This book constitutes the thoroughly refereed proceedings of the 9th Theory of Cryptography Conference, TCC 2012, held in Taormina, Sicily, Italy, in March 2012. The 36 revised full papers presented were carefully reviewed and selected from 131 submissions. The papers are organized in topical sections on secure computation; (blind) signatures and threshold encryption; zero-knowledge and security models; leakage-resilience; hash functions; differential privacy; pseudorandomness; dedicated encryption; security amplification; resettable and parallel zero knowledge.

In a data-driven society, individuals and companies encounter numerous situations where private information is an important resource. How can parties handle confidential data if they do not trust everyone involved? This text is the first to present a comprehensive treatment of unconditionally secure techniques for multiparty computation (MPC) and secret sharing. In a secure MPC, each party possesses some private data, while secret sharing provides a way for one party to spread information on a secret such that all parties together hold full information, yet no single party has all the...