This book constitutes the refereed proceedings of the 12th International Conference on Practice and Theory in Public-Key Cryptography, PKC 2009, held in Irvine, CA, USA, in March 2009.

The 28 revised full papers presented were carefully reviewed and selected from 112 submissions. The papers are organized in topical sections on number theory, applications and protocols, multi-party protocols, identity-based encryption, signatures, encryption, new cryptosystems and optimizations, as well as group signatures and anonymous credentials.

This book constitutes the refereed proceedings of the Cryptographer's Track at the RSA Conference 2020, CT-RSA 2020, held in San Francisco, CA, USA, in February 2020. The 28 papers presented in this volume were carefully reviewed and selected from 95 submissions. CT-RSA is the track devoted to scientific papers on cryptography, public-key to symmetric-key cryptography and from crypto-graphic protocols to primitives and their implementation security.