This book constitutes the thoroughly refereed post-proceedings of the 7th Annual International Workshop on Selected Areas in Cryptography, SAC 2000, held in Waterloo, Ontario, Canada, in August 2000. The 24 revised full papers presented were selected from 41 submissions and have gone through two rounds of reviewing and revision. The papers are organized in topical sections on cryptanalysis, block ciphers: new designs, elliptic curves and efficient implementations, security protocols and applications, block ciphers and hash functions, Boolean functions and stream ciphers, and public key systems.