Research On Hash Function-Based Subliminal Channel Technique

Subliminal channel is a channel which is built in the public channel in order to realize secret communication. In addition to the authorized receiver, any other can not discover the secret message. It is a typical modern information hiding technology and has enormous military value, commercial value and social value. Information security industry has carried out in-depth study in the establishment and the closing of the subliminal channel, which are conflicting and mutual restraint. The subliminal channels exists in the most of the signature system, it presents a deeper challenge to information security, so it has become an urgent problem to be solved for security mechanisms to effectively close the subliminal channels.This paper research the free protocol of the subliminal channels. First, this paper reviews the developments of the subliminal channel technology, and then summarizes some needed theoretical knowledge. At last, it focuses on analyzing the closing of the subliminal channels; it respectively proposes a subliminal-free protocol of two different types of signature schemes, preventing network attacks engaging in illegal activities.The main contributions of the dissertation are listed as follows.(1) In the ELGamal-Type broadcast multi-signature, the random parameters can introduce the subliminal channels and cause potential safety problems. Aiming at this problem, a new interactive subliminal-free protocol is designed. Thereinto, the warden cooperates with each signer for generating part signature, signature center generates multi-signature. The existence of collision-free hash functions ensure that the warden can not forge the signatures, so the signature authority of the signer is guaranteed. Compared with similar agreement, theoretical analysis shows that the proposed protocol is not only closing the subliminal channel but also lower in computation complexity and higher in communications efficiency.(2) The wideband and narrowband subliminal in Schnorr Designated-Recipient Signature are discussed. A new interactive subliminal-free protocol is designed. In the scheme, warden can not forge the signatures, so the signature authority of the signer is guaranteed. The security of the proposed protocol is based on both the discrete logarithm intractability assumption and the existence of collision-free hash functions. It is certified that the subliminal channels exiting in the random parameters in the Schnorr Designated-Recipient Signature are avoided. Finally, it analyses the computational efficiency of the new protocol.