Garbled Circuits -- LogStack: Stacked Garbling with O(b log b) Computation -- Large Scale, Actively Secure Computation from LPN and Free-XOR Garbled Circuits -- Threshold Garbled Circuits and Ad Hoc Secure Computation -- Indistinguishability Obfuscation -- Indistinguishability Obfuscation from Simple-to-State Hard Problems: New Assumptions, New Techniques, and Simplification -- Candidate Obfuscation via Oblivious LWE Sampling -- Non-Malleable Commitments -- Black-Box Non-Interactive Non-Malleable Commitments -- Non-interactive Distributional Indistinguishability (NIDI) and Non-Malleable Commitments -- Zero-Knowledge Proofs -- Public-Coin Statistical Zero-Knowledge Batch Verification against Malicious Verifiers -- Efficient Range Proofs with Transparent Setup from Bounded Integer Commitments -- Towards Accountability in CRS Generation -- Property-Preserving Hash Functions and ORAM -- Robust Property-Preserving Hash Functions for Hamming Distance and More -- Alibi: A Flaw in Cuckoo-Hashing based Hierarchical ORAM Schemes and a Solution -- Structured Encryption and Dynamic Leakage Suppression -- Blockchain -- Dynamic Ad Hoc Clock Synchronization -- TARDIS: A Foundation of Time-Lock Puzzles in UC -- Privacy and Law Enforcement -- On the power of multiple anonymous messages: Frequency Estimation and Selection in the Shuffle Model of Differential Privacy -- Non-Interactive Anonymous Router -- "Bifurcated Cryptography" Folding Competing Cryptosystems into a Single Scheme: On Accountability vs. Anonymity in Private Signatures -- Abuse Resistant Law Enforcement Access Systems. .

The 3-volume-set LNCS 12696 - 12698 constitutes the refereed proceedings of the 40th Annual International Conference on the Theory and Applications of Cryptographic Techniques, Eurocrypt 2021, which was held in Zagreb, Croatia, during October 17-21, 2021. The 78 full papers included in these proceedings were accepted from a total of 400 submissions. They were organized in topical sections as follows: Part I: Best papers; public-key cryptography; isogenies; post-quantum cryptography; lattices; homomorphic encryption; symmetric cryptanalysis; Part II: Symmetric designs; real-world cryptanalysis; implementation issues; masking and secret-sharing; leakage, faults and tampering; quantum constructions and proofs; multiparty computation; Part III: Garbled circuits; indistinguishability obfuscation; non-malleable commitments; zero-knowledge proofs; property-preserving hash functions and ORAM; blockchain; privacy and law enforcement.