Game-Based Criterion Partition Applied to Computational Soundness of Adaptive Security

摘要

The composition of security definitions is a subtle issue. As most security protocols use a combination of security primitives, it is important to have general results that allow to combine such definitions. We present here a general result of composition for security criteria (i.e. security requirements). This result can be applied to deduce security of a criterion from security of one of its sub-criterion and an indistinguishability criterion. To illustrate our result, we introduce joint security for asymmetric and symmetric cryptography and prove that it is equivalent to classical security assumptions for both the asymmetric and symmetric encryption schemes. Using this, we give a modular proof of computational soundness of symbolic encryption. This result holds in the case of an adaptive adversary which can use both asymmetric and symmetric encryption.