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Studies On Information Hiding And Subliminal Channels

Posted on:2002-09-14Degree:DoctorType:Dissertation
Country:ChinaCandidate:T ZhangFull Text:PDF
GTID:1118360062475200Subject:Cryptography
Abstract/Summary:PDF Full Text Request
Information hiding is a new technology combined with theory and technology ofmany other subjects. It is a branch of information security closely connected withcryptology. Digital media are used as the covers in information hiding. The secretmessage is hidden in the cover. It conceals the existence of the secret message. In thisthesis, the theory and the applications of a typical information technology, subliminalchannel, are studied and introduced.Subliminal channel was initially studied concerning with the problems ofnon-definite public key digital signature. It focused on the existing proof of subliminalchannel and its bandwidth. The presence of Newton channel is the typical achievement.It solved the problem of compromise between the security of a digital signature and thebandwidth of the subliminal channel. But there are some inherent defects of theNewton channel that make the subliminal recipient have the ability to forge the digitalsignatures. The use of subliminal channel and the close of subliminal channel are bothconflicting and stimulating with each other. There are serious defects in some schemesof close subliminal channel proposed early times.Information theoretic analyses are made for the security condition of variessubliminal channels. The relationship between the subliminal message and security ofthe public key cryptography algorithm is given. An information-theoretic model for thesubliminal channel is proposed based on the hypothesis testing method of statisticaldeduction and the relative entropy. The definition of the security of the subliminalchannel is given, and the security formula is deduced.Following are the main results of this thesis:1.In the research aspect of the bandwidth of the subliminal channel, thedefects of the Newton channel are analyzed. A scheme which thesubliminal recipient having the ability to forge the digital signatures isdevised. And the Newton channel is improved in this thesis.2.The analysis of the cut-and-choose method failure in closing thesubliminal channel is given. And the subliminal channels based on thecut-and-choose method are discussed. The formulae of the theoreticalbandwidth and that of the practicable bandwidth for computation arededuced.3.Two schemes based on the zero-knowledge proof protocol and thedivertible protocol are proposed, which can close the known subliminalchannels successfully.4.The relationship between the subliminal message and security of thepublic key cryptography algorithm is given according to the informationtheory. To improve the transmission efficiency of the subliminal message,the supraliminal channel is utilized to transmit public keys. Then theman-in-the-middle attack can be avoided.5.An information-theoretic model for the subliminal channel is proposedbased on the hypothesis testing method and the relative entropy. Theconcept of the security of the subliminal channel is given, and the securityformula is deduced. There is a bound of the probability, which is not equalto zero, of the use of the subliminal channel not being discovered, i.e., theuse of the subliminal channel is not always unconditionally secure.
Keywords/Search Tags:information hiding, subliminal channel, Newton channel, zero-knowledge proof, information-theoretical security
PDF Full Text Request
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