This book constitutes the refereed proceedings of the Cryptographers' Track at the RSA Conference 2013, CT-RSA 2013, held in San Francisco, CA, USA, in February/March 2013. The 25 revised full papers presented were carefully reviewed and selected from 89 submissions. The papers are grouped into topical sections covering: side channel attacks, digital signatures, public-key encryption, cryptographic protocols, secure implementation methods, symmetric key primitives, and identity-based encryption.