The security conditions of one - time - used channels are given . the probabilistic detection of subliminal channels mainly under bernoulli test with binomial distribution is studied . some results of the security of many - time - used channels in hypothesis test model based on relative entropy are obtained 给出了一次使用信道的安全条件，研究了随机性的统计检测方法，主要是贝努利试验二项分布情况下的统计检测，给出了基于相对熵的假设检验模型下关于多次使用信道安全性的一些结果。
