This book constitutes the refereed proceedings of the 19th International Conference on Information and Communications Security, ICICS 2017, held in Beijing, China, in December 2017. The 43 revised full papers and 14 short papers presented were carefully selected from 188 submissions. The papers cover topics such as Formal Analysis and Randomness Test; Signature Scheme and Key Management; Algorithms; Applied Cryptography; Attacks and Attacks Defense; Wireless Sensor Network Security; Security Applications; Malicious Code Defense and Mobile Security; IoT Security; Healthcare and Industrial Control System Security; Privacy Protection; Engineering Issues of Crypto; Cloud and E-commerce Security; Security Protocols; Network Security.