Researches On Chaotic Encryption Embedded Polar Coding Scheme For Wiretap Channel

The wiretap channel model is an important security model for communication.One major concern for the wiretap channel is the secrecy capacity achieving problem under the criteria of security and reliability.In recent years,physical layer coding scheme has suc-cessively achieved the secrecy capacity of wiretap channel model by using the polar codes.However,in practical situation,physical layer polar coding scheme has failed to meet the demand of secrecy rate for the wiretap channel model in neither low secrecy capacity cases nor negative secrecy capacity cases.To solve this problem,we have presented a cross-layer scheme by combining the physical layer polar coding scheme with the upper layer chaotic stream cipher scheme.Our proposed scheme can achieve a high secrecy rate and maintain the security and reliability in both low secrecy capacity cases and negative secrecy capacity cases for the wiretap channel model.First we have introduced the basis of the polarization theory,including the channel polarization theory,encoding and decoding algorithm of the polar coding,and the source polarization theory.Specifically,we have discussed the characteristics of the channel split-ting and channel combining of channel polarization.Also we have discussed the encoding scheme of polar coding and successive cancelling decoding.And we have discussed the theory of source polarization,based on this theory,we introduced the lossless source cod-ing scheme proposed by Arikan.All these polarization theories above contribute to the construction of secure polar coding scheme under the wiretap channel model.Then we have discussed the physical layer secure polar coding scheme for the wiretap channel model.For the symmetric degraded wiretap channel model,we have discussed the secure polar coding scheme which is based on the polarized subsets division scheme,and we have proved that this secure polar coding scheme can achieve the secrecy capacity under the reliability and weak security condition.For the general wiretap channel model,we have discussed the extend solution for secure polar coding scheme,by adapting the source polarization theory and multi-block chaining structure.And we have also proved that this extended secure polar coding scheme can achieve the secrecy capacity under the reliability and strong security condition for general model.In order to construct a cross-layer cooperative scheme of physical layer secure coding scheme and up layer encryption algorithm,we choose the chaos stream cipher for encryp-tion.We have discussed the chaos stream cipher on encryption&decryption processes,security issues and the chaos system.We also have constructed a chaos stream cipher based on the binary chaos pseudo-random number generator structure(BCPRNG),and we have discussed the support vector machine structure as the binary convertor for the BCPRNG.Besides we have proved the randomness of the stream cipher generated by BCPRNG and described the specific encryption and decryption procedures.After,as the solution for low secrecy capacity cases,a cross-layer cooperative secure scheme has been constructed by combining the constructed chaos stream cipher with the se-cure polar coding scheme.Based on the practical disadvantages and limitations of physical layer coding scheme and encryption algorithm,we have proposed a cross-layer comple-mentary cooperative solution,as the chaos encrypted polar coding scheme.Our proposed scheme contains a secure key transmission scheme and a reliable ciphertext transmission scheme.Based on this scheme,we have successfully implemented the one time pad en-cryption.Also,to meet the demand of secure key space in various practical cases,we have proposed two different encrypted coding scheme.And the secrecy rate achieved by our pro-posed scheme has been proved to be higher than the secrecy capacity under the reliability and strong security condition for general wiretap channel model.Last,we have proposed another chaos encryption embedded polar coding scheme as the solution for wiretap channel model under the negative secrecy capacity cases.In our proposed scheme,based on the chaos stream cipher algorithm and secure polar coding scheme,we have constructed a chaotic frozen bites operation scheme to increase the decoding error probability for illegitimate users,to maintain a reliable and secure ciphertext transmission.Also,we have constructed a secure key chaining over the multi-block structure to guarantee the security and reliability of key transmission.And our proposed scheme has been proved to achieve a positive secrecy rate successfully under the negative secrecy capacity cases.