A new ultrafast stream cipher design: COS ciphers

Abstract

This paper presents a new stream cipher family whose output bits are produced by blocks. We particularly focus on the member of this family producing 128-bit blocks with a 256-bit key. The design is based on a new technique called crossing over which allows to vectorize stream ciphering by using nonlinear shift registers. These algorithms offer a very high cryptographic security and much higher speed encryption than any existing stream ciphers or block ciphers, particularly the AES candidates. A 1000 euros rewarded cryptanalysis challenge is proposed.