Mcrypt is a crypting program, intended to be replacement for the old unix crypt(1). But it can do a lot more, since with its libmcrypt library it can encrypt and decrypt with the following algorithms: BLOWFISH, TWOFISH, DES, TripleDES, 3-WAY, SAFER-sk64, SAFER-sk128, SAFER+, OKI97, GOST, RC2, RC6, MARS, IDEA, RIJNDAEL-128, RIJNDAEL-192, SERPENT, RIJNDAEL-256, CAST-128 (known as CAST5), CAST-256, ARCFOUR, ENIGMA, PANAMA, XTEA and WAKE.
Please note that this package is buggy and unmaintained by the upstream authors. If you can, please look for other implementations (openssl, gnutls, gnupg).