On the Construction of Digest Functions for Manual Authentication Protocols

A digest function is a sort of universal hash that takes a key and a message as its inputs. This paper will study these functions' properties and design in the context of their application in manual authentication technology. Frequently a digest function needs to have a very short output (e.g. 16-32 bits) and no key is used to digest more than one message. These together with other characteristics represent a new kind of game played between an attacker and honest parties, which is very different from other authentication mechanisms, notably message authentication codes or MACs.