This three-volume set LNCS 15825-15827 constitutes the proceedings of the 23rd International Conference on Applied Cryptography and Network Security, ACNS 2025, held in Munich, Germany, during June 23-26, 2025. The 55 full papers included in these proceedings were carefully reviewed and selected from 241 submissions. The papers cover all technical aspects of applied cryptography, network and computer security and privacy, representing both academic research work as well as developments in industrial and technical frontiers.