This book constitutes the refereed proceedings of the 15th International Conference, on Applications and Techniques in Information Security, ATIS 2025, jointly held in Melbourne, Australia; Kufa, Iraq and Abu Dhabi, UAE in December 17–20, 2025. The 10 full papers presented were carefully reviewed and selected from 149 submissions. The conference focuses on Experience Driven Cyber Advances; Quantum Computing and Advanced Applications. ATIS 2025 is supported by the Australian Government through the Council for Australia-Arab Relations.