A remark on hash functions for message authentication

n A application of a special class of hash functions to cryptographic applications is considered in this paper. These hash functions arc used in cryptography to construct manipulation detection codes (MDCs), h’ h w ic arc added to messages to give some measure of assurance to the recipient that it has not been altered in transit. The basic idea is that a publicly known hash function is applied to the message to compute a hash value of fixed length. This hash value is then encrypted by the message originator and added to the message as an MDC.