GNU SASL Library - Libgsasl

Introduction

GNU SASL is an implementation of the Simple Authentication and Security Layer framework and a few common SASL mechanisms. SASL is used by network servers (e.g., IMAP, SMTP, XMPP) to request authentication from clients, and in clients to authenticate against servers.

GNU SASL consists of a C library (libgsasl), a command-line application (gsasl), and a manual. The library supports the ANONYMOUS, CRAM-MD5, DIGEST-MD5, EXTERNAL, GS2-KRB5, GSSAPI, LOGIN, NTLM, OPENID20, PLAIN, SCRAM-SHA-1, SCRAM-SHA-1-PLUS, SCRAM-SHA-256, SCRAM-SHA-256-PLUS, SAML20, and SECURID mechanisms.

The library is portable because it does not do network communication by itself, but rather leaves it up to the calling application. The library is flexible with regards to the authorization infrastructure used, as it utilizes callbacks into the application to decide whether an user is authorized or not.

The GNU SASL Library (lib/) is licensed under the GNU Lesser General Public License (LGPL) version 2.1 (or later). The GNU project typically uses the GNU General Public License (GPL) for libraries, and not the LGPL, but for this project we decided that we would get more help from the community if we used the LGPLv2.1+, as other free SASL implementations exists. See also Why you shouldn't use the Lesser GPL for your next library.

The command-line application and test suite (src/ and tests/) are licensed under the GNU General Public License license version 3.0 (or later). The documentation (doc/) is licensed under the GNU Free Documentation License version 1.3 (or later). See the file doc/fdl-1.3.texi.

Some of the goals with this project are:

  • Clean room implementation. This means the copyright and license conditions are clear.
  • Internationalization. It handles non-ASCII username and passwords by using SASLprep. User visible strings used in the library (error messages) can be translated into the users' language.
  • Thread safe library. This library uses no global state and multiple concurrent SASL sessions are possibly (e.g. in a multithreaded server).
  • Portable. It should work on all Unix like operating systems, including Windows. The library itself should be portable to any C89 system, not even POSIX is required.

Table of Contents

Documentation and Status

Refer to the GNU SASL Manual web page for links to the manual in all formats; however, quick links to the most popular formats:

See also the various standard texts:

GNU SASL has been ported to Windows and there are some resources around this effort:

Free software projects using GNU SASL include:

Let us know about more free software projects that use GNU SASL!

Support

A mailing list where GNU SASL users may help each other exists, and you can reach it by sending e-mail to help-gsasl@gnu.org. Archives of the mailing list discussions, and an interface to manage subscriptions, is available through the World Wide Web at https://lists.gnu.org/mailman/listinfo/help-gsasl.

Downloading

The releases are distributed from https://ftp.gnu.org/gnu/gsasl/.

The latest release is signed with OpenPGP key with fingerprint F8C4 D73C F638 C53C 06BE. Earlier releases were signed with an OpenPGP key with fingerprint B565716F or OpenPGP key with fingerprint 5A33 0664 A769 5426 5E8C.

Development

There are Savannah GNU SASL and GitLab GNU SASL project pages. You can check out the sources as follows: 

$ git clone https://gitlab.com/gsasl/gsasl.git

See the file README-hacking for complete information on how to bootstrap and build the package from version controlled sources.

We publish cyclomatic code complexity charts, self-test code coverage charts, and Clang code analysis

Dependencies

You need at least a shell, a C compiler and a Make tool to build GNU SASL.

GNU SASL will enable certain features if you have the following optional external libraries installed:

Bugs

Report all problems to help-gsasl@gnu.org, but please read the manual on how to report bugs first.

News

Note that new releases are only mentioned here if they introduce a major feature or is significant in some other way. Read the help-gsasl mailing list if you seek more frequent announcements.

Information on what is new in the software is found in the NEWS and lib/NEWS file (live version).

  • 2022年06月20日: New stable release 2.0.0 dropping all obsolete APIs.
  • 2021年01月01日: New stable release 1.10.0 with SCRAM-SHA-256 (RFC 7677).
  • 2012年05月28日: New stable release 1.8.0 with SAML20 (RFC 6595) and OPENID20 (RFC 6616).
  • 2010年12月14日: New stable release 1.6.0 with SCRAM-SHA-1(-PLUS) and GS2-KRB5 support.
  • 2010年11月14日: SCRAM-SHA-1-PLUS is supported in experimental 1.5.3 release.
  • 2010年03月31日: GS2-KRB5 is supported in the experimental 1.5.0 release.
  • 2009年11月07日: SCRAM-SHA-1 is now intended for stable use with the version 1.4 release.
  • 2009年10月08日: As of version 1.3 the library experimentally supports SCRAM-SHA-1.
  • 2008年08月19日: The library can be built as a native Windows Visual Studio project.
  • 2008年01月12日: Instructions for building GNU SASL under uClinux have been published.
  • 2007年10月08日: Git repository moved to Savannah, you can browse it.
  • 2007年07月09日: The command line, self tests, examples etc of GNU SASL are now licensed under the GPL version 3. The library remains licensed under the LGPL version 2.1.
  • 2007年06月01日: GNU SASL is now developed in git instead of cvs.
  • 2007年04月20日: Version 0.2.16, released today, will likely be the last release on the 0.2.x. branch, next we'll focus on implementing GS2.
  • 2006年06月14日: Newly released version 0.2.13 works well under Windows.
  • 2004年11月07日: A new major release, version 0.2.0, has been released.
  • 2004年04月16日: The license for the core library, and most common mechanisms, is being changed to LGPL. A release candidate of 0.0.15 with this change is available.
  • 2004年01月01日: Savannah had problems last month, and still isn't operating fully. CVS has been moved to a private machine, a read-only mirror of it will hopefully be available via Savannah in the future.
  • 2003年10月11日 Version 0.0.8 includes API for SASLprep/trace string preparation, improved portability, and more.
  • 2003年06月02日 The GSSAPI mechanism now supports GSS and Heimdal, besides MIT Kerberos.
  • 2003年03月17日 Debian includes libgsasl, thanks to Ryan M. Golbeck.
  • 2003年02月02日 The KERBEROS_V5 document is updated with examples from our library used in GNU Mailutil's imap4d server.
  • 2003年01月30日 Implementation of our KERBEROS_V5 mechanism proposal started, using Shishi.
  • 2002年12月16日 gnu.org web pages opened and development moved to savannah.
  • 2002年12月13日 Version 0.0.4 renames the package from "libgsasl" to GNU SASL and the license is changed to the GPL.
  • 2002年12月09日 Official GNU project.
  • 2002年10月07日 Initial release of version 0.0.0.