This book constitutes the refereed proceedings of the Cryptographers' Track at the RSA Conference 2008, CT-RSA 2008, held in San Francisco, CA, USA in April 2008. The 26 revised full papers presented together with the abstract of 1 invited talk were carefully reviewed and selected from 95 submissions. The papers are organized in topical sections on hash function cryptanalysis, cryptographic building blocks, fairness in secure computation, message authentication codes, improved aes implementations, public key encryption with special properties, side channel cryptanalysis, cryptography for limited devices, invited talk, key exchange, cryptanalysis, and cryptographic protocols.