Towards a Unified Theory of Cryptographic Agents.

Abstract

In recent years there has been a fantastic boom of increasingly sophisticated “cryptographic objects ” — identity-based encryption, fully-homomorphic encryption, functional encryption, and most recently, various forms of obfuscation. These objects often come in various flavors of security, and as these constructions have grown in number, complexity and inter-connectedness, the relationships between them have become increasingly confusing. We provide a new framework of cryptographic agents that unifies various cryptographic objects and security definitions, similar to how the Universal Composition framework unifies various multi-party computation tasks like commitment, coin-tossing and zero-knowledge proofs. Our contributions can be summarized as follows. • Our main contribution is a new model of cryptographic computation, that unifies and extends cryptographic primitives such as Obfuscation, Functional Encryption, Fully Homomorphic En-cryption, Witness encryption, Property Preserving Encryption and the like, all of which can be cleanly modeled as “schemata ” in our framework. We provide a new indistinguishability preserving (IND-PRE) definition of security that interpolates indistinguishability and simulation