This book constitutes the refereed proceedings of the 12th International Conference on the Theory and Application of Cryptology and Information Security, ASIACRYPT 2005, held in Shanghai, China in December 2006.The 30 revised full papers presented were carefully reviewed and selected from 314 submissions. The papers are organized in topical sections on attacks on hash functions, stream ciphers and boolean functions, biometrics and ECC computation, id-based schemes, public-key schemes, RSA and factorization, construction of hash function, protocols, block ciphers, and signatures.