Self-Stabilizing Secure Computation

Self-stabilization refers to the ability of systems to recover after temporal violations of conditions required for their correct operation. Such violations may lead the system to an arbitrary state from which it should automatically recover. Typically, a self-stabilizing algorithm is examined for eventual functionality, namely, whether the algorithm eventually exhibit the desired input output relation. In this article, we extend the typical functionality criteria to include the recovery of privacy and security aspects. In cryptographic protocol problems, two or more parties want to perform some joint computation, while guaranteeing security properties against adversarial behavior. Current cryptographic protocols guarantee these security properties as long as the adversary is limited to compromise only a fraction of the parties. However, in reality, the adversary may compromise all the parties of the system for a while. We introduce the notion of Self-Stabilizing Secure Computation, a design that ensures that the security properties of computation are automatically regained, even if at some point the entire system is compromised. We then propose a self-stabilizing secure protocol for the evaluation of a reactive functionality which yields a computation of a virtual global finite state machine.