Covert Communication Based on Subliminal Channel in Broadcast Multi Signature

The subliminal channel is a covert communication channel constructed in public correspondence pattern. As a kind of the modern information hiding technology, it is used to transmit the secret information. In this paper, the subliminal channel in general ElGamal signature is analyzed. And the wideband and narrowband subliminal channel in the broadcast digital multi-signature is discussed on the presence and capacity. A scheme for closing the subliminal channel in the broadcast digital multi-signature is given, which is based on cut-and-choose method. The security and feasibility of this scheme is analyzed and discussed.