News and advice from RSA Laboratories Bulletin

Recent cryptanalytic results on the properties of three popular hash functions have raised questions about their security. This note summarizes these results, gives our assessment of their implications and offers our recommendations for product planners and developers who may be using these algorithms. 1. Introduction A hash function (or more accurately a cryptographic hash function or message-digest algorithm) operates on an input string of arbitrary length and generates an output string of fixed length. This output is commonly called a hash value or a message digest. While much of the motivation for the design of a hash function comes from its usefulness in optimizing the process of digitally signing some document, hash functions can be used for a wide range of purposes.