This book constitutes the refereed proceedings of the 8th International Workshop on Theory and Practice in Public Key Cryptography, PKC 2005, held in Les Diablerets, Switzerland in January 2005. The 28 revised full papers presented were carefully reviewed and selected from 126 submissions. The papers are organized in topical sections on cryptanalysis, key establishment, optimization, building blocks, RSA cryptography, multivariate asymmetric cryptography, signature schemes, and identity-based cryptography.