Research on the Freeness of Subliminal Channels in ElGamal-Type Signatures

A new subliminal-free protocol in ElGamal-Type signatures is designed. Our design is a three-turn interactive protocol between the warden and the signer in which the warden covers all the data generated by the signer and finishes the signature, but he can not forge the signatures. It is the first time that subliminal channels exiting in random session keys in ElGamal-Type signatures are completely avoided. Our design can be viewed as a signature scheme with the warden’s examining and approving. The signer must cooperate with the warden to open the signature. Finally, a subliminal-free protocol in DSA is given.