This book constitutes the refereed proceedings of the 12th International Conference on Information Systems Security, ICISS 2016, held in Jaipur, India, in December 2016. The 24 revised full papers and 8 short papers presented together with 4 invited papers were carefully reviewed and selected from 196 submissions. The papers address the following topics: attacks and mitigation; authentication; authorization and information flow control; crypto systems and protocols; network security and intrusion detection; privacy; software security; and wireless, mobile and IoT security.