MCrypt, and the accompanying libmcrypt, are intended to be replacements for the old Unix crypt, except that they are under the GPL and support an ever-wider range of algorithms and modes. MCrypt has not been updated since 2007
MCrypt implements numerous cryptographic algorithms, mostly block ciphers and stream ciphers, some of which falls under export restrictions in the United States. Algorithms include des, blowfish, arcfour, enigma, ghost, LOKI97, RC2, serpent, threeway, twofish, wake, XTEA
Caution
Please note that the MCrypt library has not been updated since 2007. The PHP project has moved to deprecate and ultimately remove MCrypt from the PHP core and other projects will likely follow suit. It is highly recommended you switch to OpenSSL or another maintained encryption project.
