This book constitutes the refereed proceedings of the Third International Conference on Information and Communications Security, ICICS 2001, held in Xian, China in November 2001. The 56 revised full papers presented were carefully reviewed and selected from a total of 134 submissions. The complete spectrum of information and communications security is covered including theoretical foundations, secret sharing, network security, authentication and identification, Boolean functions and stream ciphers, security evaluation, digital signatures, block ciphers and public-key systems, information hiding, security protocols, and cryptanalysis.