Encryption I -- Does Privacy Require True Randomness? -- Tackling Adaptive Corruptions in Multicast Encryption Protocols -- Universally Composable Security -- Long-Term Security and Universal Composability -- Universally Composable Security with Global Setup -- Arguments and Zero Knowledge -- Parallel Repetition of Computationally Sound Protocols Revisited -- Lower Bounds for Non-interactive Zero-Knowledge -- Perfect NIZK with Adaptive Soundness -- Notions of Security -- Security Against Covert Adversaries: Efficient Protocols for Realistic Adversaries -- On the Necessity of Rewinding in Secure Multiparty Computation -- On Expected Probabilistic Polynomial-Time Adversaries: A Suggestion for Restricted Definitions and Their Benefits -- Obfuscation -- On Best-Possible Obfuscation -- Obfuscation for Cryptographic Purposes -- Securely Obfuscating Re-encryption -- Secret Sharing and Multiparty Computation -- Weakly-Private Secret Sharing Schemes -- On Secret Sharing Schemes, Matroids and Polymatroids -- Secure Linear Algebra Using Linearly Recurrent Sequences -- Towards Optimal and Efficient Perfectly Secure Message Transmission -- Signatures and Watermarking -- Concurrently-Secure Blind Signatures Without Random Oracles or Setup Assumptions -- Designated Confirmer Signatures Revisited -- From Weak to Strong Watermarking -- Private Approximation and Black-Box Reductions -- Private Approximation of Clustering and Vertex Cover -- Robuster Combiners for Oblivious Transfer -- One-Way Permutations, Interactive Hashing and Statistically Hiding Commitments -- Towards a Separation of Semantic and CCA Security for Public Key Encryption -- Key Establishment -- Unifying Classical and Quantum Key Distillation -- Intrusion-Resilient Key Exchange in the Bounded Retrieval Model -- (Password) Authenticated Key Establishment: From 2-Party to Group -- Encryption II -- Multi-authority Attribute Based Encryption -- Conjunctive, Subset, and Range Queries on Encrypted Data -- How to Shuffle in Public -- Evaluating Branching Programs on Encrypted Data.

This book constitutes the refereed proceedings of the 4th Theory of Cryptography Conference, TCC 2007, held in Amsterdam, The Netherlands in February 2007. The 31 revised full papers presented were carefully reviewed and selected from 118 submissions. The papers are organized in topical sections on encryption, universally composable security, arguments and zero knowledge, notions of security, obfuscation, secret sharing and multiparty computation, signatures and watermarking, private approximation and black-box reductions, and key establishment.