Subliminal Channel In Multisignature

The subliminal channel is a covert communication channel constructed in public correspondence pattern. As one kind of the modern information hiding technology, it is used to transmit the secret information. It is a covert communication channel to send a message to an authorized receiver. This channel is constructed in the output crypto-data of an applied public-key cryptosystem such as digital signature, authentication, and so on. The message can not be discovered by any unauthorized receivers. The message transmitted in subliminal channel is known as subliminal message. Multi-signature, as an important part of digital signature, mainly referring to multiple users need to sign on a document at the same time. It can be mainly divided into sequential multi-signatures and broadcasting multi-signatures.The research on the subliminal channel in Multi-signature is of great significance. On one hand, it can provide a method to transform the information, on the other hand, we can close the subliminal channel, to prevent network attacks engaging in illegal activitiesThe main contents and research attributions of this dissertation are as follows:1. This dissertation analyses the subliminal channel in ordinal multi signature. A scheme of ordinal multi signature is given, and the subliminal channel in the scheme is analyzed and tested in software. The time cost increases with the channel capacity, so we can select the appropriate channel capacity to meet the real-time requirements.2. For broadcasting multi-signatures, a scheme of broadcasting multi-signatures is given and the subliminal channel is analyzed. The conclusion is that, in this scheme, the broad-band subliminal channel can't be constructed, and the narrow band subliminal channel can be constructed between every member.3. Further more, the subliminal channel in multi-signature based on elliptic curve cryptography system is given and analyzed. The conclusion is that the broad-band subliminal channel is closed, and in the narrow band subliminal channel, a t-bits message need to chooses"k"for 2t times. 4. In this dissertation, deferent methods of closing subliminal channels in Multi-Signature are given, and a communication system based on subliminal channels is constructed, the safety and real-time of the system is tested, and all the algorithms can be done in a short time.