Indifferentiability For Public Key Cryptosystems

We initiate the study of indifferentiability for public key encryption and other public key primitives. Our main results are definitions and constructions of public key cryptosystems that are indifferentiable from ideal cryptosystems, in the random oracle model. Cryptosystems include:Public key encryption;Digital signatures;Non-interactive key agreement.Our schemes are based on relatively standard public key assumptions. By being indifferentiable from an ideal object, our schemes automatically satisfy a wide range of security properties, including any property representable as a single-stage game, and can be composed to operate in higher-level protocols.