This book constitutes the refereed proceedings of the Third International Conference on Applied Cryptography and Network Security, ACNS 2005, held in New York, NY, USA in June 2005. The 35 revised full papers presented were carefully reviewed and selected from 158 submissions. Among the topics covered are authentication, key exchange protocols, network denial of service, digital signatures, public key cryptography, MACs, forensics, intrusion detection, secure channels, identity-based encryption, network security analysis, DES, key extraction, homomorphic encryption, and zero-knowledge arguments.