This book constitutes the proceedings of the 19th International Conference on Smart Card Research and Advanced Applications, CARDIS 2020, which took place during November 18-20, 2020. The conference was originally planned to take place in Lübeck, Germany, and changed to an online format due to the COVID-19 pandemic. The 12 full papers presented in this volume were carefully reviewed and selected from 26 submissions. They were organized in topical sections named: post-quantum cryptography; efficient implementations; and physical attacks.