Zero-knowledge and MPC -- Efficient NIZK Arguments with Straight-Line Simulation and Extraction -- Updatable NIZKs from Non-Interactive Zaps -- Through the Looking-Glass: Benchmarking Secure Multi-Party Computation Comparisons for ReLU's -- Public-key Infrastructure -- Oh SSH-it, what's my fingerprint? A Large-Scale Analysis of SSH Host Key Fingerprint Verification Records in the DNS -- Attribute-based Anonymous Credential: Optimization for Single-Use and Multi-Use -- Auditable Asymmetric Password Authenticated Public Key Establishment -- (Augmented) Broadcast Encryption from Identity Based Encryption with Wildcard -- Attacks and Countermeasures -- Passive Triangulation Attack on ORide -- HyperDetector: Detecting, Isolating, and Mitigating Timing Attacks in Virtualized Environments -- Cryptanalysis and Provable Security -- The Construction and Application of (Related-Key) Conditional Differential Neural Distinguishers on KATAN -- How to Design Authenticated Key Exchange for Wearable Devices: Cryptanalysis of AKE for Health Monitoring and Countermeasures via Distinct SMs with Key Split and Refresh -- Cryptanalysis of the Multi-Power RSA Cryptosystem Variant -- Provable Security of HADES Structure -- Cryptographic Protocols -- Practical Single-pass Oblivious Aggregation and Billing Computation Protocols for Smart Meters -- Anonymous Random Allocation and Its Applications -- ACDC: Anonymous Crowdsourcing using Digital Cash -- Blockchain and Payment Systems -- Analyzing Price Deviations in DeFi Oracles -- Redacting Blockchain without Exposing Chameleon Hash Collisions -- Codes and Post-Quantum Cryptography -- Efficient Proofs of Retrievability using Expander Codes -- Post-Quantum Electronic Identity: Adapting OpenID Connect and OAuth 2.0 to the Post-Quantum Era.

This book constitutes the refereed proceedings of the 21st International Conference on Cryptology and Network Security, CANS 2022, which was held during November 13-16, 2022. The conference was took place in Abu Dhabi, United Arab Emirates. The 18 full and 2 short papers presented in these proceedings were carefully reviewed and selected from 54 submissions. They were organized in topical sections as follows: zero-knowledge and MPC; public-key infrastructure; attacks and countermeasures; cryptanalysis and provable security; cryptographic protocols; blockchain and payment systems; and codes and post-quantum cryptography.