MD2 (hash function)

MD2 is a cryptographic message-digest algorithm that takes a message of any length and produces a 128-bit fingerprint, or digest, of it. Its design is described in RFC 1319, published in April 1992 by B. Kaliski of RSA Laboratories, which updated an earlier description in RFC 1115 from August 1989 and states that the description is based on material prepared by John Linn and Ron Rivest. The algorithm works on bytes in a fixed series of steps: the message is first padded with i bytes of value i until its length is a multiple of 16 bytes, a 16-byte checksum is then appended, and the padded message is processed to yield the digest. The RFC intended MD2 for digital signature applications, where a large file must be compressed in a secure manner before being signed with a private key under a public-key system such as RSA. The document is now marked Historic and was obsoleted by RFC 6149.