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 information. The authors present basic feasibility results from the last 30 years, generalizations to arbitrary access structures using linear secret sharing, some recent techniques for efficiency improvements, and a general treatment of the theory of secret sharing, focusing on asymptotic results with interesting applications related to MPC.

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.

This book constitutes the refereed proceedings of the 11th International Workshop on Practice and Theory in Public-Key Cryptography, PKC 2008, held in Barcelona, Spain, in March 2008.

The 21 revised full papers presented together with 1 invited lecture were carefully reviewed and selected from 71 submissions. The papers are organized in topical sections on algebraic and number theoretical cryptoanalysis, theory of public key encryption, digital signatures, identification, broadcast and key agreement, implementation of fast arithmetic, and public key encryption.

These are the proceedings of the 24th Annual IACR Eurocrypt Conference. The conference was sponsored by the International Association for Cryptologic Research(IACR;seewww.iacr.org), thisyearincooperationwiththeComputer Science Department of the University of Aarhus, Denmark. As General Chair, Ivan Damg? ard was responsible for local organization. TheEurocrypt2005ProgramCommittee(PC)consistedof30internationally renowned experts. Their names and a?liations are listed on pages VII and VIII of these proceedings. By the November 15, 2004 submission deadline the PC had received a total of 190 submissions via the IACR Electronic Submission Server. The subsequent selection process was divided into two phases, as usual. In the review phase each submission was carefully scrutinized by at least three independent reviewers, and the review reports, often extensive, were committed to the IACR Web Review System. These were taken as the starting point for the PC-wideWeb-baseddiscussionphase.Duringthisphase, additionalreportswere provided as needed, and the PC eventually had some 700 reports at its disposal. In addition, the discussions generated more than 850 messages, all posted in the system. During the entire PC phase, which started in August 2003 with my earliest invitations to PC members and which continued until March 2005, more than 1000 email messages were communicated. Moreover, the PC received much appreciated assistance from a large body of external reviewers. Their names are listed on page VIII of these proceeding

The aim of this text is to treat selected topics of the subject of contemporary cryptology, structured in five quite independent but related themes:
- efficient distributed computation modulo a shared secret
- multiparty computation
- foundations of modern cryptography
- provable security for public key schemes
- efficient and secure public-key cryptosystems.