Forward-Secure Subliminal Channels based on GQ Signature

Abstract

A subliminal channel is a communication channel that enables the signer to transmit an extra secret message concealed in a digital signature to an authorized receiver. Several subliminal channels based on various digital signature schemes have been proposed. However, most proposed methods allow the subliminal receivers to obtain more information to forge a valid signature, and if the same of subliminal message are sent twice, then the outsider can distinguish subliminal channels in the signature. Moreover, once the secret key of a subliminal channel is compromised, there have no solution in current research to prevent this kind of situation reword. In this work, the subliminal channel is embedded into key-evolving base GQ signature(kebGQ) to create a subliminal forwardsecure channel. The security of the signature scheme can clearly be improved if the subliminal receivers do not share any part of the signer’s secret, and the subliminal messages can be hidden in different periods. Outsider cannot identify subliminal channels, even if the message is transmitted in twice.