This book constitutes the proceedings of the 19th IMA International Conference, IMACC 2023, held in London, UK, during December 12–14, 2023The 14 full papers included in this volume were carefully reviewed and selected from 36 submissions. This volume presents cutting-edge results in a variety of areas, including coding theory, symmetric cryptography, zeroknowledge protocols, digital signature schemes and extensions, post-quantum cryptography and cryptography in practice.