随机性检测方法在加密比特流识别中的应用研究

为识别链路层加密比特流,以未加密与加密数据在随机统计特性上的差异为依据,对4种典型的随机性检测方法在比特流长度不同时的识别率进行了比较研究.针对块内最长游程检测过程中出现的比特流尾部比特位不能构成完整子块的问题,提出了2种可行的处理方案.通过对块内最长游程检测门限值函数的研究,基于参数优化的方法改进了块内最长游程的检测方案,在一定程度上提高了识别率.最后,以某无线网络链路层加密比特流为识别对象,对提出方案的有效性进行了验证.

Research on Encrypted Bit Stream Identification by Randomness Test

To identify the encrypted bit stream of data link layer,four typical randomness tests are compared based on the differences in statistical characteristics of unencrypted and encrypted bit streams.Two possible treatments are proposed to solve the problem that the tail bits cannot constitute a complete sub-block during the test for the longest run of ones in a block.The detection scheme of the test is improved for the longest run of ones in a block based on the method of parameter optimization and the recognition rate is to a certain extent improved.Finally,the proposed scheme is verified based on the encrypted bit stream of a wireless network.