This book constitutes the refereed proceedings of the 15th International Conference on Information Security, ISC 2015, held in Passau, Germany, in September 2012. The 23 revised full papers presented together with one invited paper were carefully reviewed and selected from 72 submissions. The papers are organized in topical sections on cryptography and cryptanalysis, mobility, cards and sensors, software security, processing encrypted data, authentication and identification, new directions in access control, GPU for security, and models for risk and revocation.