An Optimally Fair Coin Toss -- Complete Fairness in Multi-party Computation without an Honest Majority -- Fairness with an Honest Minority and a Rational Majority -- Purely Rational Secret Sharing (Extended Abstract) -- Some Recent Progress in Lattice-Based Cryptography -- Non-malleable Obfuscation -- Simulation-Based Concurrent Non-malleable Commitments and Decommitments -- Proofs of Retrievability via Hardness Amplification -- Security Amplification for Interactive Cryptographic Primitives -- Composability and On-Line Deniability of Authentication -- Authenticated Adversarial Routing -- Adaptive Zero-Knowledge Proofs and Adaptively Secure Oblivious Transfer -- On the (Im)Possibility of Key Dependent Encryption -- On the (Im)Possibility of Arthur-Merlin Witness Hiding Protocols -- Secure Computability of Functions in the IT Setting with Dishonest Majority and Applications to Long-Term Security -- Complexity of Multi-party Computation Problems: The Case of 2-Party Symmetric Secure Function Evaluation -- Realistic Failures in Secure Multi-party Computation -- Secure Arithmetic Computation with No Honest Majority -- Universally Composable Multiparty Computation with Partially Isolated Parties -- Oblivious Transfer from Weak Noisy Channels -- Composing Quantum Protocols in a Classical Environment -- LEGO for Two-Party Secure Computation -- Simple, Black-Box Constructions of Adaptively Secure Protocols -- Black-Box Constructions of Two-Party Protocols from One-Way Functions -- Chosen-Ciphertext Security via Correlated Products -- Hierarchical Identity Based Encryption with Polynomially Many Levels -- Predicate Privacy in Encryption Systems -- Simultaneous Hardcore Bits and Cryptography against Memory Attacks -- The Differential Privacy Frontier (Extended Abstract) -- How Efficient Can Memory Checking Be? -- Goldreich's One-Way Function Candidate and Myopic Backtracking Algorithms -- Secret Sharing and Non-Shannon Information Inequalities -- Weak Verifiable Random Functions -- Efficient Oblivious Pseudorandom Function with Applications to Adaptive OT and Secure Computation of Set Intersection -- Towards a Theory of Extractable Functions.

This book constitutes the refereed proceedings of the Sixth Theory of Cryptography Conference, TCC 2009, held in San Francisco, CA, USA, March 15-17, 2009. The 33 revised full papers presented together with two invited talks were carefully reviewed and selected from 109 submissions. The papers are organized in 10 sessions dealing with the paradigms, approaches and techniques used to conceptualize, define and provide solutions to natural cryptographic problems.