Provably Secure Double Block Length Hash Functions with Rate 1/2

摘要

There has been no known construction of an double-block-length hash function which is optimally collision resistant, that is, the time complexity of any collision-finding algorithm for it is Ω(2{sup}(l/2)), where l is the output length. In this article, double-block-length hash functions with rate (less than) 1/2 are presented which are optimally collision resistant in a black-box model.