ccrypt is a Linux utility which is used for the purpose of encryption and decryption . Ccrypt was created as a replacement to UNIX's crypt utility which used a  very weak algorithm for encryption and decryptuion purposes. It is based on Rijndael cypher which is also used in the AES standard, but the difference between the two is that AES uses a 128-bit block size while ccrypt uses a 256- bit block size. The encrpyted files with ccrypt uses .cpt file extenstion.