From the text: This special issue of Cryptography and Communications is devoted to the international conference ALCOCRYPT 2023 (–ALgebraic and combinatorial methods for COding and CRYPTography), held in the beautiful city of Marseille, Luminy, France, from February 20–24, 2023. ALCOCRYPT was part of the thematic month “Arithmetic and Information Theory” at the famous mathematical center CIRM (“Centre International de Rencontres Mathématiques”).