Book excerpt: This book constitutes the refereed proceedings of the Cryptographer's Track at the RSA Conference 2019, CT-RSA 2019, held in San Francisco, CA, USA, in March 2019. The 28 papers presented in this volume were carefully reviewed and selected from 75 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.