This book constitutes the refereed proceedings of the Cryptographer's Track at the RSA Conference 2015, CT-RSA 2015, held in San Francisco, CA, USA, in April 2015. The 26 papers presented in this volume were carefully reviewed and selected from 111 submissions. The focus of the track is on following subjects: timing attacks, design and analysis of block ciphers, attribute and identity based encryption, membership, secure and efficient implementation of AES based Cryptosystems, chosen ciphertext attacks in theory and practice, algorithms for solving hard problems, constructions of hash functions and message authentication codes, secure multiparty computation, authenticated encryption, detecting and tracing malicious activities, implentation attacks on exponentiation algorithms and homomorphic encryption and its applications.