This book contains revised selected papers from the 23rd International Conference on Selected Areas in Cryptography, SAC 2016, held in St. John's, NL, Canada in August 2016.  The 28 full papers and 2 invited papers presented in this volume were carefully reviewed and selected from 100 submissions. They are organized in the following topical sections: side channels and fault attacks; design and implementation of symmetric cryptography; efficient symmetric primitives; cryptanalysis of symmetric primitives; MACs and PRNGs; lattice-based cryptography; and cryptanalysis of asymmetric primitives.