Cryptosystem is a cryptographic system, that is science and art to maintain the safety of messages by encrypting it into a form that cannot be understood what the meaning is. Message safety includes confidentiality / privacy, authenticity / integrity, authentication and non repudiation. One of the cryptographic algorithms is Mc Ellice algorithm. Mc Ellice algorithm is based on matrix computation, so it has safety on the keys that are not easily solved. The result of this cryptosystem is a message in the form of a password / encryption, i.e. chipper text which is ready to be transmitted, for example, by means of e-mail. After that, the message receiver will describe that chip text and get the actual message content / plaintext.Key words : Cryptosystem, cryptography, chipper text, plaintext, public key, private key, encryption, description
