This book constitutes the post-conference proceedings of the 15th International Conference on Information Security and Cryptology, Inscrypt 2019, held in Nanjing, China, in December 2019. The 23 full papers presented together with 8 short papers and 2 invited papers were carefully reviewed and selected from 94 submissions. The papers cover topics in the fields of post-quantum cryptology; AI security; systems security; side channel attacks; identity-based cryptography; signatures; cryptanalysis; authentication; and mathematical foundations.