基于Spinal码的噪声式隐蔽传输

Noisy Covert Transmission Based on Spinal Code

  • 摘要: 突破传统噪声式隐蔽的局限,探索隐蔽安全与可靠性统一的传输方案设计有其重要意义及实用价值。基于Spinal码的高斯映射方式,提出一种噪声式的隐蔽传输方案,将Spinal编码输出的噪声式符号与干扰噪声间歇式交替发送,保证噪声信号的不间断,同时依托编码提升隐蔽消息的传输性能,从而实现隐蔽安全与可靠传输的统一,能较好地对抗检测攻击。Spinal码的无码率特性,哈希函数结构带来的非线性、随机性,以及编码符号的噪声式特性,保证了本方案具有信道适应性且可行性强。利用NIST进行了码的随机性测试,各项指标值均通过,表明编码符号具备随机性;结合星座图及符号的分布规律可以看出,随着参数c的增加,Spinal码的编码符号逐渐符合高斯分布;利用多阶多分辨率分析(multi-resolution analysis, MRA)方法及KL距离对信号进行分析,可以看出当参数c等于15时,无法分辨隐蔽信号与干扰噪声;结合Spinal码的误码率上界,仿真得出当码长n小于等于256时,3 dB以上就可实现10-5传输性能。上述结果综合表明,当Spinal码的编码参数c大于等于15时,本方案可实现通信传输的隐蔽安全与可靠性的统一。

     

    Abstract: ‍ ‍In order to break through the limitations of traditional noise-type covert communication, the transmission scheme with the integration of covertness, security and reliability is explored, which has great significance and practical value. Based on the Gaussian mapping method of Spinal code, a noise-type covert transmission scheme is proposed. The noise-type encoded symbols is intermittently transmitted with interference noise to ensure the uninterrupted noise signal. At the same time, the transmission performance of covert message is improved with the help of Spinal codes, where the unity of covertness, security and reliable transmission can be achieved. Furthermore, the proposed scheme can better resist detection attacks, and has channel adaptability and strong feasibility based on the rateless characteristics of Spinal code, the nonlinearity and randomness brought by hash function structure, and the noise-type characteristics of encoded symbols. At the analysis and simulation part, the encoded symbols are randomness based on NIST check with all the index values passed. As the increase of parameter c, the encoded symbols of the Spinal code gradually conform to the Gaussian distribution based on the discuss of constellation and distribution. Multi-resolution analysis (MRA) method and KL distance are used to analyze the signal. It can be seen that the covert signal and the interference noise are difficult to be distinguished when the parameter c is equal to 15. Furthermore, the upper bound of the bit error rate of the Spinal code is deduced. The simulation result shows that the transmission performance (10-5) can be achieved above 3 dB when the code length n is less than or equal to 256. Totally, it can be concluded that the unification of covertness, security and reliability of transmission can be achieved in the proposed scheme when the coding parameter c of Spinal code is greater than or equal to 15.

     

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