Digital Signature with Secretly Embedded Warning
Konrad Durnoga, Jacek Pomykała, Tomasz Trabszys · Control and Cybernetics · 2013
We present a digital signature scheme with secretly embedded warning. The embedded warning is a protection mech- anism in case of restraint or blackmail. Extending ordinary digi- tal signatures we propose schemes where a signer, approached by a powerful adversary that demands handing over a signing key, can disclose his private key. In our solution the signer is able to generate a feigned key indistinguishable from the genuine one. Then such a key can be used to embed a special warning message within a sig- nature to indicate coercion. Such warnings can be transferred via subliminal channel to some trusted authority.