This book constitutes the refereed proceedings of the Cryptographer's Track at the RSA Conference 2023, CT-RSA 2023, held in San Francisco, CA, USA, in April 2023. The 26 full papers presented in this volume were carefully reviewed and selected from 76 submissions. The conference presents papers on subjects such as Cryptographic Implementations, Quantum Cryptanalysis, Advanced Public-Key Encryption, Tools for Privacy-Enhancing Technologies, Symmetric Cryptanalysis, Multiparty Protocols, Digital Signatures, Fault Attacks and Side Channels, Heuristic Approaches, Symmetric-Key Constructions, and Key Agreement.

Since its introduction by Andrew Yao in the 1980s, multi-party computation has developed from a theoretical curiosity to an important tool for building large-scale privacy-preserving applications. Secure multi-party computation (MPC) enables a group to jointly perform a computation without disclosing any participant's private inputs. The participants agree on a function to compute, and then can use an MPC protocol to jointly compute the output of that function on their secret inputs without revealing them. This monograph provides an introduction to multi-party computation for practitioners interested in building privacy-preserving applications and researchers who want to work in the area. The authors introduce the foundations of MPC and describe the current state of the art. The goal is to enable readers to understand what is possible today, and what may be possible in the future. It provides a starting point for building applications using MPC and for developing MPC protocols, implementations, tools, and applications. Those seeking a concise, accessible introduction to the topic which quickly enables them to build practical systems or conduct further research will find this essential reading.