International Association
for Cryptologic Research

Applied cryptographic protocols have to meet a rich set of security requirements under diverse environments and against diverse adversaries. However, currently used security specifications, based on either simulation (e.g., `ideal functionality' in UC) or games, are monolithic, combining together different aspects of protocol requirements, environment and assumptions. Such security specifications are complex, error-prone, and foil reusability, modular analysis and incremental design. We present the Modular Security Specifications (MoSS) framework, which cleanly separates the security requirements (goals) which a protocol should achieve, from the models (assumptions) under which each requirement should be ensured. This modularity allows us to reuse individual models and requirements across different protocols and tasks, and to compare protocols for the same task, either under different assumptions or satisfying different sets of requirements. MoSS is flexible and extendable, e.g., it can support both asymptotic and concrete definitions for security. So far, we confirmed the applicability of MoSS to two applications: secure broadcast protocols and PKI schemes.