ccrypt  is  a  utility for encrypting and decrypting files
and streams. It was designed to replace the standard  unix
crypt  utility,  which  is notorious for using a very weak
encryption algorithm.  ccrypt is  based  on  the  Rijndael
block cipher, which was also chosen by the U.S. government
as   the   Advanced   Encryption   Standard   (AES,    see
http://www.nist.gov/aes/). This cipher is believed to pro-
vide very strong cryptographic security.

Unlike unix crypt, the algorithm provided by ccrypt is not
symmetric,  i.e.,  one  must specify whether to encrypt or
decrypt. The most common way to invoke ccrypt is  via  the
commands ccencrypt and ccdecrypt.