MoSS: Modular Security Specifications Framework

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 [10,24] (e.g., ‘ideal functionality’ in UC) or games [7,26], are monolithic, combining together different aspects of protocol requirements, environment and assumptions. Such specifications are complex, error-prone, and foil reusability, modular analysis and incremental design. We present the Modular Security Specifications (MoSS) framework, which cleanly separates each security requirement (goal) which a protocol should achieve, from the environment and model (assumptions) under which the 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 (models) or satisfying different sets of requirements. MoSS is flexible and extendable, e.g., it can support both asymptotic and concrete definitions for security. We demonstrate the applicability of MoSS to two applications: secure broadcast protocols and PKI schemes.