client and server. This is used to remotely login to other machines, after authenticating yourself with a ticket.
• PAM module. This is used to login locally on a machine.
• KDC addresses located using DNS SRV RRs.
• Modularized low-level crypto interface. Currently Nettle and Libgcrypt are supported. If you wish to add support for another low-level cryptographic library, you only have to implement a few APIs to DES, AES, MD5, SHA1, HMAC, etc, look at lib/nettle.c or lib/libgcrypt.c as a starting pointer.

The following table summarize what the current objectives are (i.e., the todo list) and an estimate on how long it will take to implement the feature. If you like to start working on anything, please let me know so work duplication can be avoided.

• Pre-authentication support (week).
• Cross-realm support (week).
• PKINIT (use libksba, weeks)
• Finish GSSAPI support via GSSLib (weeks) Shishi will not support GSSLib natively, but a separate project "GSSLib" is under way to produce a generic GSS implementation, and it will use Shishi to implement the Kerberos 5 mechanism.
• Port to cyclone (cyclone need to mature first)
• Modularize ASN.1 library so it can be replaced (days). Almost done, all ASN.1 functionality is found in lib/asn1.c, although the interface is rather libtasn1 centric.
• KDC (initiated, weeks)
• Set/Change password protocol (weeks?)
• Port applications to use Shishi (indefinite)
• Improve documentation
• Improve internationalization
• Add AP-REQ replay cache (week).
• Study benefits by introducing a PA-TGS-REP. This would provide mutual authentication of the KDC in a way that is easier to analyze. Currently the mutual authentication property is only implicit from successful decryption of the KDC-REP and the 4 byte nonce.
• GUI applet for managing tickets.

1.3 Overview

This section describes RFC 1510 from a protocol point of view¹.

Kerberos provides a means of verifying the identities of principals, (e.g., a workstation user or a network server) on an open (unprotected) network. This is accomplished without relying on authentication by the host operating system, without basing trust on host addresses, without requiring physical security of all the hosts on the network, and under the assumption that packets traveling along the network can be read, modified, and inserted at will. (Note, however, that many applications use Kerberos' functions only upon the initiation of a stream-based network connection, and assume the absence of any "hijackers" who might subvert such a connection. Such use implicitly trusts the host addresses involved.) Kerberos performs authentication under these conditions as a trusted third- party authentication service by using conventional cryptography, i.e., shared secret key. (shared secret key - Secret and private are often used interchangeably in the literature. In our usage, it takes two (or more) to share a secret, thus a shared DES key is a secret key. Something is only private when no one but its owner knows it. Thus, in public key cryptosystems, one has a public and a private key.)

The authentication process proceeds as follows: A client sends a request to the authentication server (AS) requesting "credentials" for a given server. The AS responds with these credentials, encrypted in the client's key. The credentials consist of 1) a "ticket" for the server and 2) a temporary encryption key (often called a "session key"). The client transmits the ticket (which contains the client's identity and a copy of the session key, all encrypted in the server's key) to the server. The session key (now shared by the client and server) is used to authenticate the client, and may optionally be used to authenticate the server. It may also be used to encrypt further communication between the two parties or to exchange a separate sub-session key to be used to encrypt further communication.

The implementation consists of one or more authentication servers running on physically secure hosts. The authentication servers maintain a database of principals (i.e., users and servers) and their secret keys. Code libraries provide encryption and implement the Kerberos protocol. In order to add authentication to its transactions, a typical network application adds one or two calls to the Kerberos library, which results in the transmission of the necessary messages to achieve authentication.

The Kerberos protocol consists of several sub-protocols (or exchanges). There are two methods by which a client can ask a Kerberos server for credentials. In the first approach, the client sends a cleartext request for a ticket for the desired server to the AS. The reply is sent encrypted in the client's secret key. Usually this request is for a ticket-granting ticket (TGT) which can later be used with the ticket-granting server (TGS). In the second method, the client sends a request to the TGS. The client sends the TGT to the TGS in the same manner as if it were contacting any other application server which requires Kerberos credentials. The reply is encrypted in the session key from the TGT.

Once obtained, credentials may be used to verify the identity of the principals in a transaction, to ensure the integrity of messages exchanged between them, or to preserve privacy of the messages. The application is free to choose whatever protection may be necessary.

To verify the identities of the principals in a transaction, the client transmits the ticket to the server. Since the ticket is sent "in the clear" (parts of it are encrypted, but this encryption doesn't thwart replay) and might be intercepted and reused by an attacker, additional information is sent to prove that the message was originated by the principal to whom the ticket was issued. This information (called the authenticator) is encrypted in the session key, and includes a timestamp. The timestamp proves that the message was recently generated and is not a replay. Encrypting the authenticator in the session key proves that it was generated by a party possessing the session key. Since no one except the requesting principal and the server know the session key (it is never sent over the network in the clear) this guarantees the identity of the client.

The integrity of the messages exchanged between principals can also be guaranteed using the session key (passed in the ticket and contained in the credentials). This approach provides detection of both replay attacks and message stream modification attacks. It is accomplished by generating and transmitting a collision-proof checksum (elsewhere called a hash or digest function) of the client's message, keyed with the session key. Privacy and integrity of the messages exchanged between principals can be secured by encrypting the data to be passed using the session key passed in the ticket, and contained in the credentials.

1.4 Cryptographic Overview

Shishi implements several of the standard cryptographic primitives. In this section we give the names of the supported encryption suites, and some notes about them, and their associated checksum suite.

Statements such as "it is weak" should be read as meaning that there is no credible security analysis of the mechanism available, and/or that should an attack be published publicly, few people would likely be surprised. Also keep in mind that the key size mentioned is the actual key size, not the effective key space as far as a brute force attack is concerned.

NULL

NULL is a dummy encryption suite for debugging. Encryption and decryption are identity functions. No integrity protection. It is weak. It is associated with the NULL checksum.

arcfour-hmac

arcfour-hmac-exp

arcfour-hmac-* are a proprietary stream cipher with 56 bit (arcfour-hmac-exp) or 128 bit (arcfour-hmac) keys, used in a proprietary way described in an expired IETF draft draft-brezak-win2k-krb-rc4-hmac-04.txt. Deriving keys from passwords is supported, and is done by computing a message digest (MD4) of a 16-bit Unicode representation of the ASCII password, with no salt. Data is integrity protected with a keyed hash (HMAC-MD5), where the key is derived from the base key in a creative way. It is weak. It is associated with the arcfour-hmac-md5 checksum.

des-cbc-crc

des-cbc-crc is DES encryption and decryption with 56 bit keys and 8 byte blocks in CBC mode, using the key as IV. The keys can be derived from passwords by an obscure application specific algorithm. Data is integrity protected with an unkeyed but encrypted CRC32-like checksum. It is weak. It is associated with the rsa-md5-des checksum.

des-cbc-md4

des-cbc-md4 is DES encryption and decryption with 56 bit keys and 8 byte blocks in CBC mode, using a zero IV. The keys can be derived from passwords by an obscure application specific algorithm. Data is integrity protected with an unkeyed but encrypted MD4 hash. It is weak. It is associated with the rsa-md4-des checksum.

des-cbc-md5

des-cbc-md5 is DES encryption and decryption with 56 bit keys and 8 byte blocks in CBC mode, using a zero IV. The keys can be derived from passwords by an obscure application specific algorithm. Data is integrity protected with an unkeyed but encrypted MD5 hash. It is weak. It is associated with the rsa-md5-des checksum. This is the strongest RFC 1510 interoperable encryption mechanism.

des3-cbc-sha1-kd

des3-cbc-sha1-kd is DES encryption and decryption with three 56 bit keys (effective key size 112 bits) and 8 byte blocks in CBC mode. The keys can be derived from passwords by a algorithm based on the paper "A Better Key Schedule For DES-like Ciphers" ² by Uri Blumenthal and Steven M. Bellovin (it is not clear if the algorithm, and the way it is used, is used by any other protocols, although it seems unlikely). Data is integrity protected with a keyed SHA1 hash in HMAC mode. It has no security proof, but is assumed to provide adequate security in the sense that knowledge on how to crack it is not known to the public. Note that the key derivation function is not widely used outside of Kerberos, hence not widely studied. It is associated with the hmac-sha1-des3-kd checksum.

aes128-cts-hmac-sha1-96

aes256-cts-hmac-sha1-96

aes128-cts-hmac-sha1-96 and aes256-cts-hmac-sha1-96 is AES encryption and decryption with 128 bit and 256 bit key, respectively, and 16 byte blocks in CBC mode with Cipher Text Stealing. Cipher Text Stealing means data length of encrypted data is preserved (pure CBC add up to 7 pad characters). The keys can be derived from passwords with RSA Laboratories PKCS#5 Password Based Key Derivation Function 2³, which is allegedly provably secure in a random oracle model. Data is integrity protected with a keyed SHA1 hash, in HMAC mode, truncated to 96 bits. There is no security proof, but the schemes are assumed to provide adequate security in the sense that knowledge on how to crack them is not known to the public. Note that AES has yet to receive the test of time, and the CBC variation used is not widely standardized (hence not widely studied). It is associated with the hmac-sha1-96-aes128 and hmac-sha1-96-aes256 checksums, respectively.

The protocol do not include any way to negotiate which checksum mechanisms to use, so in most cases the associated checksum will be used. However, checksum mechanisms can be used with other encryption mechanisms, as long as they are compatible in terms of key format etc. Here are the names of the supported checksum mechanisms, with some notes on their status and the compatible encryption mechanisms. They are ordered by increased security as perceived by the author.

NULL

NULL is a dummy checksum suite for debugging. It provides no integrity. It is weak. It is compatible with the NULL encryption mechanism.

arcfour-hmac-md5

arcfour-hmac-md5 is a keyed HMAC-MD5 checksum computed on a MD5 message digest, in turn computed on a four byte message type indicator concatenated with the application data. (The arcfour designation is thus somewhat misleading, but since this checksum mechanism is described in the same document as the arcfour encryption mechanisms, it is not a completely unnatural designation.) It is weak. It is compatible with all encryption mechanisms.

rsa-md4

rsa-md4 is a unkeyed MD4 hash computed over the message. Since it is unkeyed, it is in general a weak checksum, however applications can, with care, use it non-weak ways (e.g., by including the hash in other messages that are encrypted or checksummed). It is compatible with all encryption mechanisms.

rsa-md4-des

rsa-md4-des is a DES CBC encryption of one block of random data and a unkeyed MD4 hash computed over the random data and the message to integrity protect. The key used is derived from the base protocol key by XOR with a constant. It is weak. It is compatible with the des-cbc-crc, des-cbc-md4, des-cbc-md5 encryption mechanisms.

rsa-md5

rsa-md5 is a unkeyed MD5 hash computed over the message. Since it is unkeyed, it is in general a weak checksum, however applications can, with care, use it non-weak ways (e.g., by including the hash in other messages that are encrypted or checksummed). It is compatible with all encryption mechanisms.

rsa-md5-des

rsa-md5-des is a DES CBC encryption of one block of random data and a unkeyed MD5 hash computed over the random data and the message to integrity protect. The key used is derived from the base protocol key by XOR with a constant. It is weak. It is compatible with the des-cbc-crc, des-cbc-md4, des-cbc-md5 encryption mechanisms.

hmac-sha1-des3-kd

hmac-sha1-des3-kd is a keyed SHA1 hash in HMAC mode computed over the message. The key is derived from the base protocol by the simplified key derivation function (similar to the password key derivation functions of des3-cbc-sha1-kd). It has no security proof, but is assumed to provide good security, if the key derivation function is good. It is compatible with the des3-cbc-sha1-kd encryption mechanism.

hmac-sha1-96-aes128

hmac-sha1-96-aes256

hmac-sha1-96-aes* are keyed SHA1 hashes in HMAC mode computed over the message and then truncated to 96 bits. The key is derived from the base protocol by the simplified key derivation function (similar to the password key derivation functions of des3-cbc-sha1-kd). It has no security proof, but is assumed to provide good security, if the key derivation function is good. It is compatible with the aes*-cts-hmac-sha1-96 encryption mechanisms.

Several of the cipher suites have long names that can be hard to memorize. For your convenience, the following short-hand aliases exists.

arcfour

Alias for arcfour-hmac.

des-crc

Alias for des-cbc-crc.

des-md4

Alias for des-cbc-md4.

des-md5

des

Alias for des-cbc-md5.

des3

3des

Alias for des3-cbc-sha1-kd.

aes128

Alias for aes128-cts-hmac-sha1-96.

aes

aes256

Alias for aes256-cts-hmac-sha1-96.

1.5 Supported Platforms

Shishi has at some point in time been tested on the following platforms. Online build reports for each platforms and Shishi version is available at <http://josefsson.org/autobuild/>.

1. Debian GNU/Linux 3.0 (Woody)

   GCC 2.95.4 and GNU Make. This is the main development platform. alphaev67-unknown-linux-gnu, alphaev6-unknown-linux-gnu, arm-unknown-linux-gnu, armv4l-unknown-linux-gnu, hppa-unknown-linux-gnu, hppa64-unknown-linux-gnu, i686-pc-linux-gnu, ia64-unknown-linux-gnu, m68k-unknown-linux-gnu, mips-unknown-linux-gnu, mipsel-unknown-linux-gnu, powerpc-unknown-linux-gnu, s390-ibm-linux-gnu, sparc-unknown-linux-gnu, sparc64-unknown-linux-gnu.

2. Debian GNU/Linux 2.1

   GCC 2.95.4 and GNU Make. armv4l-unknown-linux-gnu.

3. Tru64 UNIX

   Tru64 UNIX C compiler and Tru64 Make. alphaev67-dec-osf5.1, alphaev68-dec-osf5.1.

4. SuSE Linux 7.1

   GCC 2.96 and GNU Make. alphaev6-unknown-linux-gnu, alphaev67-unknown-linux-gnu.

5. SuSE Linux 7.2a

   GCC 3.0 and GNU Make. ia64-unknown-linux-gnu.

6. SuSE Linux

   GCC 3.2.2 and GNU Make. x86_64-unknown-linux-gnu (AMD64 Opteron "Melody").

7. RedHat Linux 7.2

   GCC 2.96 and GNU Make. alphaev6-unknown-linux-gnu, alphaev67-unknown-linux-gnu, ia64-unknown-linux-gnu.

8. RedHat Linux 8.0

   GCC 3.2 and GNU Make. i686-pc-linux-gnu.

9. RedHat Advanced Server 2.1

   GCC 2.96 and GNU Make. i686-pc-linux-gnu.

10. Slackware Linux 8.0.01

    GCC 2.95.3 and GNU Make. i686-pc-linux-gnu.

11. Mandrake Linux 9.0

    GCC 3.2 and GNU Make. i686-pc-linux-gnu.

12. IRIX 6.5

    MIPS C compiler, IRIX Make. mips-sgi-irix6.5.

13. AIX 4.3.2

    IBM C for AIX compiler, AIX Make. rs6000-ibm-aix4.3.2.0.

14. HP-UX 11

    HP-UX C compiler and HP Make. ia64-hp-hpux11.22, hppa2.0w-hp-hpux11.11.

15. SUN Solaris 2.8

    Sun WorkShop Compiler C 6.0 and SUN Make. sparc-sun-solaris2.8.

16. NetBSD 1.6

    GCC 2.95.3 and GNU Make. alpha-unknown-netbsd1.6, i386-unknown-netbsdelf1.6.

17. OpenBSD 3.1 and 3.2

    GCC 2.95.3 and GNU Make. alpha-unknown-openbsd3.1, i386-unknown-openbsd3.1.

18. FreeBSD 4.7 and 4.8

    GCC 2.95.4 and GNU Make. alpha-unknown-freebsd4.7, alpha-unknown-freebsd4.8, i386-unknown-freebsd4.7, i386-unknown-freebsd4.8.

19. MacOS X 10.2 Server Edition

    GCC 3.1 and GNU Make. powerpc-apple-darwin6.5.

If you use Shishi on, or port Shishi to, a new platform please report it to the author (see Bug Reports).

1.6 Downloading and Installing

The package can be downloaded from several places, including <http://josefsson.org/shishi/releases/>. The latest version is stored in a file, e.g., shishi-0.0.42.tar.gz where the 0.0.42 indicate the highest version number.

The package is then extracted, configured and built like many other packages that use Autoconf. For detailed information on configuring and building it, refer to the INSTALL file that is part of the distribution archive.

Here is an example terminal session that download, configure, build and install the package. You will need a few basic tools, such as sh, make and cc.

     $ wget -q http://josefsson.org/shishi/releases/shishi-0.0.4.tar.gz
     $ tar xfz shishi-0.0.4.tar.gz
     $ cd shishi-0.0.4/
     $ ./configure
     ...
     $ make
     ...
     $ make install
     ...
     

After this you should be prepared to continue with the user, administration or programming manual, depending on how you want to use Shishi.

1.7 Bug Reports

If you think you have found a bug in Shishi, please investigate it and report it.

• Please make sure that the bug is really in Shishi, and preferably also check that it hasn't already been fixed in the latest version.
• You have to send us a test case that makes it possible for us to reproduce the bug.
• You also have to explain what is wrong; if you get a crash, or if the results printed are not good and in that case, in what way. Make sure that the bug report includes all information you would need to fix this kind of bug for someone else.

Please make an effort to produce a self-contained report, with something definite that can be tested or debugged. Vague queries or piecemeal messages are difficult to act on and don't help the development effort.

If your bug report is good, we will do our best to help you to get a corrected version of the software; if the bug report is poor, we won't do anything about it (apart from asking you to send better bug reports).

If you think something in this manual is unclear, or downright incorrect, or if the language needs to be improved, please also send a note.

Send your bug report to:

1.8 Contributing

If you want to submit a patch for inclusion - from solve a typo you discovered, up to adding support for a new feature - you should submit it as a bug report (see Bug Reports). There are some things that you can do to increase the chances for it to be included in the official package.

Unless your patch is very small (say, under 10 lines) we require that you assign the copyright of your work to the Free Software Foundation. This is to protect the freedom of the project. If you have not already signed papers, we will send you the necessary information when you submit your contribution.

For contributions that doesn't consist of actual programming code, the only guidelines are common sense. Use it.

For code contributions, a number of style guides will help you:

• Coding Style. Follow the GNU Standards document (see GNU Coding Standards).

  If you normally code using another coding standard, there is no problem, but you should use indent to reformat the code (see GNU Indent) before submitting your work.

• Use the unified diff format diff -u.
• Return errors. The only valid reason for ever aborting the execution of the program is due to memory allocation errors, but for that you should call xalloc_die to allow the application to recover if it wants to.
• Design with thread safety in mind. Don't use global variables. Don't even write to per-handle global variables unless the documented behaviour of the function you write is to write to the per-handle global variable.
• Avoid using the C math library. It causes problems for embedded implementations, and in most situations it is very easy to avoid using it.
• Document your functions. Use comments before each function headers, that, if properly formatted, are extracted into Texinfo manuals and GTK-DOC web pages.
• Supply a ChangeLog and NEWS entries, where appropriate.

2 User Manual

Usually Shishi interacts with you to get some initial authentication information like a password, and then contacts a server to receive a so called ticket granting ticket. From now on, you rarely interacts with Shishi directly. Applications that needs security services instruct the Shishi library to use the ticket granting ticket to get new tickets for various servers. An example could be if you log on to a host remotely via telnet. The host usually requires authentication before permitting you in. The telnet client uses the ticket granting ticket to get a ticket for the server, and then use this ticket to authenticate you against the server (typically the server is also authenticated to you). You perform the initial authentication by typing shishi at the prompt. Sometimes it is necessary to supply options telling Shishi what your principal name (user name in the Kerberos realm) or realm is. In the example, I specify the client name simon@JOSEFSSON.ORG.

$ shishi simon@JOSEFSSON.ORG Enter password for `simon@JOSEFSSON.ORG': simon@JOSEFSSON.ORG: Authtime: Fri Aug 15 04:44:49 2003 Endtime: Fri Aug 15 05:01:29 2003 Server: krbtgt/JOSEFSSON.ORG key des3-cbc-sha1-kd (16) Ticket key: des3-cbc-sha1-kd (16) protected by des3-cbc-sha1-kd (16) Ticket flags: INITIAL (512) $

As you can see, Shishi also prints a short description of the ticket received.

A logical next step is to display all tickets you have received (by the way, the tickets are usually stored as text in ~/.shishi/tickets). This is achieved by typing shishi --list.

$ shishi --list Tickets in `/home/jas/.shishi/tickets': jas@JOSEFSSON.ORG: Authtime: Fri Aug 15 04:49:46 2003 Endtime: Fri Aug 15 05:06:26 2003 Server: krbtgt/JOSEFSSON.ORG key des-cbc-md5 (3) Ticket key: des-cbc-md5 (3) protected by des-cbc-md5 (3) Ticket flags: INITIAL (512) jas@JOSEFSSON.ORG: Authtime: Fri Aug 15 04:49:46 2003 Starttime: Fri Aug 15 04:49:49 2003 Endtime: Fri Aug 15 05:06:26 2003 Server: host/latte.josefsson.org key des-cbc-md5 (3) Ticket key: des-cbc-md5 (3) protected by des-cbc-md5 (3) 2 tickets found. $

As you can see, I had a ticket for the server host/latte.josefsson.org which was generated by telnet:ing to that host.

If, for some reason, you want to manually get a ticket for a specific server, you can use the shishi --server-name command. Normally, however, the application that uses Shishi will take care of getting a ticket for the appropriate server, so you normally wouldn't need this command.

$ shishi --server-name=user/billg --encryption-type=des-cbc-md4 jas@JOSEFSSON.ORG: Authtime: Fri Aug 15 04:49:46 2003 Starttime: Fri Aug 15 04:54:33 2003 Endtime: Fri Aug 15 05:06:26 2003 Server: user/billg key des-cbc-md4 (2) Ticket key: des-cbc-md4 (2) protected by des-cbc-md5 (3) $

As you can see, I acquired a ticket for user/billg with a des-cbc-md4 (see Cryptographic Overview) encryption key specified with the --encryption-type parameter.

To wrap up this introduction, lets see how you can remove tickets. You may want to do this if you leave your terminal for lunch or similar, and don't want someone to be able to copy the file and then use your credentials. Note that this only destroy the tickets locally, it does not contact any server and tell it that these credentials are no longer valid. So if someone stole your ticket file, you must contact your administrator and have them reset your account, simply using this parameter is not sufficient.

$ shishi --server-name=imap/latte.josefsson.org --destroy 1 ticket removed. $ shishi --server-name=foobar --destroy No tickets removed. $ shishi --destroy 3 tickets removed. $

Since the --server-name parameter takes a long to type, it is possible to type the server name directly, after the client name. The following example demonstrate a AS-REQ followed by a TGS-REQ for a specific server (assuming you did not have any tickets from the start).

$ src/shishi simon@latte.josefsson.org imap/latte.josefsson.org Enter password for `simon@latte.josefsson.org': simon@latte.josefsson.org: Acquired: Wed Aug 27 17:21:06 2003 Expires: Wed Aug 27 17:37:46 2003 Server: imap/latte.josefsson.org key aes256-cts-hmac-sha1-96 (18) Ticket key: aes256-cts-hmac-sha1-96 (18) protected by aes256-cts-hmac-sha1-96 (18) Ticket flags: FORWARDED PROXIABLE (12) $

Refer to the reference manual for all available parameters (see Parameters for shishi). The rest of this section contains description of more specialized usage modes that can be ignored by most users.

2.1 Proxiable and Proxy Tickets

At times it may be necessary for a principal to allow a service to perform an operation on its behalf. The service must be able to take on the identity of the client, but only for a particular purpose. A principal can allow a service to take on the principal's identity for a particular purpose by granting it a proxy.

The process of granting a proxy using the proxy and proxiable flags is used to provide credentials for use with specific services. Though conceptually also a proxy, users wishing to delegate their identity in a form usable for all purpose MUST use the ticket forwarding mechanism described in the next section to forward a ticket-granting ticket.

The PROXIABLE flag in a ticket is normally only interpreted by the ticket-granting service. It can be ignored by application servers. When set, this flag tells the ticket-granting server that it is OK to issue a new ticket (but not a ticket-granting ticket) with a different network address based on this ticket. This flag is set if requested by the client on initial authentication. By default, the client will request that it be set when requesting a ticket-granting ticket, and reset when requesting any other ticket.

This flag allows a client to pass a proxy to a server to perform a remote request on its behalf (e.g. a print service client can give the print server a proxy to access the client's files on a particular file server in order to satisfy a print request).

In order to complicate the use of stolen credentials, Kerberos tickets are usually valid from only those network addresses specifically included in the ticket[4]. When granting a proxy, the client MUST specify the new network address from which the proxy is to be used, or indicate that the proxy is to be issued for use from any address.

The PROXY flag is set in a ticket by the TGS when it issues a proxy ticket. Application servers MAY check this flag and at their option they MAY require additional authentication from the agent presenting the proxy in order to provide an audit trail.

Here is how you would acquire a PROXY ticket for the service imap/latte.josefsson.org:

$ shishi jas@JOSEFSSON.ORG imap/latte.josefsson.org --proxy Enter password for `jas@JOSEFSSON.ORG': libshishi: warning: KDC bug: Reply encrypted using wrong key. jas@JOSEFSSON.ORG: Authtime: Mon Sep 8 20:02:35 2003 Starttime: Mon Sep 8 20:02:36 2003 Endtime: Tue Sep 9 04:02:35 2003 Server: imap/latte.josefsson.org key des3-cbc-sha1-kd (16) Ticket key: des3-cbc-sha1-kd (16) protected by des3-cbc-sha1-kd (16) Ticket flags: PROXY (16) $

As you noticed, this asked for your password. The reason is that proxy tickets must be acquired using a proxiable ticket granting ticket, which was not present. If you often need to get proxy tickets, you may acquire a proxiable ticket granting ticket from the start:

$ shishi --proxiable Enter password for `jas@JOSEFSSON.ORG': jas@JOSEFSSON.ORG: Authtime: Mon Sep 8 20:04:27 2003 Endtime: Tue Sep 9 04:04:27 2003 Server: krbtgt/JOSEFSSON.ORG key des3-cbc-sha1-kd (16) Ticket key: des3-cbc-sha1-kd (16) protected by des3-cbc-sha1-kd (16) Ticket flags: PROXIABLE INITIAL (520)

Then you should be able to acquire proxy tickets based on that ticket granting ticket, as follows:

$ shishi jas@JOSEFSSON.ORG imap/latte.josefsson.org --proxy libshishi: warning: KDC bug: Reply encrypted using wrong key. jas@JOSEFSSON.ORG: Authtime: Mon Sep 8 20:04:27 2003 Starttime: Mon Sep 8 20:04:32 2003 Endtime: Tue Sep 9 04:04:27 2003 Server: imap/latte.josefsson.org key des3-cbc-sha1-kd (16) Ticket key: des3-cbc-sha1-kd (16) protected by des3-cbc-sha1-kd (16) Ticket flags: PROXY (16) $

2.2 Forwardable and Forwarded Tickets

Authentication forwarding is an instance of a proxy where the service that is granted is complete use of the client's identity. An example where it might be used is when a user logs in to a remote system and wants authentication to work from that system as if the login were local.

The FORWARDABLE flag in a ticket is normally only interpreted by the ticket-granting service. It can be ignored by application servers. The FORWARDABLE flag has an interpretation similar to that of the PROXIABLE flag, except ticket-granting tickets may also be issued with different network addresses. This flag is reset by default, but users MAY request that it be set by setting the FORWARDABLE option in the AS request when they request their initial ticket-granting ticket.

This flag allows for authentication forwarding without requiring the user to enter a password again. If the flag is not set, then authentication forwarding is not permitted, but the same result can still be achieved if the user engages in the AS exchange specifying the requested network addresses and supplies a password.

The FORWARDED flag is set by the TGS when a client presents a ticket with the FORWARDABLE flag set and requests a forwarded ticket by specifying the FORWARDED KDC option and supplying a set of addresses for the new ticket. It is also set in all tickets issued based on tickets with the FORWARDED flag set. Application servers may choose to process FORWARDED tickets differently than non-FORWARDED tickets.

If addressless tickets are forwarded from one system to another, clients SHOULD still use this option to obtain a new TGT in order to have different session keys on the different systems.

Here is how you would acquire a FORWARDED ticket for the service host/latte.josefsson.org:

$ shishi jas@JOSEFSSON.ORG host/latte.josefsson.org --forwarded Enter password for `jas@JOSEFSSON.ORG': libshishi: warning: KDC bug: Reply encrypted using wrong key. jas@JOSEFSSON.ORG: Authtime: Mon Sep 8 20:07:11 2003 Starttime: Mon Sep 8 20:07:12 2003 Endtime: Tue Sep 9 04:07:11 2003 Server: host/latte.josefsson.org key des3-cbc-sha1-kd (16) Ticket key: des3-cbc-sha1-kd (16) protected by des3-cbc-sha1-kd (16) Ticket flags: FORWARDED (4) $

As you noticed, this asked for your password. The reason is that forwarded tickets must be acquired using a forwardable ticket granting ticket, which was not present. If you often need to get forwarded tickets, you may acquire a forwardable ticket granting ticket from the start:

$ shishi --forwardable Enter password for `jas@JOSEFSSON.ORG': jas@JOSEFSSON.ORG: Authtime: Mon Sep 8 20:08:53 2003 Endtime: Tue Sep 9 04:08:53 2003 Server: krbtgt/JOSEFSSON.ORG key des3-cbc-sha1-kd (16) Ticket key: des3-cbc-sha1-kd (16) protected by des3-cbc-sha1-kd (16) Ticket flags: FORWARDABLE INITIAL (514) $

Then you should be able to acquire forwarded tickets based on that ticket granting ticket, as follows:

$ shishi jas@JOSEFSSON.ORG host/latte.josefsson.org --forwarded libshishi: warning: KDC bug: Reply encrypted using wrong key. jas@JOSEFSSON.ORG: Authtime: Mon Sep 8 20:08:53 2003 Starttime: Mon Sep 8 20:08:57 2003 Endtime: Tue Sep 9 04:08:53 2003 Server: host/latte.josefsson.org key des3-cbc-sha1-kd (16) Ticket key: des3-cbc-sha1-kd (16) protected by des3-cbc-sha1-kd (16) Ticket flags: FORWARDED (4) $

3 Administration Manual

This section describe how you get the KDC server up and running to answer queries from clients.

First you must create a user database. Currently this is rather simplistic, and the database only contains cryptographic keys. Use the shishi --string-to-key command to generate keys, and store them in the shishid.keys file. The file path is /usr/local/etc/shishid.keys by default, although you can use shishid -k to specify another location.

Create a random key for the Kerberos Ticket Granting Service for your realm:

$ shishi --string-to-key --random \ krbtgt/latte.josefsson.org@latte.josefsson.org | \ tee /usr/local/etc/shishid.keys -----BEGIN SHISHI KEY----- Keytype: 18 (aes256-cts-hmac-sha1-96) Principal: krbtgt/latte.josefsson.org Realm: latte.josefsson.org oconxMTf59B5bvTylY+KE4mchA/gtmYI2Qok+48tnSM= -----END SHISHI KEY----- $

Create a key for a user from a specified password:

$ shishi --string-to-key=fnord \ simon@latte.josefsson.org | tee --append \ /usr/local/etc/shishid.keys -----BEGIN SHISHI KEY----- Keytype: 18 (aes256-cts-hmac-sha1-96) Principal: simon Realm: latte.josefsson.org c1rqwvYwuDFrABvqWVq9bWUsQWg/xbErsIUmLN+3lYM= -----END SHISHI KEY----- $

There is nothing special with a ticket granting key, you could have created it based on a password similar to the user key. However, please keep in mind that passwords typically have little entropy.

Finally, create a random key for a service:

$ shishi --string-to-key --random \ imap/latte.josefsson.org@latte.josefsson.org | \ tee --append /usr/local/etc/shishid.keys -----BEGIN SHISHI KEY----- Keytype: 18 (aes256-cts-hmac-sha1-96) Principal: imap/latte.josefsson.org Realm: latte.josefsson.org ts2v0QHWyW9FyXbWtCvLPqdEc60qPq5Yvat3p82rp5c= -----END SHISHI KEY----- $

You are now ready to start the KDC. Refer to the reference manual for available parameters (see Parameters for shishid).

$ shishid

Then you can use shishi as usual to acquire tickets (see User Manual). The following example demonstrate a AS-REQ for krbtgt/latte.josefsson.org followed by a TGS-REQ for imap/latte.josefsson.org.

$ shishi simon@latte.josefsson.org imap/latte.josefsson.org Enter password for `simon@latte.josefsson.org': simon@latte.josefsson.org: Acquired: Wed Aug 27 17:16:37 2003 Expires: Wed Aug 27 17:33:17 2003 Server: imap/latte.josefsson.org key aes256-cts-hmac-sha1-96 (18) Ticket key: aes256-cts-hmac-sha1-96 (18) protected by aes256-cts-hmac-sha1-96 (18) Ticket flags: FORWARDED PROXIABLE (12) $

4 Reference Manual

This chapter describes in high detail all parameters, configuration file verbs, etc.

• Configuration file: Meaning of tokens used in configuration file.
• Parameters for shishi: Command line parameters for 'shishi'.
• Parameters for shishid: Command line parameters for 'shishid'.

4.1 Configuration file

The valid configuration file tokens are described here. The user configuration file is typically located in ~/.shishi/shishi.conf (compare shishi --configuration-file) and the system configuration is typicall located in /usr/local/etc/shishi.conf. All tokens are valid in both files, and have the same meaning. However, as the system file is supposed to apply to all users on a system, it would not make sense to use some tokens in both files. For example, the default-principal is rarely useful in a system configuration file.

4.1.1 default-realm

Specify the default realm, by default the hostname of the host is used. E.g.,

     default-realm JOSEFSSON.ORG
     

4.1.2 default-principal

Specify the default principal, by default the login username is used. E.g.,

     default-principal jas
     

4.1.3 client-kdc-etypes

Specify which encryption types client asks server to respond in during AS/TGS exchanges. List valid encryption types, in preference order. Supported algorithms include aes256-cts-hmac-sha1-96, aes128-cts-hmac-sha1-96, des3-cbc-sha1-kd, des-cbc-md5, des-cbc-md4, des-cbc-crc and null. This option also indicates which encryption types are accepted by the client when receiving the response. Note that the preference order is not cryptographically protected, so a man in the middle can modify the order without being detected. Thus, only specify encryption types you trust completely here. The default only includes aes256-cts-hmac-sha1-96, as suggested by RFC1510bis. E.g.,

     client-kdc-etypes=aes256-cts-hmac-sha1-96 des3-cbc-sha1-kd des-cbc-md5
     

4.1.4 verbose, verbose-asn1, verbose-noice, verbose-crypto

Enable verbose library messages. E.g.,

     verbose
     verbose-noice
     

4.1.5 realm-kdc

Specify KDC addresses for realms. Value is REALM,KDCADDRESS[/PROTOCOL][,KDCADDRESS[/PROTOCOL]...].

KDCADDRESS is the hostname or IP address of KDC.

Optional PROTOCOL is udp for UDP, tcp for TCP, and TLS for TLS connections. By default UDP is tried first, and TCP used as a fallback if the KRB_ERR_RESPONSE_TOO_BIG error is received.

If not specified, Shishi tries to locate the KDC using SRV RRs, which is recommended. This option should normally only be used during experiments, or to access badly maintained realms.

     realm-kdc=JOSEFSSON.ORG,ristretto.josefsson.org
     

4.1.6 server-realm

Specify realm for servers. Value is REALM,SERVERREGEXP[,SERVERREGEXP...].

SERVERREGEXP is a regular expression matching servers in the realm. The first match is used. E.g.,

     server-realm=JOSEFSSON.ORG,.josefsson.org
     

Note: currently not used.

4.1.7 kdc-timeout, kdc-retries

How long shishi waits for a response from a KDC before continuing to next KDC for realm. The default is 5 seconds. E.g.,

     kdc-timeout=10
     

How many times shishi sends a request to a KDC before giving up. The default is 3 times. E.g.,

     kdc-retries=5
     

4.1.8 stringprocess

How username and passwords entered from the terminal, or taken from the command line, are processed.

"none": no processing is used.

"stringprep": convert from locale charset to UTF-8 and process using experimental RFC 1510 stringprep profile.

It can also be a string indicating a character set supported by iconv via libstringprep, in which case data is converted from locale charset into the indicated character set. E.g., UTF-8, ISO-8859-1, KOI-8, EBCDIC-IS-FRISS are supported on GNU systems. On some systems you can use "locale -m" to list available character sets. By default, the "none" setting is used which is consistent with RFC 1510 that is silent on the issue. In practice, however, converting to UTF-8 improves interoperability.

E.g.,

     stringprocess=UTF-8
     

4.1.9 ticket-life

Specify default ticket life time.

The string can be in almost any common format. It can contain month names, time zones, `am' and `pm', `yesterday', `ago', `next', etc. Refer to the "Date input formats" in the GNU CoreUtils package for entire story (see Date input formats). As an extra feature, if the resulting string you specify has expired within the last 24 hours, an extra day is added to it. This allows you to specify "17:00" to always mean the next 17:00, even if your system clock happens to be 17:30.

The default is 8 hours.

E.g.,

     #ticket-life=8 hours
     #ticket-life=1 day
     ticket-life=17:00
     

4.1.10 renew-life

Specify how long a renewable ticket should remain renewable.

See ticket-life for the syntax. The extra feature that handles negative values within the last 2 hours is not active here.

The default is 7 days.

E.g.,

     #renew-life=1 week
     #renew-life=friday 17:00
     renew-life=sunday
     

4.2 Parameters for shishi

If no command is given, Shishi try to make sure you have a ticket granting ticket for the default realm, and then display it.

Mandatory or optional arguments to long options are also mandatory or optional for any corresponding short options.

     Usage: shishi [OPTION...] [CLIENT [SERVER]] [OPTION...]
       or:  shishi [OPTION...] --list [CLIENT [SERVER]]
       or:  shishi [OPTION...] --destroy [CLIENT [SERVER]]
       or:  shishi [OPTION...] --string-to-key [CLIENT] [OPTION...]
       or:  shishi [OPTION...]
     Shishi -- A Kerberos 5 implementation
     
           --client-name=NAME     Client name. Default is login username.
       -d, --destroy              Destroy tickets in local cache, subject to
                                  --client-name and --server-name limiting.
       -e, --endtime=STRING       Specify when ticket validity should expire.  The
                                  time syntax may be relative (to the start time),
                                  such as "20 hours", or absolute, such as
                                  "2001-02-03 04:05:06 CET". The default is 8 hours
                                  after the start time.
       -E, --encryption-type=ETYPE,[ETYPE...]
                                  Encryption types to use.  ETYPE is either
                                  registered name or integer.
           --force-as             Force AS mode. Default is to use TGS iff a TGT is
                                  found.
           --force-tgs            Force TGS mode. Default is to use TGS iff a TGT is
                                  found.
           --forwardable          Get a forwardable ticket, i.e., one that can be
                                  used to get forwarded tickets.
           --forwarded            Get a forwarded ticket.
       -l, --list                 List tickets in local cache, subject to
                                  --server-name limiting.
           --proxiable            Get a proxiable ticket, i.e., one that can be used
                                  to get proxy tickets.
           --proxy                Get a proxy ticket.
           --realm=REALM          Realm of server. Default is DNS domain of local
                                  host. For AS, this also indicates realm of client.
           --renew-till=STRING    Specify renewable life of ticket.  Implies
                                  --renewable.  Accepts same time syntax as
                                  --endtime.  If --renewable is specified, the
                                  default is 1 week after the start time.
           --renewable            Get a renewable ticket.
       -R, --renew                Renew ticket.  Use --server-name to specify
                                  ticket, default is the most recent renewable
                                  ticket granting ticket for the default realm.
           --server=[FAMILY:]ADDRESS:SERVICE/TYPE
                                  Send all requests to HOST instead of using normal
                                  logic to locate KDC addresses (discouraged).
           --server-name=NAME     Server name. Default is "krbtgt/REALM" where REALM
                                  is server realm (see --realm).
       -s, --starttime=STRING     Specify when ticket should start to be valid.
                                  Accepts same time syntax as --endtime. The default
                                  is to become valid immediately.
           --ticket-granter=NAME  Service name in ticket to use for authenticating
                                  request. Only for TGS. Defaults to
                                  "krbtgt/REALM@REALM" where REALM is server realm
                                  (see --realm).
     
      Options for low-level cryptography (CRYPTO-OPTIONS):
           --client-name=NAME     Username. Default is login name.
           --key-version=INTEGER  Version number of key. Default is 0.
           --parameter=STRING     String-to-key parameter. This data is specific for
                                  each encryption algorithm and rarely needed.
           --random               Generate key from random data.
           --realm=REALM          Realm of principal. Defaults to DNS domain of
                                  local host.
           --salt=SALT            Salt to use for --string-to-key. Defaults to
                                  concatenation of realm and (unwrapped) client
                                  name.
           --string-to-key[=[PASSWORD]]
                                  Convert password into Kerberos key.  Note that
                                  --client-name, --realm, and --salt influence the
                                  generated key.
     
      Other options:
           --configuration-file=FILE   Read user configuration from file.  Default
                                  is ~/.shishi/config.
       -c, --ticket-file=FILE     Read tickets from FILE. Default is
                                  $HOME/.shishi/tickets.
       -o, --library-options=STRING   Parse STRING as a configuration file
                                  statement.
       -q, --quiet, --silent      Don't produce any output.
           --system-configuration-file=FILE
                                  Read system wide configuration from file.  Default
                                  is /usr/local/etc/shishi.conf.
           --ticket-write-file=FILE   Write tickets to FILE.  Default is to write
                                  them back to ticket file.
       -v, --verbose              Produce verbose output.  Use multiple times to
                                  increase amount of verbose output.
       CLIENT                     Set client name and realm from NAME.  The
                                  --client-name and --realm parameters can be used
                                  to override part of NAME.
       SERVER                     Set server name and realm from NAME.  The
                                  --server-name and --server-realm parameters can be
                                  used to override part of SERVER.
     
       -?, --help                 Give this help list
           --usage                Give a short usage message
       -V, --version              Print program version
     

4.3 Parameters for shishid

If no parameters are specified, shishid listens on the defaults interfaces and answers incoming requests using the keys in the default key file.

Mandatory or optional arguments to long options are also mandatory or optional for any corresponding short options.

       -c, --configuration-file=FILE   Read configuration from file.  Default is
                                  /usr/local/etc/shishi.conf.
       -k, --key-file=FILE        Read keys from file.  Default is
                                  /usr/local/etc/shishid.keys.
       -l, --listen=[FAMILY:]ADDRESS:SERVICE/TYPE,...
                                  What to listen on. Family is "IPv4" or "IPv6", if
                                  absent the family is decided by
                                  gethostbyname(ADDRESS). An address of "*"
                                  indicates all addresses on the local host. The
                                  default is "IPv4:*:kerberos/udp,
                                  IPv4:*:kerberos/tcp, IPv6:*:kerberos/udp,
                                  IPv6:*:kerberos/tcp".
       -q, -s, --quiet, --silent  Don't produce any output.
       -u, --setuid=NAME          After binding socket, set user identity.
       -v, --verbose              Produce verbose output.
       -?, --help                 Give this help list
           --usage                Give a short usage message
       -V, --version              Print program version
     

5 Programming Manual

This chapter describes all the publicly available functions in the library.

• Preparation: What you should do before using the library.
• Initialization Functions: Creating library handle, configuration file.
• Ticket Set Functions: High-level ticket management functions.
• AP-REQ and AP-REP Functions: Client/Server authentication functions.
• SAFE and PRIV Functions: Client/Server session data functions.
• Ticket Functions: Medium-level ticket manipulation functions.
• AS Functions: Medium-level initial authentication functions.
• TGS Functions: Medium-level authentication functions.
• Ticket (ASN.1) Functions: Low-level Ticket functions.
• AS/TGS Functions: Low-level KDC functions; AS and TGS.
• Authenticator Functions: Low-level authenticator functions.
• Cryptographic Functions: Low-level cryptographic functions.
• Utility Functions: Utilities for use in the global context.
• Error Handling: Error codes and such.
• Examples: Example code.
• Generic Security Service: If you want to use the GSS API instead.

5.1 Preparation

To use `Libshishi', you have to perform some changes to your sources and the build system. The necessary changes are small and explained in the following sections. At the end of this chapter, it is described how the library is initialized, and how the requirements of the library are verified.

A faster way to find out how to adapt your application for use with `Libshishi' may be to look at the examples at the end of this manual (see Examples).

• Header:
• Initialization:
• Version Check:
• Building the source:
• Autoconf tests:

5.1.1 Header

All interfaces (data types and functions) of the library are defined in the header file `shishi.h'. You must include this in all programs using the library, either directly or through some other header file, like this:

     #include <shishi.h>
     

The name space of `Libshishi' is shishi_* for function names, Shishi* for data types and SHISHI_* for other symbols. In addition the same name prefixes with one prepended underscore are reserved for internal use and should never be used by an application.

5.1.2 Initialization

`Libshishi' must be initialized before it can be used. The library is initialized by calling shishi_init (see Initialization Functions). The resources allocated by the initialization process can be released if the application no longer has a need to call `Libshishi' functions, this is done by calling shishi_done.

In order to take advantage of the internationalisation features in `Libshishi', such as translated error messages, the application must set the current locale using setlocale before initializing `Libshishi'.

5.1.3 Version Check

It is often desirable to check that the version of `Libshishi' used is indeed one which fits all requirements. Even with binary compatibility new features may have been introduced but due to problem with the dynamic linker an old version is actually used. So you may want to check that the version is okay right after program startup.

const char * shishi_check_version (const char * req_version)

Function

req_version: version string to compare with, or NULL Check that the the version of the library is at minimum the one given as a string in req_version. the actual version string of the library; NULL if the condition is not met. If NULL is passed to this function no check is done and only the version string is returned. It is a pretty good idea to run this function as soon as possible, because it may also intializes some subsystems. In a multithreaded environment if should be called before any more threads are created.

The normal way to use the function is to put something similar to the following early in your main:

       if (!shishi_check_version (SHISHI_VERSION))
         {
           printf ("shishi_check_version failed:\n"
                   "Header file incompatible with shared library.\n");
           exit(1);
         }
     

5.1.4 Building the source

If you want to compile a source file including the `shishi.h' header file, you must make sure that the compiler can find it in the directory hierarchy. This is accomplished by adding the path to the directory in which the header file is located to the compilers include file search path (via the -I option).

However, the path to the include file is determined at the time the source is configured. To solve this problem, `Libshishi' uses the external package pkg-config that knows the path to the include file and other configuration options. The options that need to be added to the compiler invocation at compile time are output by the --cflags option to pkg-config shishi. The following example shows how it can be used at the command line:

     gcc -c foo.c `pkg-config shishi --cflags`
     

Adding the output of pkg-config shishi --cflags to the compilers command line will ensure that the compiler can find the `Libshishi' header file.

A similar problem occurs when linking the program with the library. Again, the compiler has to find the library files. For this to work, the path to the library files has to be added to the library search path (via the -L option). For this, the option --libs to pkg-config shishi can be used. For convenience, this option also outputs all other options that are required to link the program with the `Libshishi' libararies (in particular, the -lshishi option). The example shows how to link foo.o with the `Libshishi' library to a program foo.

     gcc -o foo foo.o `pkg-config shishi --libs`
     

Of course you can also combine both examples to a single command by specifying both options to pkg-config:

     gcc -o foo foo.c `pkg-config shishi --cflags --libs`
     

5.1.5 Autoconf tests

If you work on a project that uses Autoconf (see GNU Autoconf) to help find installed libraries, the suggestions in the previous section are not the entire story. There are a few methods to detect and incorporate Shishi into your Autoconf based package. The preferred approach, is to use Libtool in your project, and use the normal Autoconf header file and library tests.

5.1.5.1 Autoconf test via pkg-config

If your audience is a typical GNU/Linux desktop, you can often assume they have the pkg-config tool installed, in which you can use its Autoconf M4 macro to find and set up your package for use with Shishi. The following illustrate this scenario.

     AC_ARG_ENABLE(kerberos_v5,
     	AC_HELP_STRING([--disable-kerberos_v5],
                            [don't use the KERBEROS_V5 mechanism]),
     	kerberos_v5=$enableval)
     if test "$kerberos_v5" != "no" ; then
     	PKG_CHECK_MODULES(SHISHI, shishi >= 0.0.0,
     			[kerberos_v5=yes],
                             [kerberos_v5=no])
     	if test "$kerberos_v5" != "yes" ; then
     		kerberos_v5=no
     		AC_MSG_WARN([shishi not found, disabling Kerberos 5])
     	else
     		kerberos_v5=yes
     		AC_DEFINE(USE_KERBEROS_V5, 1,
                               [Define to 1 if you want Kerberos 5.])
     	fi
     fi
     AC_MSG_CHECKING([if Kerberos 5 should be used])
     AC_MSG_RESULT($kerberos_v5)
     

5.1.5.2 Standalone Autoconf test using Libtool

If your package uses Libtool(see GNU Libtool), you can use the normal Autoconf tests to find the Shishi library and rely on the Libtool dependency tracking to include the proper dependency libraries (e.g., Libidn). The following illustrate this scenario.

     AC_CHECK_HEADER(shishi.h,
     	AC_CHECK_LIB(shishi, shishi_check_version,
     		[kerberos5=yes AC_SUBST(SHISHI_LIBS, -lshishi)],
     		kerberos5=no),
     	kerberos5=no)
     AC_ARG_ENABLE(kerberos5,
     	AC_HELP_STRING([--disable-kerberos5],
                            [disable Kerberos 5 unconditionally]),
     	kerberos5=$enableval)
     if test "$kerberos5" != "no" ; then
     	AC_DEFINE(USE_KERBEROS_V5, 1,
     		  [Define to 1 if you want Kerberos 5.])
     else
     	AC_MSG_WARN([Shishi not found, disabling Kerberos 5])
     fi
     AC_MSG_CHECKING([if Kerberos 5 should be used])
     AC_MSG_RESULT($kerberos5)
     

5.1.5.3 Standalone Autoconf test

If your package does not use Libtool, as well as detecting the Shishi library as in the previous case, you must also detect whatever dependencies Shishi requires to work (e.g., libidn). Since the dependencies are in a state of flux, we do not provide an example and we do not recommend this approach, unless you are experienced developer.

5.2 Initialization Functions

Shishi * shishi ( void)

Function

Initializes the Shishi library, and set up, using shishi_set_outputtype(), the library so that future warnings and informational messages are printed to stderr. If this function fails, it may print diagnostic errors to stderr. Returns Shishi library handle, or NULL on error.

Shishi * shishi_server ( void)

Function

Initializes the Shishi library, and set up, using shishi_set_outputtype(), the library so that future warnings and informational messages are printed to the syslog. If this function fails, it may print diagnostic errors to the syslog. Returns Shishi library handle, or NULL on error.

void shishi_done (Shishi * handle)

Function

handle: shishi handle as allocated by shishi_init(). Deallocates the shishi library handle. The handle must not be used in any calls to shishi functions after this. If there is a default tkts, it is written to the default tkts file (call shishi_tkts_default_file_set() to change the default tkts file). If you do not wish to write the default tkts file, close the default tkts with shishi_tkts_done(handle, NULL) before calling this function.

int shishi_init (Shishi ** handle)

Function

handle: pointer to handle to be created. Create a Shishi library handle, using shishi(), and read the system configuration file, user configuration file and user tickets from their default locations. The paths to the system configuration file is decided at compile time, and is $sysconfdir/shishi.conf. The user configuration file is $HOME/.shishi/config, and the user ticket file is $HOME/.shishi/ticket. The handle is allocated regardless of return values, except for SHISHI_HANDLE_ERROR which indicates a problem allocating the handle. (The other error conditions comes from reading the files.) Returns SHISHI_OK iff successful.

int shishi_init_with_paths (Shishi ** handle, const char * tktsfile, const char * systemcfgfile, const char * usercfgfile)

Function

handle: pointer to handle to be created. tktsfile: Filename of ticket file, or NULL. systemcfgfile: Filename of system configuration, or NULL. usercfgfile: Filename of user configuration, or NULL. Create a Shishi library handle, using shishi(), and read the system configuration file, user configuration file, and user tickets from the specified locations. If any of usercfgfile or systemcfgfile is NULL, the file is read from its default location, which for the system configuration file is decided at compile time, and is $sysconfdir/shishi.conf, and for the user configuration file is $HOME/.shishi/config. If the ticket file is NULL, a ticket file is not read at all. The handle is allocated regardless of return values, except for SHISHI_HANDLE_ERROR which indicates a problem allocating the handle. (The other error conditions comes from reading the files.) Returns SHISHI_OK iff successful.

int shishi_init_server (Shishi ** handle)

Function

handle: pointer to handle to be created. Create a Shishi library handle, using shishi_server(), and read the system configuration file. The paths to the system configuration file is decided at compile time, and is $sysconfdir/shishi.conf. The handle is allocated regardless of return values, except for SHISHI_HANDLE_ERROR which indicates a problem allocating the handle. (The other error conditions comes from reading the file.) Returns SHISHI_OK iff successful.

int shishi_init_server_with_paths (Shishi ** handle, const char * systemcfgfile)

Function

handle: pointer to handle to be created. systemcfgfile: Filename of system configuration, or NULL. Create a Shishi library handle, using shishi_server(), and read the system configuration file from specified location. The paths to the system configuration file is decided at compile time, and is $sysconfdir/shishi.conf. The handle is allocated regardless of return values, except for SHISHI_HANDLE_ERROR which indicates a problem allocating the handle. (The other error conditions comes from reading the file.) Returns SHISHI_OK iff successful.

int shishi_cfg (Shishi * handle, char * option)

Function

handle: Shishi library handle create by shishi_init(). option: string with shishi library option. Configure shishi library with given option. Returns SHISHI_OK if option was valid.

int shishi_cfg_from_file (Shishi * handle, const char * cfg)

Function

handle: Shishi library handle create by shishi_init(). cfg: filename to read configuration from. Configure shishi library using configuration file. Returns SHISHI_OK iff succesful.

int shishi_cfg_print (Shishi * handle, FILE * fh)

Function

handle: Shishi library handle create by shishi_init(). fh: file descriptor opened for writing. Print library configuration status, mostly for debugging purposes. Returns SHISHI_OK.

const char * shishi_cfg_default_systemfile (Shishi * handle)

Function

handle: Shishi library handle create by shishi_init(). Return system configuration filename.

const char * shishi_cfg_default_userdirectory (Shishi * handle)

Function

handle: Shishi library handle create by shishi_init(). Return directory with configuration files etc.

const char * shishi_cfg_default_userfile (Shishi * handle)

Function

handle: Shishi library handle create by shishi_init(). Return user configuration filename.

int shishi_cfg_clientkdcetype (Shishi * handle, int32_t ** etypes)

Function

handle: Shishi library handle create by shishi_init(). etypes: output array with encryption types. Set the etypes variable to the array of preferred client etypes. Return the number of encryption types in the array, 0 means none.

int shishi_cfg_clientkdcetype_set (Shishi * handle, char * value)

Function

handle: Shishi library handle create by shishi_init(). value: string with encryption types. Set the "client-kdc-etypes" configuration option from given string. The string contains encryption types (integer or names) separated by comma or whitespace, e.g. "aes256-cts-hmac-sha1-96 des3-cbc-sha1-kd des-cbc-md5". Return SHISHI_OK iff successful.

5.3 Ticket Set Functions

A "ticket set" is, as the name implies, a collection of tickets. Functions are provided to read tickets from file into a ticket set, to query number of tickets in the set, to extract a given ticket from the set, to search the ticket set for tickets matching certain criterium, to write the ticket set to a file, etc. High level functions for performing a initial authentication (see AS Functions) or subsequent authentication (see TGS Functions) and storing the new ticket in the ticket set are also provided.

To manipulate each individual ticket, See Ticket Functions. For low-level ASN.1 manipulation see See Ticket (ASN.1) Functions.

char * shishi_tkts_default_file_guess ( void)

Function

Guesses the default ticket filename; it is $HOME/.shishi/tickets. Returns default tkts filename as a string that has to be deallocated with free() by the caller.

const char * shishi_tkts_default_file (Shishi * handle)

Function

handle: Shishi library handle create by shishi_init(). Returns the default ticket set filename used in the library. (Not a copy of it, so don't modify or deallocate it.)

void shishi_tkts_default_file_set (Shishi * handle, const char * tktsfile)

Function

handle: Shishi library handle create by shishi_init(). tktsfile: string with new default tkts file name, or NULL to reset to default. Set the default ticket set filename used in the library. The string is copied into the library, so you can dispose of the variable immediately after calling this function.

Shishi_tkts * shishi_tkts_default (Shishi * handle)

Function

handle: Shishi library handle create by shishi_init(). Return the handle global ticket set.

int shishi_tkts (Shishi * handle, Shishi_tkts ** tkts)

Function

handle: shishi handle as allocated by shishi_init(). tkts: output pointer to newly allocated tkts handle. Returns SHISHI_OK iff successful.

void shishi_tkts_done (Shishi_tkts ** tkts)

Function

tkts: ticket set handle as allocated by shishi_tkts(). Deallocates all resources associated with ticket set. The ticket set handle must not be used in calls to other shishi_tkts_*() functions after this.

int shishi_tkts_size (Shishi_tkts * tkts)

Function

tkts: ticket set handle as allocated by shishi_tkts(). Returns number of tickets stored in ticket set.

Shishi_tkt * shishi_tkts_nth (Shishi_tkts * tkts, int ticketno)

Function

tkts: ticket set handle as allocated by shishi_tkts(). ticketno: integer indicating requested ticket in ticket set. Returns a ticket handle to the ticketno:th ticket in the ticket set, or NULL if ticket set is invalid or ticketno is out of bounds. The first ticket is ticketno 0, the second ticketno 1, and so on.

int shishi_tkts_remove (Shishi_tkts * tkts, int ticketno)

Function

tkts: ticket set handle as allocated by shishi_tkts(). ticketno: ticket number of ticket in the set to remove. The first ticket is ticket number 0. Returns SHISHI_OK if succesful or if ticketno larger than size of ticket set.

int shishi_tkts_add (Shishi_tkts * tkts, Shishi_tkt * tkt)

Function

tkts: ticket set handle as allocated by shishi_tkts(). tkt: ticket to be added to ticket set. Returns SHISHI_OK iff succesful.

int shishi_tkts_new (Shishi_tkts * tkts, Shishi_asn1 ticket, Shishi_asn1 enckdcreppart, Shishi_asn1 kdcrep)

Function

tkts: ticket set handle as allocated by shishi_tkts(). ticket: input ticket variable. enckdcreppart: input ticket detail variable. kdcrep: input KDC-REP variable. Allocate a new ticket and add it to the ticket set. Returns SHISHI_OK iff succesful.

int shishi_tkts_read (Shishi_tkts * tkts, FILE * fh)

Function

tkts: ticket set handle as allocated by shishi_tkts(). fh: file descriptor to read from. Read tickets from file descriptor and add them to the ticket set. Returns SHISHI_OK iff succesful.

int shishi_tkts_from_file (Shishi_tkts * tkts, const char * filename)

Function

tkts: ticket set handle as allocated by shishi_tkts(). filename: filename to read tickets from. Read tickets from file and add them to the ticket set. Returns SHISHI_OK iff succesful.

int shishi_tkts_write (Shishi_tkts * tkts, FILE * fh)

Function

tkts: ticket set handle as allocated by shishi_tkts(). fh: file descriptor to write tickets to. Write tickets in set to file descriptor. Returns SHISHI_OK iff succesful.

int shishi_tkts_expire (Shishi_tkts * tkts)

Function

tkts: ticket set handle as allocated by shishi_tkts(). Remove expired tickets from ticket set. Returns SHISHI_OK iff succesful.

int shishi_tkts_to_file (Shishi_tkts * tkts, const char * filename)

Function

tkts: ticket set handle as allocated by shishi_tkts(). filename: filename to write tickets to. Write tickets in set to file. Returns SHISHI_OK iff succesful.

int shishi_tkts_print_for_service (Shishi_tkts * tkts, FILE * fh, const char * service)

Function

tkts: ticket set handle as allocated by shishi_tkts(). fh: file descriptor to print to. service: service to limit tickets printed to, or NULL. Print description of tickets for specified service to file descriptor. If service is NULL, all tickets are printed. Returns SHISHI_OK iff succesful.

int shishi_tkts_print (Shishi_tkts * tkts, FILE * fh)

Function

tkts: ticket set handle as allocated by shishi_tkts(). fh: file descriptor to print to. Print description of all tickets to file descriptor. Returns SHISHI_OK iff succesful.

int shishi_tkt_match_p (Shishi_tkt * tkt, Shishi_tkts_hint * hint)

Function

tkt: ticket to test hints on. hint: structure with characteristics of ticket to be found. Returns 0 iff ticket fails to match given criteria.

Shishi_tkt * shishi_tkts_find (Shishi_tkts * tkts, Shishi_tkts_hint * hint)

Function

tkts: ticket set handle as allocated by shishi_tkts(). hint: structure with characteristics of ticket to be found. Search the ticketset sequentially (from ticket number 0 through all tickets in the set) for a ticket that fits the given characteristics. If a ticket is found, the hint->startpos field is updated to point to the next ticket in the set, so this function can be called repeatedly with the same hint argument in order to find all tickets matching a certain criterium. Note that if tickets are added to, or removed from, the ticketset during a query with the same hint argument, the hint->startpos field must be updated appropriately. Shishi_tkts_hint hint; Shishi_tkt tkt; ... memset(hint, 0, sizeof(hint)); hint.server = "imap/mail.example.org"; tkt = shishi_tkts_find (shishi_tkts_default(handle), hint); if (!tkt) printf("No ticket found...\n"); else ...do something with ticket Returns a ticket if found, or NULL if no further matching tickets could be found.

Shishi_tkt * shishi_tkts_find_for_clientserver (Shishi_tkts * tkts, const char * client, const char * server)

Function

tkts: ticket set handle as allocated by shishi_tkts(). client: client name to find ticket for. server: server name to find ticket for. Short-hand function for searching the ticket set for a ticket for the given client and server. See shishi_tkts_find(). Returns a ticket if found, or NULL.

Shishi_tkt * shishi_tkts_find_for_server (Shishi_tkts * tkts, const char * server)

Function

tkts: ticket set handle as allocated by shishi_tkts(). server: server name to find ticket for. Short-hand function for searching the ticket set for a ticket for the given server using the default client principal. See shishi_tkts_find_for_clientserver() and shishi_tkts_find(). Returns a ticket if found, or NULL.

Shishi_tkt * shishi_tkts_get_tgt (Shishi_tkts * tkts, Shishi_tkts_hint * hint)

Function

tkts: ticket set handle as allocated by shishi_tkts(). hint: structure with characteristics of ticket to begot. Get a ticket granting ticket (TGT) suitable for acquiring ticket matching the hint. I.e., get a TGT for the server realm in the hint structure (hint->serverrealm), or the default realm if the serverrealm field is NULL. Can result in AS exchange. Currently this function do not implement cross realm logic. This function is used by shishi_tkts_get(), which is probably what you really want to use unless you have special needs. Returns a ticket granting ticket if successful, or NULL if this function is unable to acquire on.

Shishi_tkt * shishi_tkts_get_tgs (Shishi_tkts * tkts, Shishi_tkts_hint * hint, Shishi_tkt * tgt)

Function

tkts: ticket set handle as allocated by shishi_tkts(). hint: structure with characteristics of ticket to begot. tgt: ticket granting ticket to use. Get a ticket via TGS exchange using specified ticket granting ticket. This function is used by shishi_tkts_get(), which is probably what you really want to use unless you have special needs. Returns a ticket if successful, or NULL if this function is unable to acquire on.

Shishi_tkt * shishi_tkts_get (Shishi_tkts * tkts, Shishi_tkts_hint * hint)

Function

tkts: ticket set handle as allocated by shishi_tkts(). hint: structure with characteristics of ticket to begot. Get a ticket matching given characteristics. This function first looks in the ticket set for the ticket, then tries to find a suitable TGT, possibly via an AS exchange, using shishi_tkts_get_tgt(), and then use that TGT in a TGS exchange to get the ticket. Currently this function do not implement cross realm logic. Returns a ticket if found, or NULL if this function is unable to get the ticket.

Shishi_tkt * shishi_tkts_get_for_clientserver (Shishi_tkts * tkts, const char * client, const char * server)

Function

tkts: ticket set handle as allocated by shishi_tkts(). client: client name to get ticket for. server: server name to get ticket for. Short-hand function for getting a ticket for the given client and server. See shishi_tkts_get(). Returns a ticket if found, or NULL.

Shishi_tkt * shishi_tkts_get_for_server (Shishi_tkts * tkts, const char * server)

Function

tkts: ticket set handle as allocated by shishi_tkts(). server: server name to get ticket for. Short-hand function for getting a ticket for the given server and the default principal client. See shishi_tkts_get(). Returns a ticket if found, or NULL.

5.4 AP-REQ and AP-REP Functions

The "AP-REQ" and "AP-REP" are ASN.1 structures used by application client and servers to prove to each other who they are. The structures contain auxilliary information, together with an authenticator (see Authenticator Functions) which is the real cryptographic proof. The following illustrates the AP-REQ and AP-REP ASN.1 structures.

AP-REQ		::= [APPLICATION 14] SEQUENCE {
	pvno		[0] INTEGER (5),
	msg-type	[1] INTEGER (14),
	ap-options	[2] APOptions,
	ticket		[3] Ticket,
	authenticator	[4] EncryptedData {Authenticator,
				{ keyuse-pa-TGSReq-authenticator
				  | keyuse-APReq-authenticator }}
}

AP-REP		::= [APPLICATION 15] SEQUENCE {
	pvno		[0] INTEGER (5),
	msg-type	[1] INTEGER (15),
	enc-part	[2] EncryptedData {EncAPRepPart,
				{ keyuse-EncAPRepPart }}
}

EncAPRepPart	::= [APPLICATION 27] SEQUENCE {
	ctime		[0] KerberosTime,
	cusec		[1] Microseconds,
	subkey		[2] EncryptionKey OPTIONAL,
	seq-number	[3] UInt32 OPTIONAL
}

int shishi_ap (Shishi * handle, Shishi_ap ** ap)

Function

handle: shishi handle as allocated by shishi_init(). ap: pointer to new structure that holds information about AP exchange Create a new AP exchange. Returns SHISHI_OK iff successful.

int shishi_ap_nosubkey (Shishi * handle, Shishi_ap ** ap)

Function

handle: shishi handle as allocated by shishi_init(). ap: pointer to new structure that holds information about AP exchange Create a new AP exchange without subkey in authenticator. Returns SHISHI_OK iff successful.

void shishi_ap_done (Shishi_ap * ap)

Function

ap: structure that holds information about AP exchange Deallocate resources associated with AP exchange. This should be called by the application when it no longer need to utilize the AP exchange handle.

int shishi_ap_set_tktoptions (Shishi_ap * ap, Shishi_tkt * tkt, int options)

Function

ap: structure that holds information about AP exchange tkt: ticket to set in AP. options: AP-REQ options to set in AP. Set the ticket (see shishi_ap_tkt_set()) and set the AP-REQ apoptions (see shishi_apreq_options_set()). Returns SHISHI_OK iff successful.

int shishi_ap_set_tktoptionsdata (Shishi_ap * ap, Shishi_tkt * tkt, int options, const char * data, size_t len)

Function

ap: structure that holds information about AP exchange tkt: ticket to set in AP. options: AP-REQ options to set in AP. data: input array with data to checksum in Authenticator. len: length of input array with data to checksum in Authenticator. Set the ticket (see shishi_ap_tkt_set()) and set the AP-REQ apoptions (see shishi_apreq_options_set()) and set the Authenticator checksum data. Returns SHISHI_OK iff successful.

int shishi_ap_set_tktoptionsasn1usage (Shishi_ap * ap, Shishi_tkt * tkt, int options, Shishi_asn1 node, char * field, int authenticatorcksumkeyusage, int authenticatorkeyusage)

Function

ap: structure that holds information about AP exchange tkt: ticket to set in AP. options: AP-REQ options to set in AP. node: input ASN.1 structure to store as authenticator checksum data. field: field in ASN.1 structure to use. authenticatorcksumkeyusage: key usage for checksum in authenticator. authenticatorkeyusage: key usage for authenticator. Set ticket, options and authenticator checksum data using shishi_ap_set_tktoptionsdata(). The authenticator checksum data is the DER encoding of the ASN.1 field provided. Returns SHISHI_OK iff successful.

int shishi_ap_tktoptions (Shishi * handle, Shishi_ap ** ap, Shishi_tkt * tkt, int options)

Function

handle: shishi handle as allocated by shishi_init(). ap: pointer to new structure that holds information about AP exchange tkt: ticket to set in newly created AP. options: AP-REQ options to set in newly created AP. Create a new AP exchange using shishi_ap(), and set the ticket and AP-REQ apoptions using shishi_ap_set_tktoption(). Returns SHISHI_OK iff successful.

int shishi_ap_tktoptionsdata (Shishi * handle, Shishi_ap ** ap, Shishi_tkt * tkt, int options, const char * data, size_t len)

Function

handle: shishi handle as allocated by shishi_init(). ap: pointer to new structure that holds information about AP exchange tkt: ticket to set in newly created AP. options: AP-REQ options to set in newly created AP. data: input array with data to checksum in Authenticator. len: length of input array with data to checksum in Authenticator. Create a new AP exchange using shishi_ap(), and set the ticket, AP-REQ apoptions and the Authenticator checksum data using shishi_ap_set_tktoptionsdata(). Returns SHISHI_OK iff successful.

int shishi_ap_tktoptionsasn1usage (Shishi * handle, Shishi_ap ** ap, Shishi_tkt * tkt, int options, Shishi_asn1 node, char * field, int authenticatorcksumkeyusage, int authenticatorkeyusage)

Function

handle: shishi handle as allocated by shishi_init(). ap: pointer to new structure that holds information about AP exchange tkt: ticket to set in newly created AP. options: AP-REQ options to set in newly created AP. node: input ASN.1 structure to store as authenticator checksum data. field: field in ASN.1 structure to use. authenticatorcksumkeyusage: key usage for checksum in authenticator. authenticatorkeyusage: key usage for authenticator. Create a new AP exchange using shishi_ap(), and set ticket, options and authenticator checksum data from the DER encoding of the ASN.1 field using shishi_ap_set_tktoptionsasn1usage(). Returns SHISHI_OK iff successful.

Shishi_tkt * shishi_ap_tkt (Shishi_ap * ap)

Function

ap: structure that holds information about AP exchange Returns the ticket from the AP exchange, or NULL if not yet set or an error occured.

void shishi_ap_tkt_set (Shishi_ap * ap, Shishi_tkt * tkt)

Function

ap: structure that holds information about AP exchange tkt: ticket to store in AP. Set the Ticket in the AP exchange.

int shishi_ap_authenticator_cksumdata (Shishi_ap * ap, char * out, size_t * len)

Function

ap: structure that holds information about AP exchange out: output array that holds authenticator checksum data. len: on input, maximum length of output array that holds authenticator checksum data, on output actual length of output array that holds authenticator checksum data. Returns SHISHI_OK if successful, or SHISHI_TOO_SMALL_BUFFER if buffer provided was too small.

void shishi_ap_authenticator_cksumdata_set (Shishi_ap * ap, const char * authenticatorcksumdata, size_t authenticatorcksumdatalen)

Function

ap: structure that holds information about AP exchange authenticatorcksumdata: input array with authenticator checksum data to use in AP. authenticatorcksumdatalen: length of input array with authenticator checksum data to use in AP. Set the Authenticator Checksum Data in the AP exchange.

int shishi_ap_authenticator_cksumtype (Shishi_ap * ap)

Function

ap: structure that holds information about AP exchange Get the Authenticator Checksum Type in the AP exchange. Return the authenticator checksum type.

void shishi_ap_authenticator_cksumtype_set (Shishi_ap * ap, int cksumtype)

Function

ap: structure that holds information about AP exchange cksumtype: authenticator checksum type to set in AP. Set the Authenticator Checksum Type in the AP exchange.

Shishi_asn1 shishi_ap_authenticator (Shishi_ap * ap)

Function

ap: structure that holds information about AP exchange Returns the Authenticator from the AP exchange, or NULL if not yet set or an error occured.

void shishi_ap_authenticator_set (Shishi_ap * ap, Shishi_asn1 authenticator)

Function

ap: structure that holds information about AP exchange authenticator: authenticator to store in AP. Set the Authenticator in the AP exchange.

Shishi_asn1 shishi_ap_req (Shishi_ap * ap)

Function

ap: structure that holds information about AP exchange Returns the AP-REQ from the AP exchange, or NULL if not yet set or an error occured.

void shishi_ap_req_set (Shishi_ap * ap, Shishi_asn1 apreq)

Function

ap: structure that holds information about AP exchange apreq: apreq to store in AP. Set the AP-REQ in the AP exchange.

int shishi_ap_req_der (Shishi_ap * ap, char ** out, size_t * outlen)

Function

ap: structure that holds information about AP exchange out: pointer to output array with der encoding of AP-REQ. outlen: pointer to length of output array with der encoding of AP-REQ. Build AP-REQ using shishi_ap_req_build() and DER encode it. out is allocated by this function, and it is the responsibility of caller to deallocate it. Returns SHISHI_OK iff successful.

int shishi_ap_req_der_set (Shishi_ap * ap, char * der, size_t derlen)

Function

ap: structure that holds information about AP exchange der: input array with DER encoded AP-REQ. derlen: length of input array with DER encoded AP-REQ. DER decode AP-REQ and set it AP exchange. If decoding fails, the AP-REQ in the AP exchange is lost. Returns SHISHI_OK.

int shishi_ap_req_build (Shishi_ap * ap)

Function

ap: structure that holds information about AP exchange Checksum data in authenticator and add ticket and authenticator to AP-REQ. Returns SHISHI_OK iff successful.

int shishi_ap_req_process_keyusage (Shishi_ap * ap, Shishi_key * key, int32_t keyusage)

Function

ap: structure that holds information about AP exchange key: cryptographic key used to decrypt ticket in AP-REQ. keyusage: key usage to use during decryption, for normal AP-REQ's this is normally SHISHI_KEYUSAGE_APREQ_AUTHENTICATOR, for AP-REQ's part of TGS-REQ's, this is normally SHISHI_KEYUSAGE_TGSREQ_APREQ_AUTHENTICATOR. Decrypt ticket in AP-REQ using supplied key and decrypt Authenticator in AP-REQ using key in decrypted ticket, and on success set the Ticket and Authenticator fields in the AP exchange. Returns SHISHI_OK iff successful.

int shishi_ap_req_process (Shishi_ap * ap, Shishi_key * key)

Function

ap: structure that holds information about AP exchange key: cryptographic key used to decrypt ticket in AP-REQ. Decrypt ticket in AP-REQ using supplied key and decrypt Authenticator in AP-REQ using key in decrypted ticket, and on success set the Ticket and Authenticator fields in the AP exchange. Returns SHISHI_OK iff successful.

int shishi_ap_req_asn1 (Shishi_ap * ap, Shishi_asn1 * apreq)

Function

ap: structure that holds information about AP exchange apreq: output AP-REQ variable. Build AP-REQ using shishi_ap_req_build() and return it. Returns SHISHI_OK iff successful.

Shishi_key * shishi_ap_key (Shishi_ap * ap)

Function

ap: structure that holds information about AP exchange Extract the application key from AP. If subkeys are used, it is taken from the Authenticator, otherwise the session key is used. Return application key from AP.

Shishi_asn1 shishi_ap_rep (Shishi_ap * ap)

Function

ap: structure that holds information about AP exchange Returns the AP-REP from the AP exchange, or NULL if not yet set or an error occured.

void shishi_ap_rep_set (Shishi_ap * ap, Shishi_asn1 aprep)

Function

ap: structure that holds information about AP exchange aprep: aprep to store in AP. Set the AP-REP in the AP exchange.

int shishi_ap_rep_der (Shishi_ap * ap, char ** out, size_t * outlen)

Function

ap: structure that holds information about AP exchange out: output array with newly allocated DER encoding of AP-REP. outlen: length of output array with DER encoding of AP-REP. Build AP-REP using shishi_ap_rep_build() and DER encode it. out is allocated by this function, and it is the responsibility of caller to deallocate it. Returns SHISHI_OK iff successful.

int shishi_ap_rep_der_set (Shishi_ap * ap, char * der, size_t derlen)

Function

ap: structure that holds information about AP exchange der: input array with DER encoded AP-REP. derlen: length of input array with DER encoded AP-REP. DER decode AP-REP and set it AP exchange. If decoding fails, the AP-REP in the AP exchange remains. Returns SHISHI_OK.

int shishi_ap_rep_build (Shishi_ap * ap)

Function

ap: structure that holds information about AP exchange Checksum data in authenticator and add ticket and authenticator to AP-REP. Returns SHISHI_OK iff successful.

int shishi_ap_rep_asn1 (Shishi_ap * ap, Shishi_asn1 * aprep)

Function

ap: structure that holds information about AP exchange aprep: output AP-REP variable. Build AP-REP using shishi_ap_rep_build() and return it. Returns SHISHI_OK iff successful.

int shishi_ap_rep_verify (Shishi_ap * ap)

Function

ap: structure that holds information about AP exchange Verify AP-REP compared to Authenticator. Returns SHISHI_OK, SHISHI_APREP_VERIFY_FAILED or an error.

int shishi_ap_rep_verify_der (Shishi_ap * ap, char * der, size_t derlen)

Function

ap: structure that holds information about AP exchange der: input array with DER encoded AP-REP. derlen: length of input array with DER encoded AP-REP. DER decode AP-REP and set it in AP exchange using shishi_ap_rep_der_set() and verify it using shishi_ap_rep_verify(). Returns SHISHI_OK, SHISHI_APREP_VERIFY_FAILED or an error.

int shishi_ap_rep_verify_asn1 (Shishi_ap * ap, Shishi_asn1 aprep)

Function

ap: structure that holds information about AP exchange aprep: input AP-REP. Set the AP-REP in the AP exchange using shishi_ap_rep_set() and verify it using shishi_ap_rep_verify(). Returns SHISHI_OK, SHISHI_APREP_VERIFY_FAILED or an error.

Shishi_asn1 shishi_ap_encapreppart (Shishi_ap * ap)

Function

ap: structure that holds information about AP exchange Returns the EncAPREPPart from the AP exchange, or NULL if not yet set or an error occured.

void shishi_ap_encapreppart_set (Shishi_ap * ap, Shishi_asn1 encapreppart)

Function

ap: structure that holds information about AP exchange encapreppart: EncAPRepPart to store in AP. Set the EncAPRepPart in the AP exchange.

const char * shishi_ap_option2string (Shishi_apoptions option)

Function

option: enumerated AP-Option type, see Shishi_apoptions. Convert AP-Option type to AP-Option name string. Note that option must be just one of the AP-Option types, it cannot be an binary ORed indicating several AP-Options. Returns static string with name of AP-Option that must not be deallocated, or "unknown" if AP-Option was not understood.

Shishi_apoptions shishi_ap_string2option (const char * str)

Function

str: zero terminated character array with name of AP-Option, e.g. "use-session-key". Convert AP-Option name to AP-Option type. Returns enumerated type member corresponding to AP-Option, or 0 if string was not understood.

Shishi_asn1 shishi_apreq (Shishi * handle)

Function

handle: shishi handle as allocated by shishi_init(). This function creates a new AP-REQ, populated with some default values. Returns the AP-REQ or NULL on failure.

int shishi_apreq_print (Shishi * handle, FILE * fh, Shishi_asn1 apreq)

Function

handle: shishi handle as allocated by shishi_init(). fh: file handle open for writing. apreq: AP-REQ to print. Print ASCII armored DER encoding of AP-REQ to file. Returns SHISHI_OK iff successful.

int shishi_apreq_save (Shishi * handle, FILE * fh, Shishi_asn1 apreq)

Function

handle: shishi handle as allocated by shishi_init(). fh: file handle open for writing. apreq: AP-REQ to save. Save DER encoding of AP-REQ to file. Returns SHISHI_OK iff successful.

int shishi_apreq_to_file (Shishi * handle, Shishi_asn1 apreq, int filetype, char * filename)

Function

handle: shishi handle as allocated by shishi_init(). apreq: AP-REQ to save. filetype: input variable specifying type of file to be written, see Shishi_filetype. filename: input variable with filename to write to. Write AP-REQ to file in specified TYPE. The file will be truncated if it exists. Returns SHISHI_OK iff successful.

int shishi_apreq_parse (Shishi * handle, FILE * fh, Shishi_asn1 * apreq)

Function

handle: shishi handle as allocated by shishi_init(). fh: file handle open for reading. apreq: output variable with newly allocated AP-REQ. Read ASCII armored DER encoded AP-REQ from file and populate given variable. Returns SHISHI_OK iff successful.

int shishi_apreq_read (Shishi * handle, FILE * fh, Shishi_asn1 * apreq)

Function

handle: shishi handle as allocated by shishi_init(). fh: file handle open for reading. apreq: output variable with newly allocated AP-REQ. Read DER encoded AP-REQ from file and populate given variable. Returns SHISHI_OK iff successful.

int shishi_apreq_from_file (Shishi * handle, Shishi_asn1 * apreq, int filetype, char * filename)

Function

handle: shishi handle as allocated by shishi_init(). apreq: output variable with newly allocated AP-REQ. filetype: input variable specifying type of file to be read, see Shishi_filetype. filename: input variable with filename to read from. Read AP-REQ from file in specified TYPE. Returns SHISHI_OK iff successful.

int shishi_apreq_set_authenticator (Shishi * handle, Shishi_asn1 apreq, int32_t etype, const char * buf, size_t buflen)

Function

handle: shishi handle as allocated by shishi_init(). apreq: AP-REQ to add authenticator field to. etype: encryption type used to encrypt authenticator. buf: input array with encrypted authenticator. buflen: size of input array with encrypted authenticator. Set the encrypted authenticator field in the AP-REP. The encrypted data is usually created by calling shishi_encrypt() on the DER encoded authenticator. To save time, you may want to use shishi_apreq_add_authenticator() instead, which calculates the encrypted data and calls this function in one step.

int shishi_apreq_add_authenticator (Shishi * handle, Shishi_asn1 apreq, Shishi_key * key, int keyusage, Shishi_asn1 authenticator)

Function

handle: shishi handle as allocated by shishi_init(). apreq: AP-REQ to add authenticator field to. key: key to to use for encryption. keyusage: kerberos key usage value to use in encryption. authenticator: authenticator as allocated by shishi_authenticator(). Encrypts DER encoded authenticator using key and store it in the AP-REQ. Returns SHISHI_OK iff successful.

int shishi_apreq_set_ticket (Shishi * handle, Shishi_asn1 apreq, Shishi_asn1 ticket)

Function

handle: shishi handle as allocated by shishi_init(). apreq: AP-REQ to add ticket field to. ticket: input ticket to copy into AP-REQ ticket field. Copy ticket into AP-REQ. Returns SHISHI_OK iff successful.

int shishi_apreq_options (Shishi * handle, Shishi_asn1 apreq, int * flags)

Function

handle: shishi handle as allocated by shishi_init(). apreq: AP-REQ to get options from. flags: Output integer containing options from AP-REQ. Extract the AP-Options from AP-REQ into output integer. Returns SHISHI_OK iff successful.

int shishi_apreq_use_session_key_p (Shishi * handle, Shishi_asn1 apreq)

Function

handle: shishi handle as allocated by shishi_init(). apreq: AP-REQ as allocated by shishi_apreq(). Return non-0 iff the "Use session key" option is set in the AP-REQ. Returns SHISHI_OK iff successful.

int shishi_apreq_mutual_required_p (Shishi * handle, Shishi_asn1 apreq)

Function

handle: shishi handle as allocated by shishi_init(). apreq: AP-REQ as allocated by shishi_apreq(). Return non-0 iff the "Mutual required" option is set in the AP-REQ. Returns SHISHI_OK iff successful.

int shishi_apreq_options_set (Shishi * handle, Shishi_asn1 apreq, int options)

Function

handle: shishi handle as allocated by shishi_init(). apreq: AP-REQ as allocated by shishi_apreq(). options: Options to set in AP-REQ. Set the AP-Options in AP-REQ to indicate integer. Returns SHISHI_OK iff successful.

int shishi_apreq_options_add (Shishi * handle, Shishi_asn1 apreq, int option)

Function

handle: shishi handle as allocated by shishi_init(). apreq: AP-REQ as allocated by shishi_apreq(). option: Options to add in AP-REQ. Add the AP-Options in AP-REQ. Options not set in input parameter option are preserved in the AP-REQ. Returns SHISHI_OK iff successful.

int shishi_apreq_options_remove (Shishi * handle, Shishi_asn1 apreq, int option)

Function

handle: shishi handle as allocated by shishi_init(). apreq: AP-REQ as allocated by shishi_apreq(). option: Options to remove from AP-REQ. Remove the AP-Options from AP-REQ. Options not set in input parameter option are preserved in the AP-REQ. Returns SHISHI_OK iff successful.

int shishi_apreq_get_authenticator_etype (Shishi * handle, Shishi_asn1 apreq, int32_t * etype)

Function

handle: shishi handle as allocated by shishi_init(). etype: output variable that holds the value. Extract KDC-REP.enc-part.etype. Returns SHISHI_OK iff successful.

int shishi_apreq_get_ticket (Shishi * handle, Shishi_asn1 apreq, Shishi_asn1 * ticket)

Function

handle: shishi handle as allocated by shishi_init(). apreq: AP-REQ variable to get ticket from. ticket: output variable to hold extracted ticket. Extract ticket from AP-REQ. Returns SHISHI_OK iff successful.

Shishi_asn1 shishi_aprep (Shishi * handle)

Function

handle: shishi handle as allocated by shishi_init(). This function creates a new AP-REP, populated with some default values. Returns the authenticator or NULL on failure.

int shishi_aprep_print (Shishi * handle, FILE * fh, Shishi_asn1 aprep)

Function

handle: shishi handle as allocated by shishi_init(). fh: file handle open for writing. aprep: AP-REP to print. Print ASCII armored DER encoding of AP-REP to file. Returns SHISHI_OK iff successful.

int shishi_aprep_save (Shishi * handle, FILE * fh, Shishi_asn1 aprep)

Function

handle: shishi handle as allocated by shishi_init(). fh: file handle open for writing. aprep: AP-REP to save. Save DER encoding of AP-REP to file. Returns SHISHI_OK iff successful.

int shishi_aprep_to_file (Shishi * handle, Shishi_asn1 aprep, int filetype, char * filename)

Function

handle: shishi handle as allocated by shishi_init(). aprep: AP-REP to save. filetype: input variable specifying type of file to be written, see Shishi_filetype. filename: input variable with filename to write to. Write AP-REP to file in specified TYPE. The file will be truncated if it exists. Returns SHISHI_OK iff successful.

int shishi_aprep_parse (Shishi * handle, FILE * fh, Shishi_asn1 * aprep)

Function

handle: shishi handle as allocated by shishi_init(). fh: file handle open for reading. aprep: output variable with newly allocated AP-REP. Read ASCII armored DER encoded AP-REP from file and populate given variable. Returns SHISHI_OK iff successful.

int shishi_aprep_read (Shishi * handle, FILE * fh, Shishi_asn1 * aprep)

Function

handle: shishi handle as allocated by shishi_init(). fh: file handle open for reading. aprep: output variable with newly allocated AP-REP. Read DER encoded AP-REP from file and populate given variable. Returns SHISHI_OK iff successful.

int shishi_aprep_from_file (Shishi * handle, Shishi_asn1 * aprep, int filetype, char * filename)

Function

handle: shishi handle as allocated by shishi_init(). aprep: output variable with newly allocated AP-REP. filetype: input variable specifying type of file to be read, see Shishi_filetype. filename: input variable with filename to read from. Read AP-REP from file in specified TYPE. Returns SHISHI_OK iff successful.

int shishi_aprep_get_enc_part_etype (Shishi * handle, Shishi_asn1 aprep, int32_t * etype)

Function

handle: shishi handle as allocated by shishi_init(). aprep: AP-REP variable to get value from. etype: output variable that holds the value. Extract AP-REP.enc-part.etype. Returns SHISHI_OK iff successful.

Shishi_asn1 shishi_encapreppart (Shishi * handle)

Function

handle: shishi handle as allocated by shishi_init(). This function creates a new EncAPRepPart, populated with some default values. It uses the current time as returned by the system for the ctime and cusec fields. Returns the encapreppart or NULL on failure.

int shishi_encapreppart_print (Shishi * handle, FILE * fh, Shishi_asn1 encapreppart)

Function

handle: shishi handle as allocated by shishi_init(). fh: file handle open for writing. encapreppart: EncAPRepPart to print. Print ASCII armored DER encoding of EncAPRepPart to file. Returns SHISHI_OK iff successful.

int shishi_encapreppart_save (Shishi * handle, FILE * fh, Shishi_asn1 encapreppart)

Function

handle: shishi handle as allocated by shishi_init(). fh: file handle open for writing. encapreppart: EncAPRepPart to save. Save DER encoding of EncAPRepPart to file. Returns SHISHI_OK iff successful.

int shishi_encapreppart_to_file (Shishi * handle, Shishi_asn1 encapreppart, int filetype, char * filename)

Function

handle: shishi handle as allocated by shishi_init(). encapreppart: EncAPRepPart to save. filetype: input variable specifying type of file to be written, see Shishi_filetype. filename: input variable with filename to write to. Write EncAPRepPart to file in specified TYPE. The file will be truncated if it exists. Returns SHISHI_OK iff successful.

int shishi_encapreppart_parse (Shishi * handle, FILE * fh, Shishi_asn1 * encapreppart)

Function

handle: shishi handle as allocated by shishi_init(). fh: file handle open for reading. encapreppart: output variable with newly allocated EncAPRepPart. Read ASCII armored DER encoded EncAPRepPart from file and populate given variable. Returns SHISHI_OK iff successful.

int shishi_encapreppart_read (Shishi * handle, FILE * fh, Shishi_asn1 * encapreppart)

Function

handle: shishi handle as allocated by shishi_init(). fh: file handle open for reading. encapreppart: output variable with newly allocated EncAPRepPart. Read DER encoded EncAPRepPart from file and populate given variable. Returns SHISHI_OK iff successful.

int shishi_encapreppart_from_file (Shishi * handle, Shishi_asn1 * encapreppart, int filetype, char * filename)

Function

handle: shishi handle as allocated by shishi_init(). encapreppart: output variable with newly allocated EncAPRepPart. filetype: input variable specifying type of file to be read, see Shishi_filetype. filename: input variable with filename to read from. Read EncAPRepPart from file in specified TYPE. Returns SHISHI_OK iff successful.

int shishi_encapreppart_get_key (Shishi * handle, Shishi_asn1 encapreppart, int32_t * keytype, char * keyvalue, size_t * keyvalue_len)

Function

handle: shishi handle as allocated by shishi_init(). encapreppart: input EncAPRepPart variable. keytype: output variable that holds key type. keyvalue: output array with key. keyvalue_len: on input, maximum size of output array with key, on output, holds the actual size of output array with key. Extract the subkey from the encrypted AP-REP part. Returns SHISHI_OK iff succesful.

int shishi_encapreppart_ctime (Shishi * handle, Shishi_asn1 encapreppart, char ** ctime)

Function

handle: shishi handle as allocated by shishi_init(). encapreppart: EncAPRepPart as allocated by shishi_encapreppart(). ctime: newly allocated zero-terminated character array with client time. Extract client time from EncAPRepPart. Returns SHISHI_OK iff successful.

int shishi_encapreppart_ctime_set (Shishi * handle, Shishi_asn1 encapreppart, char * ctime)

Function

handle: shishi handle as allocated by shishi_init(). encapreppart: EncAPRepPart as allocated by shishi_encapreppart(). ctime: string with generalized time value to store in EncAPRepPart. Store client time in EncAPRepPart. Returns SHISHI_OK iff successful.

int shishi_encapreppart_cusec_get (Shishi * handle, Shishi_asn1 encapreppart, int * cusec)

Function

handle: shishi handle as allocated by shishi_init(). encapreppart: EncAPRepPart as allocated by shishi_encapreppart(). cusec: output integer with client microseconds field. Extract client microseconds field from EncAPRepPart. Returns SHISHI_OK iff successful.

int shishi_encapreppart_cusec_set (Shishi * handle, Shishi_asn1 encapreppart, int cusec)

Function

handle: shishi handle as allocated by shishi_init(). encapreppart: EncAPRepPart as allocated by shishi_encapreppart(). cusec: client microseconds to set in authenticator, 0-999999. Set the cusec field in the Authenticator. Returns SHISHI_OK iff successful.

int shishi_encapreppart_seqnumber_get (Shishi * handle, Shishi_asn1 encapreppart, uint32_t * seqnumber)

Function

handle: shishi handle as allocated by shishi_init(). encapreppart: EncAPRepPart as allocated by shishi_encapreppart(). seqnumber: output integer with sequence number field. Extract sequence number field from EncAPRepPart. Returns SHISHI_OK iff successful.

int shishi_encapreppart_time_copy (Shishi * handle, Shishi_asn1 encapreppart, Shishi_asn1 authenticator)

Function

handle: shishi handle as allocated by shishi_init(). encapreppart: EncAPRepPart as allocated by shishi_encapreppart(). authenticator: Authenticator to copy time fields from. Copy time fields from Authenticator into EncAPRepPart. Returns SHISHI_OK iff successful.

5.5 SAFE and PRIV Functions

The "KRB-SAFE" is an ASN.1 structure used by application client and servers to exchange integrity protected data. The integrity protection is keyed, usually with a key agreed on via the AP exchange (see AP-REQ and AP-REP Functions). The following illustrates the KRB-SAFE ASN.1 structure.

   KRB-SAFE        ::= [APPLICATION 20] SEQUENCE {
           pvno            [0] INTEGER (5),
           msg-type        [1] INTEGER (20),
           safe-body       [2] KRB-SAFE-BODY,
           cksum           [3] Checksum
   }

   KRB-SAFE-BODY   ::= SEQUENCE {
           user-data       [0] OCTET STRING,
           timestamp       [1] KerberosTime OPTIONAL,
           usec            [2] Microseconds OPTIONAL,
           seq-number      [3] UInt32 OPTIONAL,
           s-address       [4] HostAddress,
           r-address       [5] HostAddress OPTIONAL
   }

int shishi_safe (Shishi * handle, Shishi_safe ** safe)

Function

handle: shishi handle as allocated by shishi_init(). safe: pointer to new structure that holds information about SAFE exchange Create a new SAFE exchange. Returns SHISHI_OK iff successful.

void shishi_safe_done (Shishi_safe * safe)

Function

safe: structure that holds information about SAFE exchange Deallocate resources associated with SAFE exchange. This should be called by the application when it no longer need to utilize the SAFE exchange handle.

Shishi_key * shishi_safe_key (Shishi_safe * safe)

Function

safe: structure that holds information about SAFE exchange Returns the key used in the SAFE exchange, or NULL if not yet set or an error occured.

void shishi_safe_key_set (Shishi_safe * safe, Shishi_key * key)

Function

safe: structure that holds information about SAFE exchange key: key to store in SAFE. Set the Key in the SAFE exchange.

Shishi_asn1 shishi_safe_safe (Shishi_safe * safe)

Function

safe: structure that holds information about SAFE exchange Returns the ASN.1 safe in the SAFE exchange, or NULL if not yet set or an error occured.

void shishi_safe_safe_set (Shishi_safe * safe, Shishi_asn1 asn1safe)

Function

safe: structure that holds information about SAFE exchange asn1safe: KRB-SAFE to store in SAFE exchange. Set the KRB-SAFE in the SAFE exchange.

int shishi_safe_safe_der (Shishi_safe * safe, char ** out, size_t * outlen)

Function

safe: safe as allocated by shishi_safe(). out: output array with newly allocated DER encoding of SAFE. outlen: length of output array with DER encoding of SAFE. DER encode SAFE structure. Typically shishi_safe_build() is used to build the SAFE structure first. out is allocated by this function, and it is the responsibility of caller to deallocate it. Returns SHISHI_OK iff successful.

int shishi_safe_safe_der_set (Shishi_safe * safe, char * der, size_t derlen)

Function

safe: safe as allocated by shishi_safe(). der: input array with DER encoded KRB-SAFE. derlen: length of input array with DER encoded KRB-SAFE. DER decode KRB-SAFE and set it SAFE exchange. If decoding fails, the KRB-SAFE in the SAFE exchange remains. Returns SHISHI_OK.

int shishi_safe_print (Shishi * handle, FILE * fh, Shishi_asn1 safe)

Function

handle: shishi handle as allocated by shishi_init(). fh: file handle open for writing. safe: SAFE to print. Print ASCII armored DER encoding of SAFE to file. Returns SHISHI_OK iff successful.

int shishi_safe_save (Shishi * handle, FILE * fh, Shishi_asn1 safe)

Function

handle: shishi handle as allocated by shishi_init(). fh: file handle open for writing. safe: SAFE to save. Save DER encoding of SAFE to file. Returns SHISHI_OK iff successful.

int shishi_safe_to_file (Shishi * handle, Shishi_asn1 safe, int filetype, char * filename)

Function

handle: shishi handle as allocated by shishi_init(). safe: SAFE to save. filetype: input variable specifying type of file to be written, see Shishi_filetype. filename: input variable with filename to write to. Write SAFE to file in specified TYPE. The file will be truncated if it exists. Returns SHISHI_OK iff successful.

int shishi_safe_parse (Shishi * handle, FILE * fh, Shishi_asn1 * safe)

Function

handle: shishi handle as allocated by shishi_init(). fh: file handle open for reading. safe: output variable with newly allocated SAFE. Read ASCII armored DER encoded SAFE from file and populate given variable. Returns SHISHI_OK iff successful.

int shishi_safe_read (Shishi * handle, FILE * fh, Shishi_asn1 * safe)

Function

handle: shishi handle as allocated by shishi_init(). fh: file handle open for reading. safe: output variable with newly allocated SAFE. Read DER encoded SAFE from file and populate given variable. Returns SHISHI_OK iff successful.

int shishi_safe_from_file (Shishi * handle, Shishi_asn1 * safe, int filetype, const char * filename)

Function

handle: shishi handle as allocated by shishi_init(). safe: output variable with newly allocated SAFE. filetype: input variable specifying type of file to be read, see Shishi_filetype. filename: input variable with filename to read from. Read SAFE from file in specified TYPE. Returns SHISHI_OK iff successful.

int shishi_safe_cksum (Shishi * handle, Shishi_asn1 safe, int32_t * cksumtype, char ** cksum, size_t * cksumlen)

Function

handle: shishi handle as allocated by shishi_init(). safe: safe as allocated by shishi_safe(). cksumtype: output checksum type. cksum: output array with newly allocated checksum data from SAFE. cksumlen: output size of output checksum data buffer. Read checksum value from KRB-SAFE. cksum is allocated by this function, and it is the responsibility of caller to deallocate it. Returns SHISHI_OK iff successful.

int shishi_safe_set_cksum (Shishi * handle, Shishi_asn1 safe, int32_t cksumtype, const char * cksum, size_t cksumlen)

Function

handle: shishi handle as allocated by shishi_init(). safe: safe as allocated by shishi_safe(). cksumtype: input checksum type to store in SAFE. cksum: input checksum data to store in SAFE. cksumlen: size of input checksum data to store in SAFE. Store checksum value in SAFE. A checksum is usually created by calling shishi_checksum() on some application specific data using the key from the ticket that is being used. To save time, you may want to use shishi_safe_build() instead, which calculates the checksum and calls this function in one step. Returns SHISHI_OK iff successful.

int shishi_safe_user_data (Shishi * handle, Shishi_asn1 safe, char ** userdata, size_t * userdatalen)

Function

handle: shishi handle as allocated by shishi_init(). safe: safe as allocated by shishi_safe(). userdata: output array with newly allocated user data from KRB-SAFE. userdatalen: output size of output user data buffer. Read user data value from KRB-SAFE. userdata is allocated by this function, and it is the responsibility of caller to deallocate it. Returns SHISHI_OK iff successful.

int shishi_safe_set_user_data (Shishi * handle, Shishi_asn1 safe, const char * userdata, size_t userdatalen)

Function

handle: shishi handle as allocated by shishi_init(). safe: safe as allocated by shishi_safe(). userdata: input user application to store in SAFE. userdatalen: size of input user application to store in SAFE. Set the application data in SAFE. Returns SHISHI_OK iff successful.

int shishi_safe_build (Shishi_safe * safe, Shishi_key * key)

Function

safe: safe as allocated by shishi_safe(). key: key for session, used to compute checksum. Build checksum and set it in KRB-SAFE. Note that this follows RFC 1510bis and is incompatible with RFC 1510, although presumably few implementations use the RFC1510 algorithm. Returns SHISHI_OK iff successful.

int shishi_safe_verify (Shishi_safe * safe, Shishi_key * key)

Function

safe: safe as allocated by shishi_safe(). key: key for session, used to verify checksum. Verify checksum in KRB-SAFE. Note that this follows RFC 1510bis and is incompatible with RFC 1510, although presumably few implementations use the RFC1510 algorithm. Returns SHISHI_OK iff successful, SHISHI_SAFE_BAD_KEYTYPE if an incompatible key type is used, or SHISHI_SAFE_VERIFY_FAILED if the actual verification failed.

The "KRB-PRIV" is an ASN.1 structure used by application client and servers to exchange confidential data. The confidentiality is keyed, usually with a key agreed on via the AP exchange (see AP-REQ and AP-REP Functions). The following illustrates the KRB-PRIV ASN.1 structure.

   KRB-PRIV        ::= [APPLICATION 21] SEQUENCE {
           pvno            [0] INTEGER (5),
           msg-type        [1] INTEGER (21),
                           -- NOTE: there is no [2] tag
           enc-part        [3] EncryptedData -- EncKrbPrivPart
   }

   EncKrbPrivPart  ::= [APPLICATION 28] SEQUENCE {
           user-data       [0] OCTET STRING,
           timestamp       [1] KerberosTime OPTIONAL,
           usec            [2] Microseconds OPTIONAL,
           seq-number      [3] UInt32 OPTIONAL,
           s-address       [4] HostAddress -- sender's addr --,
           r-address       [5] HostAddress OPTIONAL -- recip's addr
   }

int shishi_priv (Shishi * handle, Shishi_priv ** priv)

Function

handle: shishi handle as allocated by shishi_init(). priv: pointer to new structure that holds information about PRIV exchange Create a new PRIV exchange. Returns SHISHI_OK iff successful.

void shishi_priv_done (Shishi_priv * priv)

Function

priv: structure that holds information about PRIV exchange Deallocate resources associated with PRIV exchange. This should be called by the application when it no longer need to utilize the PRIV exchange handle.

Shishi_key * shishi_priv_key (Shishi_priv * priv)

Function

priv: structure that holds information about PRIV exchange Returns the key used in the PRIV exchange, or NULL if not yet set or an error occured.

void shishi_priv_key_set (Shishi_priv * priv, Shishi_key * key)

Function

priv: structure that holds information about PRIV exchange key: key to store in PRIV. Set the Key in the PRIV exchange.

Shishi_asn1 shishi_priv_priv (Shishi_priv * priv)

Function

priv: structure that holds information about PRIV exchange Returns the ASN.1 priv in the PRIV exchange, or NULL if not yet set or an error occured.

void shishi_priv_priv_set (Shishi_priv * priv, Shishi_asn1 asn1priv)

Function

priv: structure that holds information about PRIV exchange asn1priv: KRB-PRIV to store in PRIV exchange. Set the KRB-PRIV in the PRIV exchange.

int shishi_priv_priv_der (Shishi_priv * priv, char ** out, size_t * outlen)

Function

priv: priv as allocated by shishi_priv(). out: output array with newly allocated DER encoding of PRIV. outlen: length of output array with DER encoding of PRIV. DER encode PRIV structure. Typically shishi_priv_build() is used to build the PRIV structure first. out is allocated by this function, and it is the responsibility of caller to deallocate it. Returns SHISHI_OK iff successful.

int shishi_priv_priv_der_set (Shishi_priv * priv, char * der, size_t derlen)

Function

priv: priv as allocated by shishi_priv(). der: input array with DER encoded KRB-PRIV. derlen: length of input array with DER encoded KRB-PRIV. DER decode KRB-PRIV and set it PRIV exchange. If decoding fails, the KRB-PRIV in the PRIV exchange remains. Returns SHISHI_OK.

Shishi_asn1 shishi_priv_encprivpart (Shishi_priv * priv)

Function

priv: structure that holds information about PRIV exchange Returns the ASN.1 encprivpart in the PRIV exchange, or NULL if not yet set or an error occured.

void shishi_priv_encprivpart_set (Shishi_priv * priv, Shishi_asn1 asn1encprivpart)

Function

priv: structure that holds information about PRIV exchange asn1encprivpart: ENCPRIVPART to store in PRIV exchange. Set the ENCPRIVPART in the PRIV exchange.

int shishi_priv_encprivpart_der (Shishi_priv * priv, char ** out, size_t * outlen)

Function

priv: priv as allocated by shishi_priv(). out: output array with newly allocated DER encoding of ENCPRIVPART. outlen: length of output array with DER encoding of ENCPRIVPART. DER encode ENCPRIVPART structure. Typically shishi_encprivpart_build() is used to build the ENCPRIVPART structure first. out is allocated by this function, and it is the responsibility of caller to deallocate it. Returns SHISHI_OK iff successful.

int shishi_priv_encprivpart_der_set (Shishi_priv * priv, char * der, size_t derlen)

Function

priv: priv as allocated by shishi_priv(). der: input array with DER encoded ENCPRIVPART. derlen: length of input array with DER encoded ENCPRIVPART. DER decode ENCPRIVPART and set it PRIV exchange. If decoding fails, the ENCPRIVPART in the PRIV exchange remains. Returns SHISHI_OK.

int shishi_priv_print (Shishi * handle, FILE * fh, Shishi_asn1 priv)

Function

handle: shishi handle as allocated by shishi_init(). fh: file handle open for writing. priv: PRIV to print. Print ASCII armored DER encoding of PRIV to file. Returns SHISHI_OK iff successful.

int shishi_priv_save (Shishi * handle, FILE * fh, Shishi_asn1 priv)

Function

handle: shishi handle as allocated by shishi_init(). fh: file handle open for writing. priv: PRIV to save. Save DER encoding of PRIV to file. Returns SHISHI_OK iff successful.

int shishi_priv_to_file (Shishi * handle, Shishi_asn1 priv, int filetype, char * filename)

Function

handle: shishi handle as allocated by shishi_init(). priv: PRIV to save. filetype: input variable specifying type of file to be written, see Shishi_filetype. filename: input variable with filename to write to. Write PRIV to file in specified TYPE. The file will be truncated if it exists. Returns SHISHI_OK iff successful.

int shishi_priv_parse (Shishi * handle, FILE * fh, Shishi_asn1 * priv)

Function

handle: shishi handle as allocated by shishi_init(). fh: file handle open for reading. priv: output variable with newly allocated PRIV. Read ASCII armored DER encoded PRIV from file and populate given variable. Returns SHISHI_OK iff successful.

int shishi_priv_read (Shishi * handle, FILE * fh, Shishi_asn1 * priv)

Function

handle: shishi handle as allocated by shishi_init(). fh: file handle open for reading. priv: output variable with newly allocated PRIV. Read DER encoded PRIV from file and populate given variable. Returns SHISHI_OK iff successful.

int shishi_priv_from_file (Shishi * handle, Shishi_asn1 * priv, int filetype, const char * filename)

Function

handle: shishi handle as allocated by shishi_init(). priv: output variable with newly allocated PRIV. filetype: input variable specifying type of file to be read, see Shishi_filetype. filename: input variable with filename to read from. Read PRIV from file in specified TYPE. Returns SHISHI_OK iff successful.

int shishi_priv_enc_part_etype (Shishi * handle, Shishi_asn1 priv, int32_t * etype)

Function

handle: shishi handle as allocated by shishi_init(). priv: PRIV variable to get value from. etype: output variable that holds the value. Extract PRIV.enc-part.etype. Returns SHISHI_OK iff successful.

int shishi_priv_set_enc_part (Shishi * handle, Shishi_asn1 priv, int32_t etype, const char * encpart, size_t encpartlen)

Function

handle: shishi handle as allocated by shishi_init(). priv: priv as allocated by shishi_priv(). etype: input encryption type to store in PRIV. encpart: input encrypted data to store in PRIV. encpartlen: size of input encrypted data to store in PRIV. Store encrypted data in PRIV. The encrypted data is usually created by calling shishi_encrypt() on some application specific data using the key from the ticket that is being used. To save time, you may want to use shishi_priv_build() instead, which encryptes the data and calls this function in one step. Returns SHISHI_OK iff successful.

int shishi_encprivpart_user_data (Shishi * handle, Shishi_asn1 encprivpart, char ** userdata, size_t * userdatalen)

Function

handle: shishi handle as allocated by shishi_init(). encprivpart: encprivpart as allocated by shishi_priv(). userdata: output array with newly allocated user data from KRB-PRIV. userdatalen: output size of output user data buffer. Read user data value from KRB-PRIV. userdata is allocated by this function, and it is the responsibility of caller to deallocate it. Returns SHISHI_OK iff successful.

int shishi_encprivpart_set_user_data (Shishi * handle, Shishi_asn1 encprivpart, const char * userdata, size_t userdatalen)

Function

handle: shishi handle as allocated by shishi_init(). encprivpart: encprivpart as allocated by shishi_priv(). userdata: input user application to store in PRIV. userdatalen: size of input user application to store in PRIV. Set the application data in PRIV. Returns SHISHI_OK iff successful.

int shishi_priv_build (Shishi_priv * priv, Shishi_key * key)

Function

priv: priv as allocated by shishi_priv(). key: key for session, used to encrypt data. Build checksum and set it in KRB-PRIV. Note that this follows RFC 1510bis and is incompatible with RFC 1510, although presumably few implementations use the RFC1510 algorithm. Returns SHISHI_OK iff successful.

int shishi_priv_process (Shishi_priv * priv, Shishi_key * key)

Function

priv: priv as allocated by shishi_priv(). key: key to use to decrypt EncPrivPart. Decrypt encrypted data in KRB-PRIV and set the EncPrivPart in the PRIV exchange. Returns SHISHI_OK iff successful, SHISHI_PRIV_BAD_KEYTYPE if an incompatible key type is used, or SHISHI_CRYPTO_ERROR if the actual decryption failed.

5.6 Ticket Functions

int shishi_tkt (Shishi * handle, Shishi_tkt ** tkt)

Function

handle: shishi handle as allocated by shishi_init(). tkt: output variable with newly allocated ticket. Create a new ticket handle. Returns SHISHI_OK iff successful.

Shishi_tkt * shishi_tkt2 (Shishi * handle, Shishi_asn1 ticket, Shishi_asn1 enckdcreppart, Shishi_asn1 kdcrep)

Function

handle: shishi handle as allocated by shishi_init(). ticket: input variable with ticket. enckdcreppart: input variable with auxilliary ticket information. kdcrep: input variable with KDC-REP ticket information. Create a new ticket handle. Returns new ticket handle, or NULL on error.

void shishi_tkt_done (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Deallocate resources associated with ticket. The ticket must not be used again after this call.

Shishi_asn1 shishi_tkt_ticket (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Returns actual ticket.

Shishi_asn1 shishi_tkt_enckdcreppart (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Returns auxilliary ticket information.

void shishi_tkt_enckdcreppart_set (Shishi_tkt * tkt, Shishi_asn1 enckdcreppart)

Function

enckdcreppart: EncKDCRepPart to store in Ticket. Set the EncKDCRepPart in the Ticket.

Shishi_asn1 shishi_tkt_kdcrep (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Returns KDC-REP information.

Shishi_asn1 shishi_tkt_encticketpart (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Returns EncTicketPart information.

void shishi_tkt_encticketpart_set (Shishi_tkt * tkt, Shishi_asn1 encticketpart)

Function

tkt: input variable with ticket info. encticketpart: encticketpart to store in ticket. Set the EncTicketPart in the Ticket.

Shishi_key * shishi_tkt_key (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Returns key extracted from enckdcreppart.

int shishi_tkt_key_set (Shishi_tkt * tkt, Shishi_key * key)

Function

tkt: input variable with ticket info. key: key to store in ticket. Set the key in the EncTicketPart. Returns SHISHI_OK iff successful.

int shishi_tkt_client (Shishi_tkt * tkt, char * client, size_t * clientlen)

Function

tkt: input variable with ticket info. client: output buffer that holds client name of ticket. clientlen: on input, maximum size of output buffer, on output, actual size of output buffer. Returns client principal of ticket.

int shishi_tkt_client_p (Shishi_tkt * tkt, const char * client)

Function

tkt: input variable with ticket info. client: client name of ticket. Determine if ticket is for specified client. Returns non-0 iff ticket is for specified client.

int shishi_tkt_cnamerealm_p (Shishi_tkt * tkt, const char * client)

Function

tkt: input variable with ticket info. client: principal name (client name and realm) of ticket. Determine if ticket is for specified client principal. Returns non-0 iff ticket is for specified client principal.

int shishi_tkt_realm (Shishi_tkt * tkt, char ** realm, size_t * realmlen)

Function

tkt: input variable with ticket info. realm: pointer to newly allocated character array with realm name. realmlen: length of newly allocated character array with realm name. Extract realm of server in ticket. Returns SHISHI_OK iff successful.

int shishi_tkt_server_p (Shishi_tkt * tkt, const char * server)

Function

tkt: input variable with ticket info. server: server name of ticket. Determine if ticket is for specified server. Returns non-0 iff ticket is for specified server.

int shishi_tkt_flags (Shishi_tkt * tkt, int * flags)

Function

tkt: input variable with ticket info. flags: pointer to output integer with flags. Extract flags in ticket. Returns SHISHI_OK iff successful.

int shishi_tkt_flags_set (Shishi_tkt * tkt, int flags)

Function

tkt: input variable with ticket info. flags: integer with flags to store in ticket. Set flags in ticket. Note that this reset any already existing flags. Returns SHISHI_OK iff successful.

int shishi_tkt_forwardable_p (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Determine if ticket is forwardable. The FORWARDABLE flag in a ticket is normally only interpreted by the ticket-granting service. It can be ignored by application servers. The FORWARDABLE flag has an interpretation similar to that of the PROXIABLE flag, except ticket-granting tickets may also be issued with different network addresses. This flag is reset by default, but users MAY request that it be set by setting the FORWARDABLE option in the AS request when they request their initial ticket-granting ticket. Returns non-0 iff forwardable flag is set in ticket.

int shishi_tkt_forwarded_p (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Determine if ticket is forwarded. The FORWARDED flag is set by the TGS when a client presents a ticket with the FORWARDABLE flag set and requests a forwarded ticket by specifying the FORWARDED KDC option and supplying a set of addresses for the new ticket. It is also set in all tickets issued based on tickets with the FORWARDED flag set. Application servers may choose to process FORWARDED tickets differently than non-FORWARDED tickets. Returns non-0 iff forwarded flag is set in ticket.

int shishi_tkt_proxiable_p (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Determine if ticket is proxiable. The PROXIABLE flag in a ticket is normally only interpreted by the ticket-granting service. It can be ignored by application servers. When set, this flag tells the ticket-granting server that it is OK to issue a new ticket (but not a ticket-granting ticket) with a different network address based on this ticket. This flag is set if requested by the client on initial authentication. By default, the client will request that it be set when requesting a ticket-granting ticket, and reset when requesting any other ticket. Returns non-0 iff proxiable flag is set in ticket.

int shishi_tkt_proxy_p (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Determine if ticket is proxy ticket. The PROXY flag is set in a ticket by the TGS when it issues a proxy ticket. Application servers MAY check this flag and at their option they MAY require additional authentication from the agent presenting the proxy in order to provide an audit trail. Returns non-0 iff proxy flag is set in ticket.

int shishi_tkt_may_postdate_p (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Determine if ticket may be used to grant postdated tickets. The MAY-POSTDATE flag in a ticket is normally only interpreted by the ticket-granting service. It can be ignored by application servers. This flag MUST be set in a ticket-granting ticket in order to issue a postdated ticket based on the presented ticket. It is reset by default; it MAY be requested by a client by setting the ALLOW- POSTDATE option in the KRB_AS_REQ message. This flag does not allow a client to obtain a postdated ticket-granting ticket; postdated ticket-granting tickets can only by obtained by requesting the postdating in the KRB_AS_REQ message. The life (endtime-starttime) of a postdated ticket will be the remaining life of the ticket-granting ticket at the time of the request, unless the RENEWABLE option is also set, in which case it can be the full life (endtime-starttime) of the ticket-granting ticket. The KDC MAY limit how far in the future a ticket may be postdated. Returns non-0 iff may-postdate flag is set in ticket.

int shishi_tkt_postdated_p (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Determine if ticket is postdated. The POSTDATED flag indicates that a ticket has been postdated. The application server can check the authtime field in the ticket to see when the original authentication occurred. Some services MAY choose to reject postdated tickets, or they may only accept them within a certain period after the original authentication. When the KDC issues a POSTDATED ticket, it will also be marked as INVALID, so that the application client MUST present the ticket to the KDC to be validated before use. Returns non-0 iff postdated flag is set in ticket.

int shishi_tkt_invalid_p (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Determine if ticket is invalid. The INVALID flag indicates that a ticket is invalid. Application servers MUST reject tickets which have this flag set. A postdated ticket will be issued in this form. Invalid tickets MUST be validated by the KDC before use, by presenting them to the KDC in a TGS request with the VALIDATE option specified. The KDC will only validate tickets after their starttime has passed. The validation is required so that postdated tickets which have been stolen before their starttime can be rendered permanently invalid (through a hot-list mechanism). Returns non-0 iff invalid flag is set in ticket.

int shishi_tkt_renewable_p (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Determine if ticket is renewable. The RENEWABLE flag in a ticket is normally only interpreted by the ticket-granting service (discussed below in section 3.3). It can usually be ignored by application servers. However, some particularly careful application servers MAY disallow renewable tickets. Returns non-0 iff renewable flag is set in ticket.

int shishi_tkt_initial_p (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Determine if ticket was issued using AS exchange. The INITIAL flag indicates that a ticket was issued using the AS protocol, rather than issued based on a ticket-granting ticket. Application servers that want to require the demonstrated knowledge of a client's secret key (e.g. a password-changing program) can insist that this flag be set in any tickets they accept, and thus be assured that the client's key was recently presented to the application client. Returns non-0 iff initial flag is set in ticket.

int shishi_tkt_pre_authent_p (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Determine if ticket was pre-authenticated. The PRE-AUTHENT and HW-AUTHENT flags provide additional information about the initial authentication, regardless of whether the current ticket was issued directly (in which case INITIAL will also be set) or issued on the basis of a ticket-granting ticket (in which case the INITIAL flag is clear, but the PRE-AUTHENT and HW-AUTHENT flags are carried forward from the ticket-granting ticket). Returns non-0 iff pre-authent flag is set in ticket.

int shishi_tkt_hw_authent_p (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Determine if ticket is authenticated using a hardware token. The PRE-AUTHENT and HW-AUTHENT flags provide additional information about the initial authentication, regardless of whether the current ticket was issued directly (in which case INITIAL will also be set) or issued on the basis of a ticket-granting ticket (in which case the INITIAL flag is clear, but the PRE-AUTHENT and HW-AUTHENT flags are carried forward from the ticket-granting ticket). Returns non-0 iff hw-authent flag is set in ticket.

int shishi_tkt_transited_policy_checked_p (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Determine if ticket has been policy checked for transit. In Kerberos, the application server is ultimately responsible for accepting or rejecting authentication and SHOULD check that only suitably trusted KDCs are relied upon to authenticate a principal. The transited field in the ticket identifies which realms (and thus which KDCs) were involved in the authentication process and an application server would normally check this field. If any of these are untrusted to authenticate the indicated client principal (probably determined by a realm-based policy), the authentication attempt MUST be rejected. The presence of trusted KDCs in this list does not provide any guarantee; an untrusted KDC may have fabricated the list. While the end server ultimately decides whether authentication is valid, the KDC for the end server's realm MAY apply a realm specific policy for validating the transited field and accepting credentials for cross-realm authentication. When the KDC applies such checks and accepts such cross-realm authentication it will set the TRANSITED-POLICY-CHECKED flag in the service tickets it issues based on the cross-realm TGT. A client MAY request that the KDCs not check the transited field by setting the DISABLE-TRANSITED-CHECK flag. KDCs are encouraged but not required to honor this flag. Application servers MUST either do the transited-realm checks themselves, or reject cross-realm tickets without TRANSITED-POLICY- CHECKED set. Returns non-0 iff transited-policy-checked flag is set in ticket.

int shishi_tkt_ok_as_delegate_p (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Determine if ticket is ok as delegated ticket. The copy of the ticket flags in the encrypted part of the KDC reply may have the OK-AS-DELEGATE flag set to indicates to the client that the server specified in the ticket has been determined by policy of the realm to be a suitable recipient of delegation. A client can use the presence of this flag to help it make a decision whether to delegate credentials (either grant a proxy or a forwarded ticket- granting ticket) to this server. It is acceptable to ignore the value of this flag. When setting this flag, an administrator should consider the security and placement of the server on which the service will run, as well as whether the service requires the use of delegated credentials. Returns non-0 iff ok-as-delegate flag is set in ticket.

int shishi_tkt_keytype (Shishi_tkt * tkt, int32_t * etype)

Function

tkt: input variable with ticket info. etype: pointer to encryption type that is set, see Shishi_etype. Extract encryption type of key in ticket (really EncKDCRepPart). Returns SHISHI_OK iff successful.

int shishi_tkt_keytype_p (Shishi_tkt * tkt, int32_t etype)

Function

tkt: input variable with ticket info. etype: encryption type, see Shishi_etype. Determine if key in ticket (really EncKDCRepPart) is of specified key type (really encryption type). Returns non-0 iff key in ticket is of specified encryption type.

time_t shishi_tkt_lastreqc (Shishi_tkt * tkt, Shishi_lrtype lrtype)

Function

tkt: input variable with ticket info. lrtype: lastreq type to extract, see Shishi_lrtype. E.g., SHISHI_LRTYPE_LAST_REQUEST. Extract C time corresponding to given lastreq type field in the ticket. Returns C time interpretation of the specified lastreq field, or (time_t) -1.

time_t shishi_tkt_authctime (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Extract C time corresponding to the authtime field. The field holds the time when the original authentication took place that later resulted in this ticket. Returns C time interpretation of the endtime in ticket.

time_t shishi_tkt_startctime (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Extract C time corresponding to the starttime field. The field holds the time where the ticket start to be valid (typically in the past). Returns C time interpretation of the endtime in ticket.

time_t shishi_tkt_endctime (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Extract C time corresponding to the endtime field. The field holds the time where the ticket stop being valid. Returns C time interpretation of the endtime in ticket.

time_t shishi_tkt_renew_tillc (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Extract C time corresponding to the renew-till field. The field holds the time where the ticket stop being valid for renewal. Returns C time interpretation of the renew-till in ticket.

int shishi_tkt_valid_at_time_p (Shishi_tkt * tkt, time_t now)

Function

tkt: input variable with ticket info. now: time to check for. Determine if ticket is valid at a specific point in time. Returns non-0 iff ticket is valid (not expired and after starttime) at specified time.

int shishi_tkt_valid_now_p (Shishi_tkt * tkt)

Function

tkt: input variable with ticket info. Determine if ticket is valid now. Returns 0 iff ticket is invalid (expired or not yet valid).

void shishi_tkt_lastreq_pretty_print (Shishi_tkt * tkt, FILE * fh)

Function

tkt: input variable with ticket info. fh: file handle open for writing. Print a human readable representation of the various lastreq fields in the ticket (really EncKDCRepPart).

void shishi_tkt_pretty_print (Shishi_tkt * tkt, FILE * fh)

Function

tkt: input variable with ticket info. fh: file handle open for writing. Print a human readable representation of a ticket to file handle.

5.7 AS Functions

The Authentication Service (AS) is used to get an initial ticket using e.g. your password. The following illustrates the AS-REQ and AS-REP ASN.1 structures.

-- Request --

AS-REQ		::= KDC-REQ {10}

KDC-REQ {INTEGER:tagnum}	::= [APPLICATION tagnum] SEQUENCE {
	pvno		[1] INTEGER (5) -- first tag is [1], not [0] --,
	msg-type	[2] INTEGER (tagnum),
	padata		[3] SEQUENCE OF PA-DATA OPTIONAL,
	req-body	[4] KDC-REQ-BODY
}

KDC-REQ-BODY	::= SEQUENCE {
	kdc-options		[0] KDCOptions,
	cname			[1] PrincipalName OPTIONAL
				    -- Used only in AS-REQ --,
	realm			[2] Realm
				    -- Server's realm
				    -- Also client's in AS-REQ --,
	sname			[3] PrincipalName OPTIONAL,
	from			[4] KerberosTime OPTIONAL,
	till			[5] KerberosTime,
	rtime			[6] KerberosTime OPTIONAL,
	nonce			[7] UInt32,
	etype			[8] SEQUENCE OF Int32 -- EncryptionType
				    -- in preference order --,
	addresses		[9] HostAddresses OPTIONAL,
	enc-authorization-data	[10] EncryptedData {
					AuthorizationData,
					{ keyuse-TGSReqAuthData-sesskey
					  | keyuse-TGSReqAuthData-subkey }
				     } OPTIONAL,
	additional-tickets	[11] SEQUENCE OF Ticket OPTIONAL
}

-- Reply --

AS-REP		::= KDC-REP {11, EncASRepPart, {keyuse-EncASRepPart}}

KDC-REP {INTEGER:tagnum,
	 TypeToEncrypt,
	 UInt32:KeyUsages}	::= [APPLICATION tagnum] SEQUENCE {
	pvno		[0] INTEGER (5),
	msg-type	[1] INTEGER (tagnum),
	padata		[2] SEQUENCE OF PA-DATA OPTIONAL,
	crealm		[3] Realm,
	cname		[4] PrincipalName,
	ticket		[5] Ticket,
	enc-part	[6] EncryptedData {TypeToEncrypt, KeyUsages}
}

EncASRepPart	::= [APPLICATION 25] EncKDCRepPart

EncKDCRepPart	::= SEQUENCE {
	key		[0] EncryptionKey,
	last-req	[1] LastReq,
	nonce		[2] UInt32,
	key-expiration	[3] KerberosTime OPTIONAL,
	flags		[4] TicketFlags,
	authtime	[5] KerberosTime,
	starttime	[6] KerberosTime OPTIONAL,
	endtime		[7] KerberosTime,
	renew-till	[8] KerberosTime OPTIONAL,
	srealm		[9] Realm,
	sname		[10] PrincipalName,
	caddr		[11] HostAddresses OPTIONAL
}

int shishi_as (Shishi * handle, Shishi_as ** as)

Function

handle: shishi handle as allocated by shishi_init(). as: holds pointer to newly allocate Shishi_as structure. Allocate a new AS exchange variable. Returns SHISHI_OK iff successful.

void shishi_as_done (Shishi_as * as)

Function

as: structure that holds information about AS exchange Deallocate resources associated with AS exchange. This should be called by the application when it no longer need to utilize the AS exchange handle.

Shishi_asn1 shishi_as_req (Shishi_as * as)

Function

as: structure that holds information about AS exchange Returns the generated AS-REQ packet from the AS exchange, or NULL if not yet set or an error occured.

int shishi_as_req_build (Shishi_as * as)

Function

as: structure that holds information about AS exchange Possibly remove unset fields (e.g., rtime). Returns SHISHI_OK iff successful.

void shishi_as_req_set (Shishi_as * as, Shishi_asn1 asreq)

Function

as: structure that holds information about AS exchange asreq: asreq to store in AS. Set the AS-REQ in the AS exchange.

int shishi_as_req_der (Shishi_as * as, char ** out, size_t * outlen)

Function

as: structure that holds information about AS exchange out: output array with newly allocated DER encoding of AS-REQ. outlen: length of output array with DER encoding of AS-REQ. DER encode AS-REQ. out is allocated by this function, and it is the responsibility of caller to deallocate it. Returns SHISHI_OK iff successful.

int shishi_as_req_der_set (Shishi_as * as, char * der, size_t derlen)

Function

as: structure that holds information about AS exchange der: input array with DER encoded AP-REQ. derlen: length of input array with DER encoded AP-REQ. DER decode AS-REQ and set it AS exchange. If decoding fails, the AS-REQ in the AS exchange remains. Returns SHISHI_OK.

Shishi_asn1 shishi_as_rep (Shishi_as * as)

Function

as: structure that holds information about AS exchange Returns the received AS-REP packet from the AS exchange, or NULL if not yet set or an error occured.

int shishi_as_rep_process (Shishi_as * as, Shishi_key * key, const char * password)

Function

as: structure that holds information about AS exchange key: user's key, used to encrypt the encrypted part of the AS-REP. password: user's password, used if key is NULL. Process new AS-REP and set ticket. The key is used to decrypt the AP-REP. If both key and password is NULL, the user is queried for it. Returns SHISHI_OK iff successful.

int shishi_as_rep_build (Shishi_as * as, Shishi_key * key)

Function

as: structure that holds information about AS exchange key: user's key, used to encrypt the encrypted part of the AS-REP. Build AS-REP. Returns SHISHI_OK iff successful.

int shishi_as_rep_der (Shishi_as * as, char ** out, size_t * outlen)

Function

as: structure that holds information about AS exchange out: output array with newly allocated DER encoding of AS-REP. outlen: length of output array with DER encoding of AS-REP. DER encode AS-REP. out is allocated by this function, and it is the responsibility of caller to deallocate it. Returns SHISHI_OK iff successful.

void shishi_as_rep_set (Shishi_as * as, Shishi_asn1 asrep)

Function

as: structure that holds information about AS exchange asrep: asrep to store in AS. Set the AS-REP in the AS exchange.

int shishi_as_rep_der_set (Shishi_as * as, char * der, size_t derlen)

Function

as: structure that holds information about AS exchange der: input array with DER encoded AP-REP. derlen: length of input array with DER encoded AP-REP. DER decode AS-REP and set it AS exchange. If decoding fails, the AS-REP in the AS exchange remains. Returns SHISHI_OK.

Shishi_asn1 shishi_as_krberror (Shishi_as * as)

Function

as: structure that holds information about AS exchange Returns the received KRB-ERROR packet from the AS exchange, or NULL if not yet set or an error occured.

int shishi_as_krberror_der (Shishi_as * as, char ** out, size_t * outlen)

Function

as: structure that holds information about AS exchange out: output array with newly allocated DER encoding of KRB-ERROR. outlen: length of output array with DER encoding of KRB-ERROR. DER encode KRB-ERROR. out is allocated by this function, and it is the responsibility of caller to deallocate it. Returns SHISHI_OK iff successful.

void shishi_as_krberror_set (Shishi_as * as, Shishi_asn1 krberror)

Function

as: structure that holds information about AS exchange krberror: krberror to store in AS. Set the KRB-ERROR in the AS exchange.

Shishi_tkt * shishi_as_tkt (Shishi_as * as)

Function

as: structure that holds information about AS exchange Returns the newly aquired tkt from the AS exchange, or NULL if not yet set or an error occured.

void shishi_as_tkt_set (Shishi_as * as, Shishi_tkt * tkt)

Function

as: structure that holds information about AS exchange tkt: tkt to store in AS. Set the Tkt in the AS exchange.

int shishi_as_sendrecv (Shishi_as * as)

Function

as: structure that holds information about AS exchange Send AS-REQ and receive AS-REP or KRB-ERROR. This is the initial authentication, usually used to acquire a Ticket Granting Ticket. Returns SHISHI_OK iff successful.

5.8 TGS Functions

The Ticket Granting Service (TGS) is used to get subsequent tickets, authenticated by other tickets (so called ticket granting tickets). The following illustrates the TGS-REQ and TGS-REP ASN.1 structures.

-- Request --

TGS-REQ		::= KDC-REQ {12}

KDC-REQ {INTEGER:tagnum}	::= [APPLICATION tagnum] SEQUENCE {
	pvno		[1] INTEGER (5) -- first tag is [1], not [0] --,
	msg-type	[2] INTEGER (tagnum),
	padata		[3] SEQUENCE OF PA-DATA OPTIONAL,
	req-body	[4] KDC-REQ-BODY
}

KDC-REQ-BODY	::= SEQUENCE {
	kdc-options		[0] KDCOptions,
	cname			[1] PrincipalName OPTIONAL
				    -- Used only in AS-REQ --,
	realm			[2] Realm
				    -- Server's realm
				    -- Also client's in AS-REQ --,
	sname			[3] PrincipalName OPTIONAL,
	from			[4] KerberosTime OPTIONAL,
	till			[5] KerberosTime,
	rtime			[6] KerberosTime OPTIONAL,
	nonce			[7] UInt32,
	etype			[8] SEQUENCE OF Int32 -- EncryptionType
				    -- in preference order --,
	addresses		[9] HostAddresses OPTIONAL,
	enc-authorization-data	[10] EncryptedData {
					AuthorizationData,
					{ keyuse-TGSReqAuthData-sesskey
					  | keyuse-TGSReqAuthData-subkey }
				     } OPTIONAL,
	additional-tickets	[11] SEQUENCE OF Ticket OPTIONAL
}

-- Reply --

TGS-REP		::= KDC-REP {13, EncTGSRepPart,
			{ keyuse-EncTGSRepPart-sesskey
			  | keyuse-EncTGSRepPart-subkey }}

KDC-REP {INTEGER:tagnum,
	 TypeToEncrypt,
	 UInt32:KeyUsages}	::= [APPLICATION tagnum] SEQUENCE {
	pvno		[0] INTEGER (5),
	msg-type	[1] INTEGER (tagnum),
	padata		[2] SEQUENCE OF PA-DATA OPTIONAL,
	crealm		[3] Realm,
	cname		[4] PrincipalName,
	ticket		[5] Ticket,
	enc-part	[6] EncryptedData {TypeToEncrypt, KeyUsages}
}

EncTGSRepPart	::= [APPLICATION 26] EncKDCRepPart

EncKDCRepPart	::= SEQUENCE {
	key		[0] EncryptionKey,
	last-req	[1] LastReq,
	nonce		[2] UInt32,
	key-expiration	[3] KerberosTime OPTIONAL,
	flags		[4] TicketFlags,
	authtime	[5] KerberosTime,
	starttime	[6] KerberosTime OPTIONAL,
	endtime		[7] KerberosTime,
	renew-till	[8] KerberosTime OPTIONAL,
	srealm		[9] Realm,
	sname		[10] PrincipalName,
	caddr		[11] HostAddresses OPTIONAL
}

int shishi_tgs (Shishi * handle, Shishi_tgs ** tgs)

Function

handle: shishi handle as allocated by shishi_init(). tgs: holds pointer to newly allocate Shishi_tgs structure. Allocate a new TGS exchange variable. Returns SHISHI_OK iff successful.

void shishi_tgs_done (Shishi_tgs * tgs)

Function

Deallocate resources associated with AS exchange. This should be called by the application when it no longer need to utilize the AS exchange handle.

Shishi_tkt * shishi_tgs_tgtkt (Shishi_tgs * tgs)

Function

tgs: structure that holds information about TGS exchange Returns the ticket-granting-ticket used in the TGS exchange, or NULL if not yet set or an error occured.

void shishi_tgs_tgtkt_set (Shishi_tgs * tgs, Shishi_tkt * tgtkt)

Function

tgs: structure that holds information about TGS exchange tgtkt: ticket granting ticket to store in TGS. Set the Ticket in the TGS exchange.

Shishi_ap * shishi_tgs_ap (Shishi_tgs * tgs)

Function

tgs: structure that holds information about TGS exchange Returns the AP exchange (part of TGS-REQ) from the TGS exchange, or NULL if not yet set or an error occured.

Shishi_asn1 shishi_tgs_req (Shishi_tgs * tgs)

Function

tgs: structure that holds information about TGS exchange Returns the generated TGS-REQ from the TGS exchange, or NULL if not yet set or an error occured.

void shishi_tgs_req_set (Shishi_tgs * tgs, Shishi_asn1 tgsreq)

Function

tgs: structure that holds information about TGS exchange tgsreq: tgsreq to store in TGS. Set the TGS-REQ in the TGS exchange.

int shishi_tgs_req_der (Shishi_tgs * tgs, char ** out, size_t * outlen)

Function

tgs: structure that holds information about TGS exchange out: output array with newly allocated DER encoding of TGS-REQ. outlen: length of output array with DER encoding of TGS-REQ. DER encode TGS-REQ. out is allocated by this function, and it is the responsibility of caller to deallocate it. Returns SHISHI_OK iff successful.

int shishi_tgs_req_der_set (Shishi_tgs * tgs, char * der, size_t derlen)

Function

tgs: structure that holds information about TGS exchange der: input array with DER encoded AP-REQ. derlen: length of input array with DER encoded AP-REQ. DER decode TGS-REQ and set it TGS exchange. If decoding fails, the TGS-REQ in the TGS exchange remains. Returns SHISHI_OK.

int shishi_tgs_req_process (Shishi_tgs * tgs)

Function

tgs: structure that holds information about TGS exchange Process new TGS-REQ and set ticket. The key to decrypt the TGS-REQ is taken from the EncKDCReqPart of the TGS tgticket. Returns SHISHI_OK iff successful.

int shishi_tgs_req_build (Shishi_tgs * tgs)

Function

tgs: structure that holds information about TGS exchange Checksum data in authenticator and add ticket and authenticator to TGS-REQ. Returns SHISHI_OK iff successful.

Shishi_asn1 shishi_tgs_rep (Shishi_tgs * tgs)

Function

tgs: structure that holds information about TGS exchange Returns the received TGS-REP from the TGS exchange, or NULL if not yet set or an error occured.

int shishi_tgs_rep_der (Shishi_tgs * tgs, char ** out, size_t * outlen)

Function

tgs: structure that holds information about TGS exchange out: output array with newly allocated DER encoding of TGS-REP. outlen: length of output array with DER encoding of TGS-REP. DER encode TGS-REP. out is allocated by this function, and it is the responsibility of caller to deallocate it. Returns SHISHI_OK iff successful.

int shishi_tgs_rep_process (Shishi_tgs * tgs)

Function

tgs: structure that holds information about TGS exchange Process new TGS-REP and set ticket. The key to decrypt the TGS-REP is taken from the EncKDCRepPart of the TGS tgticket. Returns SHISHI_OK iff successful.

int shishi_tgs_rep_build (Shishi_tgs * tgs, int keyusage, Shishi_key * key)

Function

tgs: structure that holds information about TGS exchange keyusage: keyusage integer. key: user's key, used to encrypt the encrypted part of the TGS-REP. Build TGS-REP. Returns SHISHI_OK iff successful.

Shishi_asn1 shishi_tgs_krberror (Shishi_tgs * tgs)

Function

tgs: structure that holds information about TGS exchange Returns the received TGS-REP from the TGS exchange, or NULL if not yet set or an error occured.

int shishi_tgs_krberror_der (Shishi_tgs * tgs, char ** out, size_t * outlen)

Function

tgs: structure that holds information about TGS exchange out: output array with newly allocated DER encoding of KRB-ERROR. outlen: length of output array with DER encoding of KRB-ERROR. DER encode KRB-ERROR. out is allocated by this function, and it is the responsibility of caller to deallocate it. Returns SHISHI_OK iff successful.

void shishi_tgs_krberror_set (Shishi_tgs * tgs, Shishi_asn1 krberror)

Function

tgs: structure that holds information about TGS exchange krberror: krberror to store in TGS. Set the KRB-ERROR in the TGS exchange.

Shishi_tkt * shishi_tgs_tkt (Shishi_tgs * tgs)

Function

tgs: structure that holds information about TGS exchange Returns the newly aquired ticket from the TGS exchange, or NULL if not yet set or an error occured.

void shishi_tgs_tkt_set (Shishi_tgs * tgs, Shishi_tkt * tkt)

Function

tgs: structure that holds information about TGS exchange tkt: ticket to store in TGS. Set the Ticket in the TGS exchange.

int shishi_tgs_sendrecv (Shishi_tgs * tgs)

Function

tgs: structure that holds information about TGS exchange Send TGS-REQ and receive TGS-REP or KRB-ERROR. This is the subsequent authentication, usually used to acquire server tickets. Returns SHISHI_OK iff successful.

int shishi_tgs_set_server (Shishi_tgs * tgs, const char * server)

Function

tgs: structure that holds information about TGS exchange server: indicates the server to acquire ticket for. Set the server in the TGS-REQ. Returns SHISHI_OK iff successful.

int shishi_tgs_set_realm (Shishi_tgs * tgs, const char * realm)

Function

tgs: structure that holds information about TGS exchange realm: indicates the realm to acquire ticket for. Set the server in the TGS-REQ. Returns SHISHI_OK iff successful.

int shishi_tgs_set_realmserver (Shishi_tgs * tgs, const char * realm, const char * server)

Function

tgs: structure that holds information about TGS exchange realm: indicates the realm to acquire ticket for. server: indicates the server to acquire ticket for. Set the realm and server in the TGS-REQ. Returns SHISHI_OK iff successful.

5.9 Ticket (ASN.1) Functions

int shishi_ticket_realm_get (Shishi * handle, Shishi_asn1 ticket, char ** realm, size_t * realmlen)

Function

handle: shishi handle as allocated by shishi_init(). ticket: input variable with ticket info. realm: output array with newly allocated name of realm in ticket. realmlen: size of output array. Extract realm from ticket. Returns SHISHI_OK iff successful.

int shishi_ticket_realm_set (Shishi * handle, Shishi_asn1 ticket, const char * realm)

Function

handle: shishi handle as allocated by shishi_init(). ticket: input variable with ticket info. realm: input array with name of realm. Set the realm field in the Ticket. Returns SHISHI_OK iff successful.

int shishi_ticket_sname_set (Shishi * handle, Shishi_asn1 ticket, Shishi_name_type name_type, char * sname[])

Function

handle: shishi handle as allocated by shishi_init(). ticket: Ticket variable to set server name field in. name_type: type of principial, see Shishi_name_type, usually SHISHI_NT_UNKNOWN. Set the server name field in the Ticket. Returns SHISHI_OK iff successful.

int shishi_ticket_get_enc_part_etype (Shishi * handle, Shishi_asn1 ticket, int32_t * etype)

Function

handle: shishi handle as allocated by shishi_init(). ticket: Ticket variable to get value from. etype: output variable that holds the value. Extract Ticket.enc-part.etype. Returns SHISHI_OK iff successful.

int shishi_ticket_set_enc_part (Shishi * handle, Shishi_asn1 ticket, int etype, int kvno, char * buf, size_t buflen)

Function

handle: shishi handle as allocated by shishi_init(). ticket: Ticket to add enc-part field to. etype: encryption type used to encrypt enc-part. kvno: key version number. buf: input array with encrypted enc-part. buflen: size of input array with encrypted enc-part. Set the encrypted enc-part field in the Ticket. The encrypted data is usually created by calling shishi_encrypt() on the DER encoded enc-part. To save time, you may want to use shishi_ticket_add_enc_part() instead, which calculates the encrypted data and calls this function in one step. Returns SHISHI_OK iff successful.

int shishi_ticket_add_enc_part (Shishi * handle, Shishi_asn1 ticket, Shishi_key * key, Shishi_asn1 encticketpart)

Function

handle: shishi handle as allocated by shishi_init(). ticket: Ticket to add enc-part field to. key: key used to encrypt enc-part. encticketpart: EncTicketPart to add. Encrypts DER encoded EncTicketPart using key and stores it in the Ticket. Returns SHISHI_OK iff successful.

5.10 AS/TGS Functions

The Authentication Service (AS) is used to get an initial ticket using e.g. your password. The Ticket Granting Service (TGS) is used to get subsequent tickets using other tickets. Protocol wise the procedures are very similar, which is the reason they are described together. The following illustrates the AS-REQ, TGS-REQ and AS-REP, TGS-REP ASN.1 structures. Most of the functions use the mnemonic "KDC" instead of either AS or TGS, which means the function operates on both AS and TGS types. Only where the distinction between AS and TGS is important are the AS and TGS names used. Remember, these are low-level functions, and normal applications will likely be satisfied with the AS (see AS Functions) and TGS (see TGS Functions) interfaces, or the even more high-level Ticket Set (see Ticket Set Functions) interface.

-- Request --

AS-REQ		::= KDC-REQ {10}
TGS-REQ		::= KDC-REQ {12}

KDC-REQ {INTEGER:tagnum}	::= [APPLICATION tagnum] SEQUENCE {
	pvno		[1] INTEGER (5) -- first tag is [1], not [0] --,
	msg-type	[2] INTEGER (tagnum),
	padata		[3] SEQUENCE OF PA-DATA OPTIONAL,
	req-body	[4] KDC-REQ-BODY
}

KDC-REQ-BODY	::= SEQUENCE {
	kdc-options		[0] KDCOptions,
	cname			[1] PrincipalName OPTIONAL
				    -- Used only in AS-REQ --,
	realm			[2] Realm
				    -- Server's realm
				    -- Also client's in AS-REQ --,
	sname			[3] PrincipalName OPTIONAL,
	from			[4] KerberosTime OPTIONAL,
	till			[5] KerberosTime,
	rtime			[6] KerberosTime OPTIONAL,
	nonce			[7] UInt32,
	etype			[8] SEQUENCE OF Int32 -- EncryptionType
				    -- in preference order --,
	addresses		[9] HostAddresses OPTIONAL,
	enc-authorization-data	[10] EncryptedData {
					AuthorizationData,
					{ keyuse-TGSReqAuthData-sesskey
					  | keyuse-TGSReqAuthData-subkey }
				     } OPTIONAL,
	additional-tickets	[11] SEQUENCE OF Ticket OPTIONAL
}

-- Reply --

AS-REP		::= KDC-REP {11, EncASRepPart, {keyuse-EncASRepPart}}
TGS-REP		::= KDC-REP {13, EncTGSRepPart,
			{ keyuse-EncTGSRepPart-sesskey
			  | keyuse-EncTGSRepPart-subkey }}

KDC-REP {INTEGER:tagnum,
	 TypeToEncrypt,
	 UInt32:KeyUsages}	::= [APPLICATION tagnum] SEQUENCE {
	pvno		[0] INTEGER (5),
	msg-type	[1] INTEGER (tagnum),
	padata		[2] SEQUENCE OF PA-DATA OPTIONAL,
	crealm		[3] Realm,
	cname		[4] PrincipalName,
	ticket		[5] Ticket,
	enc-part	[6] EncryptedData {TypeToEncrypt, KeyUsages}
}

EncASRepPart	::= [APPLICATION 25] EncKDCRepPart
EncTGSRepPart	::= [APPLICATION 26] EncKDCRepPart

EncKDCRepPart	::= SEQUENCE {
	key		[0] EncryptionKey,
	last-req	[1] LastReq,
	nonce		[2] UInt32,
	key-expiration	[3] KerberosTime OPTIONAL,
	flags		[4] TicketFlags,
	authtime	[5] KerberosTime,
	starttime	[6] KerberosTime OPTIONAL,
	endtime		[7] KerberosTime,
	renew-till	[8] KerberosTime OPTIONAL,
	srealm		[9] Realm,
	sname		[10] PrincipalName,
	caddr		[11] HostAddresses OPTIONAL
}

int shishi_as_derive_salt (Shishi * handle, Shishi_asn1 asreq, Shishi_asn1 asrep, char * salt, size_t * saltlen)

Function

handle: shishi handle as allocated by shishi_init(). asreq: input AS-REQ variable. asrep: input AS-REP variable. salt: output array with salt. saltlen: on input, maximum size of output array with salt, on output, holds actual size of output array with salt. Derive the salt that should be used when deriving a key via shishi_string_to_key() for an AS exchange. Currently this searches for PA-DATA of type SHISHI_PA_PW_SALT in the AS-REP and returns it if found, otherwise the salt is derived from the client name and realm in AS-REQ. Returns SHISHI_OK iff successful.

int shishi_kdc_copy_crealm (Shishi * handle, Shishi_asn1 kdcrep, Shishi_asn1 encticketpart)

Function

handle: shishi handle as allocated by shishi_init(). kdcrep: KDC-REP to read crealm from. encticketpart: EncTicketPart to set crealm in. Set crealm in KDC-REP to value in EncTicketPart. Returns SHISHI_OK if successful.

int shishi_as_check_crealm (Shishi * handle, Shishi_asn1 asreq, Shishi_asn1 asrep)

Function

handle: shishi handle as allocated by shishi_init(). asreq: AS-REQ to compare realm field in. asrep: AS-REP to compare realm field in. Verify that AS-REQ.req-body.realm and AS-REP.crealm fields matches. This is one of the steps that has to be performed when processing a AS-REQ and AS-REP exchange, see shishi_kdc_process(). Returns SHISHI_OK if successful, SHISHI_REALM_MISMATCH if the values differ, or an error code.

int shishi_kdc_copy_cname (Shishi * handle, Shishi_asn1 kdcrep, Shishi_asn1 encticketpart)

Function

handle: shishi handle as allocated by shishi_init(). kdcrep: KDC-REQ to read cname from. encticketpart: EncTicketPart to set cname in. Set cname in KDC-REP to value in EncTicketPart. Returns SHISHI_OK if successful.