Book excerpt: This five-volume set, LNCS 14004 - 14008 constitutes the refereed proceedings of the 42nd Annual International Conference on Theory and Applications of Cryptographic Techniques, Eurocrypt 2023, which was held in Lyon, France, in April 2023. The total of 109 full papers presented were carefully selected from 415 submissions. They are organized in topical sections as follows: Theoretical Foundations; Public Key Primitives with Advanced Functionalities; Classic Public Key Cryptography; Secure and Efficient Implementation, Cryptographic Engineering, and Real-World Cryptography; Symmetric Cryptology; and finally Multi-Party Computation and Zero-Knowledge.