S e c u ri ty of S t r e a m i n g M e di a Co m m u ni c a tio n s wi t h Lo gi s tic M a p a n d S elf-Ad a p tiv e D e t e c tio n-B a s e d S t e g a n o g r a p h y P e n g, J, Jia n g, Y, Tan g, S a n d M e zi a n e, F h t t p:// dx. doi.o r g/ 1 0. 1 1 0 9/TD SC. 2 0 1 9. 2 9 4 6 1 3 8Ti t l e S e c u ri ty of S t r e a mi n g M e di a Co m m u ni c a tio n s wit h Lo gis tic M a p a n d S elf-Ad a p tiv e D e t e c tio n-B a s e d S t e g a n o g r a p hy A u t h o r s P e n g, J, Jia n g, Y, Ta n g, S a n d M e zi a n e , F Typ e Articl e U RL This ve r sio n is a v ail a bl e a t : h t t p:// u sir.s alfo r d. a c. u k/id/ e p ri n t/ 5 2 6 6 0/ P u b l i s h e d D a t e 2 0 1 9 U SIR is a di git al c oll e c tio n of t h e r e s e a r c h o u t p u t of t h e U niv e r si ty of S alfo r d. W h e r e c o py ri g h t p e r mi t s, full t e x t m a t e ri al h el d in t h e r e p o si to ry is m a d e fr e ely a v ail a bl e o nli n e a n d c a n b e r e a d , d o w nlo a d e d a n d c o pi e d fo r n o nc o m m e r ci al p riv a t e s t u dy o r r e s e a r c h p u r p o s e s . Pl e a s e c h e c k t h e m a n u s c ri p t fo r a n y fu r t h e r c o py ri g h t r e s t ri c tio n s. Fo r m o r e info r m a tio n, in cl u di n g o u r p olicy a n d s u b mi s sio n p r o c e d u r e , pl e a s e c o n t a c t t h e R e p o si to ry Te a m a t: u si r@ s alfo r d. a c. u k .Abstract-Voice over IP (VoIP) is finding its way into several applications, but its security concerns still remain. This paper shows how a new self-adaptive steganographic method can ensure the security of covert VoIP communications over the Internet. In this study an Active Voice Period Detection algorithm is devised for PCM codec to detect whether a VoIP packet carries active or inactive voice data, and the data embedding location in a VoIP stream is chosen randomly according to random sequences generated from a logistic chaotic map. The initial parameters of the chaotic map and the selection of where to embed the message are negotiated between the communicating parties. Steganography experiments on active and inactive voice periods were carried out using a VoIP communications system. Performance evaluation and security analysis indicates that the proposed VoIP steganographic scheme can withstand statistical detection, and achieve secure real-time covert communications with high speech quality and negligible signal distortion.

Voice over Internet Protocol (VoIP) is widely embedded into commercial and industrial applications. VoIP streams can be used as innocuous cover objects to hide secret data in steganographic systems. The security offered by VoIP signalling protocols is likely to be compromised due to a sharp increase in computing power. This paper describes a theoretical and experimental investigation of covert steganographic communications over VoIP streaming media. A new information theoretical model of secure covert VoIP communications was constructed to depict the security scenarios in steganographic systems against passive attacks. A one way accumulation-based steganographic algorithm was devised to integrate dynamic key updating and exchange with data embedding and extraction, so as to protect steganographic systems from adversary attacks. Theoretical analysis of steganographic security using information theory proves that the proposed model for covert VoIP communications is secure against a passive adversary. The effectiveness of the steganographic algorithm for covert VoIP communications was examined by means of performance and robustness measurements. The results reveal that the algorithm has no or little impact on real-time VoIP communications in terms of imperceptibility, speech quality and signal distortion, and is more secure and effective at improving the security of covert VoIP communications than other related algorithms with comparable data embedding rates.

With an explosive growth in the deployment of networked applications over the Internet, searching the encrypted information that the user needs becomes increasingly important. However, the information search precision is quite low when using Vector space model for mass information retrieval, because long documents having poor similarity values are poorly represented in the vector space model and the order in which the terms appear in the document is lost in the vector space representation with intuitive weighting. To address the problems, this study proposed an N-level vector model (NVM)-based relevancy ranking scheme with an introduction of a new formula of the term weighting, taking into account the location of the feature term in the document to describe the content of the document properly, investigated into ways of ranking the encrypted documents using the proposed scheme, and conducted realistic simulation of information retrieval of mass encrypted data over multimedia networking. Results indicated that the timing of the index building, the most costing part of the relevancy ranking scheme, increased with the increase in both the document size and the multimedia content of the document being searched, which is in agreement with the expected. Performance evaluation demonstrated that our specially designed NVM-based encrypted information retrieval system is effective in ranking the encrypted documents transmitted over multimedia networks with large recall ratio and 1 great retrieval precision.

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The confidence level of negative survey is one of the key scientific problems. The present work uses generation function to analyse the confidence level and uses a greedy algorithm to calculate that, which is used to evaluate the dependable level of negative survey. However, the present method is of low efficiency and complex. This study focuses on an efficient approximation method for calculating the confidence level of negative survey. This approximation method based on central limit theorem and Bayesian method can get the results efficiently.