This book contains revised selected papers from the 24th International Conference on Selected Areas in Cryptography, SAC 2017, held in Ottawa, ON, Canada in August 2017.  The 23 full papers presented in this volume were carefully reviewed and selected from 66 submissions. The focus of the conference was on specific themes in the area of cryptographic system design and analysis such as: Design and analysis of symmetric key cryptosystems Primitives for symmetric key cryptography, including block and stream ciphers, hash functions, and MAC algorithms Efficient implementations of symmetric and public key algorithms.