Exploring Subliminal Channels in Pairing-Based Signatures

The prisoners’ problem, introduced by Simmons in 1983, describes how two individuals attempt to communicate covertly by exploiting subliminal channels without alerting a ”warden” who controls the communication. Via subliminal channels it is possible to transmit covert messages by embedding them into cryptographic digital data (traditionally by exploiting randomness that is used in probabilistic signature schemes). In this paper, we propose a formal framework to analyze the so called subliminal-freeness requirement. We explore some well known pairing-based probabilistic digital signatures and check their subliminal freeness in our proposed framework.