This book constitutes the refereed proceedings of the 14th International Workshop on Constructive Side-Channel Analysis and Secure Design, COSADE 2023, held in Munich, Germany, during April 3?4, 2023. The 12 full papers included in this book were carefully reviewed and selected from 28 submissions. They were organized in topical sections as follows: fault-injection analyses and countermeasures; side-channel analyses and countermeasures; attacks on PQC and countermeasure; and analyses and tools.