This book constitutes the thoroughly refereed post-proceedings of the 13th International Workshop on Fast Software Encryption, FSE 2006, held in Graz, Austria in March 2006. The 27 revised full papers presented were carefully reviewed and selected from more than 100 submissions. The papers address all current aspects of fast and secure primitives for symmetric cryptology and they are organized in topical sections on stream ciphers, block ciphers, hash functions, analysis, proposals, modes and models, as well as implementation and bounds.