Shishi is an implementation of the Kerberos 5 network authentication system, as specified in RFC 4120. Shishi can be used to authenticate users in distributed systems. Shishi contains a library ('libshishi') that can be used by application developers to add support for Kerberos 5. Shishi contains a command line utility ('shishi') that is used by users to acquire and manage tickets (and more). The server side, a Key Distribution Center, is implemented by 'shishid'. Of course, a manual documenting usage aspects as well as the programming API is included. Shishi currently supports AS/TGS exchanges for acquiring tickets, pre-authentication, the AP exchange for performing client and server authentication, and SAFE/PRIV for integrity/privacy protected application data exchanges. Shishi is internationalized; error and status messages can be translated into the users' language; user name and passwords can be converted into any available character set (normally including ISO-8859-1 and UTF-8) and also be processed using an experimental Stringprep profile. Most, if not all, of the widely used encryption and checksum types are supported, such as 3DES, AES, ARCFOUR and HMAC-SHA1. Shishi is developed for the GNU/Linux system, but runs on over 20 platforms including most major Unix platforms and Windows, and many kind of devices including iPAQ handhelds and S/390 mainframes. Shishi is free software licensed under the GNU General Public License version 3.0 or later.