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| -rw-r--r-- | AUTHORS | 22 | ||||
| -rw-r--r-- | README | 113 |
2 files changed, 115 insertions, 20 deletions
@@ -1,17 +1,21 @@ -The bcrypt hash module, the extended crypt_* functions, and the -high-level glue code (crypt.c, crypt-gensalt.c) come from crypt_blowfish, -originally written by Solar Designer <solar at openwall.com> and -based on algorithms and ideas by Niels Provos <provos at citi.umich.edu> -and David Mazieres <dm at lcs.mit.edu>. +The bcrypt hash module comes from crypt_blowfish, originally written +by Solar Designer <solar at openwall.com> and based on algorithms and +ideas by Niels Provos <provos at citi.umich.edu> and David Mazieres +<dm at lcs.mit.edu>. The MD5, SHA256, and SHA512 hash modules, and the underlying secure-hash primitives, were originally written by Ulrich Drepper -<drepper at cygnus.com> as part of the GNU C Library. +<drepper at cygnus.com> as part of the GNU C Library. Other people +may also have contributed to them; our records are incomplete. The DES hash module was originally FreeSec, written by David Burren <davidb at werj.com.au> for the NetBSD project, and since extensively modified by Geoffrey M. Rehmet, Mark R V Murray, and Zack Weinberg. -The work of integration into this standalone library was done by -Thorsten Kukuk <kukuk at suse.de>, Björn Esser <besser72 at fedoraproject.org>, -and Zack Weinberg <zackw at panix.com>. +The extended crypt_* interfaces also originated with crypt_blowfish, +but their implementation in this library has been totally rewritten +since then, mostly by Björn Esser and Zack Weinberg. + +The above components were assembled into this library by Thorsten Kukuk +<kukuk at suse.de>, Björn Esser <besser72 at fedoraproject.org>, and +Zack Weinberg <zackw at panix.com>. @@ -1,14 +1,105 @@ -This is the README for libxcrypt --------------------------------- +README for libxcrypt +==================== -This library is a replacement for libcrypt which comes with the -GNU C Library. It should be binary compatible with libcrypt.so.1 -in that way, as that programs linked against libcrypt.so.1 should -also work with this library, but programs linked against libxcrypt -don't need to work with libcrypt. You can replace libcrypt with a -symlink to libxcrypt. +libxcrypt is a modern library for one-way hashing of passwords. It +supports DES, MD5, SHA-2-256, SHA-2-512, and bcrypt-based password +hashes, and provides the traditional Unix 'crypt' and 'crypt_r' +interfaces, as well as a set of extended interfaces pioneered by +OpenWall Linux, 'crypt_rn', 'crypt_ra', 'crypt_gensalt', +'crypt_gensalt_rn', and 'crypt_gensalt_ra'. -The advantage of libxcrypt against libcrypt is, that it supports -blowfish password encryption. +libxcrypt is intended to be used by login(1), passwd(1), and other +similar programs; that is, to hash a small number of passwords during +an interactive authentication dialogue with a human. It is not +suitable for use in bulk password-cracking applications, or in any +other situation where speed is more important than careful handling of +sensitive data. However, it *is* intended to be fast and lightweight +enough for use in servers that must field thousands of login attempts +per minute. - Thorsten Kukuk, 21. October 2002 +Authorship and Licensing +------------------------ + +libxcrypt is currently maintained by Björn Esser and Zack Weinberg. +Many people have contributed to the code making up libxcrypt, often +under the aegis of a different project. We particularly wish to thank +Solar Designer, Ulrich Drepper, David Burren, and Thorsten Kukuk. +Please see the AUTHORS and THANKS files for a full set of credits. + +libxcrypt as a whole is licensed under the GNU Lesser General Public +License (version 2.1, or at your option, any later version). However, +many individual files may be reused under more permissive licenses if +separated from the library. Please see the LICENSING file for a +comprehensive inventory of licenses, and COPYING.LIB for the terms of +the LGPL. + +Bug Reports, Feature Requests, Contributions, Etc. +-------------------------------------------------- + +libxcrypt is currently maintained at Github: the canonical repository +URL is <https://github.com/besser82/libxcrypt>. Please file bug +reports at <https://github.com/besser82/libxcrypt/issues>. This is +also the appropriate place to suggest new features, offer patches, +etc. All your feedback is welcome and will eventually receive a +response, but this is a spare-time project for all of the present +maintainers, so please be patient. + +Portability Notes +----------------- + +libxcrypt should be buildable with any ISO C1999-compliant C compiler. +A few C2011 features are used; the intention is not to use any of them +without a fallback, but we do not currently test this. A few POSIX +and nonstandard-but-widespread Unix APIs are also used; again, the +intention is not to use any of them without a fallback, but we do not +currently test this. In particular, the crypt_gensalt functions may +not always be able to retrieve cryptographically-sound random numbers +from the operating system; if you call these functions with a null +pointer for the "rbytes" argument, be prepared for them to fail. + +Compatibility Notes +------------------- + +On Linux-based systems, by default libxcrypt will be binary backward +compatible with the libcrypt.so.1 shipped as part of the GNU C +Library. This means that all existing binary executables linked +against glibc's libcrypt should work unmodified with this library's +libcrypt.so.1. We have taken pains to provide exactly the same +"symbol versions" as were used by glibc on various CPU architectures, +and to account for the variety of ways in which the OpenWall +extensions were patched into glibc's libcrypt by some Linux +distributions. (For instance, compatibility symlinks for SuSE's +"libowcrypt" are provided.) + +However, the converse is not true: programs linked against libxcrypt +will not work with glibc's libcrypt. Also, programs that use certain +legacy APIs supplied by glibc's libcrypt ('encrypt', 'encrypt_r', +'setkey', 'setkey_r', and 'fcrypt') cannot be *compiled* against +libxcrypt. + +Binary backward compatibility can be disabled by supplying the +--disable-obsolete-api switch to 'configure', in which case libxcrypt +will install libcrypt.so.2 instead of libcrypt.so.1. This +configuration is always used on all operating systems other than +Linux. We are willing to consider adding binary backward +compatibility for other operating systems' existing libcrypts, but we +don't currently plan to do that work ourselves. + +It is also possible to remove support for DES and MD5 password hashes, +by supplying the --disable-weak-hashes switch to 'configure'. This +option implies --disable-obsolete-api. It should only be used in +contexts where there are definitely no user accounts that are old +enough to have stored their password with an old hash. + +As a final compatibility note, glibc's libcrypt could optionally be +configured to use Mozilla's NSS library's implementations of the +cryptographic primitives MD5, SHA-2-256, and SHA-2-512. This option +does not currently exist in libxcrypt, because we do not currently +believe it is a desirable option. The stated rationale for the option +in glibc is to source all cryptographic primitives from a library that +has undergone FIPS certification, but we believe FIPS certification +would need to cover all of libxcrypt itself to have any meaningful +value. Moreover, the primitive currently recommended for use by new +password hashes, bcrypt, is not available from NSS, so the +certification would not cover any part of what will hopefully be the +most used code path. |