Book excerpt: This book constitutes the refereed proceedings of the 5th International Conference on Cryptology in India, INDOCRYPT 2004, held in Chennai, India in December 2004. The 30 revised full papers presented together with 2 invited papers were carefully reviewed and selected from 181 submissions. The papers are organized in topical sections on cryptographic protocols, applications, stream ciphers, cryptographic Boolean functions, foundations, block ciphers, public key encryption, efficient representations, public key cryptanalysis, modes of operation, signatures, and traitor tracing and visual cryptography.