Secure multiparty computation allows two or more parties to compute a function without leaking unnecessary information about their inputs to other parties. In traditional secure multiparty computation protocols, the function is represented as a circuit and each gate of the circuit is securely computed. The mixed mode model is a generalization where only some gates are computed securely, and other gates are computed in a local, unsecured manner. There are computations where mixed mode protocols are known to be just as secure and much more efficient, and so it is natural to ask if it is possible to automatically construct optimized mixed mode secure protocols for a given function. Previous results describe powerful compilation techniques to transform circuits into efficient mixed mode protocols, but the results are only secure against very restricted (passive) adversaries. These passively secure protocols can be secured against active adversaries using extensions of classic secure multiparty computation compilation techniques. However, this comes with a significant loss of concrete efficiency, which negates the mixed mode efficiency advantages. In this thesis, we describe novel techniques that can efficiently compile mixed mode two party protocols from passive to active security. The techniques exploit structural properties of the underlying circuits to reduce the overhead of compilation without compromising the security. The gain in efficiency varies based on the circuit that is being compiled, and although for some circuits the techniques will yield no gains, for others the resulting secure protocols have exponentially lower computation and communication cost.

This book presents a holistic view on compiler assisted practical secure multi-party computation (MPC) over Boolean circuits. It discusses that two or more parties jointly evaluate a function over their inputs in such a way that each party keeps its input unknown to the other parties in MPC. MPC provides a generic way to construct Privacy-Enhancing Technologies, which protect sensitive data during processing steps in untrusted environments. A major obstacle in the past was to generate MPC applications by hand. Recently, special compilers have been developed to build all kinds of applications. This book also explains in detail how efficient MPC applications can be created automatically from ANSI-C, thus, bridging the areas of cryptography, compilation and hardware synthesis. It also gives an insight into the requirements for creating efficient applications for MPC and is hence of interest to not only researchers in the area of MPC but also developers realizing practical applications with MPC. For a better understanding of the complete compile chain from ANSI-C to circuits, which is the ‘machine code’ of MPC, the authors first give the necessary background information on MPC protocols, Boolean logic, and logic synthesis. Then the authors describe the various compilation steps required to translate any code into an adequate circuit description. Afterwards, the authors introduce a variety of optimization techniques for two classes of MPC protocols, namely techniques that improve the runtime of applications in constant- and multi-round MPC protocols. The authors also illustrate how efficient parallelization of MPC protocols can be achieved using the assistance of compilers. It presents the effectiveness of the proposed techniques by giving a detailed evaluation on benchmarking applications. Most of the aforementioned techniques are implemented in our open source compiler that is accompanying this book and allows to study compilation for MPC in practice.Researchers who are interested in practical secure multi-party computation (MPC), and developers who are interested in realizing MPC applications in practice will find this book useful as a reference, as well as advanced-level students in computer science.

Practitioners and researchers seeking a concise, accessible introduction to secure multi-party computation which quickly enables them to build practical systems or conduct further research will find this essential reading.

Secure Multi-Party Computation MPC is one of the most powerful tools developed by modern cryptography it facilitates collaboration among mutually distrusting parties by implementing a virtual trusted party. Despite the remarkable potential of such a tool, and decades of active research in the theoretical cryptography community, it remains a relatively inaccessible and lesser-known concept outside of this field. Only a handful of resources are available to students and researchers wishing to learn more about MPC. The editors of this book have assembled a comprehensive body of basic and advanced material on MPC, authored by

We generate and gather a lot of data about ourselves and others, some of it highly confidential. The collection, storage and use of this data is strictly regulated by laws, but restricting the use of data often limits the benefits which could be obtained from its analysis. Secure multi-party computation (SMC), a cryptographic technology, makes it possible to execute specific programs on confidential data while ensuring that no other sensitive information from the data is leaked. SMC has been the subject of academic study for more than 30 years, but first attempts to use it for actual computations in the early 2000s – although theoretically efficient – were initially not practicable. However, improvements in the situation have made possible the secure solving of even relatively large computational tasks. This book describes how many different computational tasks can be solved securely, yet efficiently. It describes how protocols can be combined to larger applications, and how the security-efficiency trade-offs of different components of an SMC application should be chosen. Many of the results described in this book were achieved as part of the project Usable and Efficient Secure Multi-party Computation (UaESMC), which was funded by the European Commission. The book will be of interest to all those whose work involves the secure analysis of confidential data.

The three volume-set LNCS 12105, 12106, and 12107 constitute the thoroughly refereed proceedings of the 39th Annual International Conference on the Theory and Applications of Cryptographic Techniques, EUROCRYPT 2020, which was due to be held in Zagreb, Croatia, in May 2020. The conference was held virtually due to the COVID-19 pandemic. The 81 full papers presented were carefully reviewed and selected from 375 submissions. The papers are organized into the following topical sections: invited talk; best paper awards; obfuscation and functional encryption; symmetric cryptanalysis; randomness extraction; symmetric cryptography I; secret sharing; fault-attack security; succinct proofs; generic models; secure computation I; quantum I; foundations; isogeny-based cryptography; lattice-based cryptography; symmetric cryptography II; secure computation II; asymmetric cryptanalysis; verifiable delay functions; signatures; attribute-based encryption; side-channel security; non-interactive zero-knowledge; public-key encryption; zero-knowledge; quantum II.

The Model Rules of Professional Conduct provides an up-to-date resource for information on legal ethics. Federal, state and local courts in all jurisdictions look to the Rules for guidance in solving lawyer malpractice cases, disciplinary actions, disqualification issues, sanctions questions and much more. In this volume, black-letter Rules of Professional Conduct are followed by numbered Comments that explain each Rule's purpose and provide suggestions for its practical application. The Rules will help you identify proper conduct in a variety of given situations, review those instances where discretionary action is possible, and define the nature of the relationship between you and your clients, colleagues and the courts.