The md5 was designed by professor Ronald l. Rivest of MIT in 1991. The md5 message-digest algorithm is the most widely used cryptographic hash function producing a 128-bit (16-byte) hash value, typically expressed in text format as a 32 digit hexadecimal number. It was developed to be used with digital signature applications that require large files to be compressed by a secure method before being encrypted with a secret key, under a public key cryptosystem. Md5 is currently a standard internet engineering task force (ietf) request for comments (rfc) 1321.