为生成真随机数序列, 提出了先将大气湍流传输中激光散斑图像作为随机数发生器的熵源, 再采用变帧频采样方法进行提取随机数的算法。首先, 为降低相邻激光散斑图像间高相关性对随机性的影响, 提出了变帧频采样方法。其次, 对实验数据进行处理, 根据大气湍流造成激光光斑质心的随机抖动特征, 对散斑图像划分灰度等级, 编码和后处理等操作, 从而提取随机数。最后, 利用NIST测试工具对提取的随机序列进行实验分析, 结果表明: 该序列不仅达到真随机数的标准, 而且序列的数量和随机性均高于等帧频采样方法生成的随机序列。此外, 对激光散斑视频归一化方差与最优采样区间之间的关系进行分析, 为进一步的研究提供重要依据。

In order to generate true random sequences, a random number extraction algorithm with variable frame rate was proposed by using laser speckle video of atmospheric turbulence as entropy source of random number generator. Firstly, an image sampling method with variable frame rate was proposed to reduce the effect on randomness of high correlation between adjacent laser speckle images. Secondly, random numbers were extracted by processing the experimental data according to the random jitter characteristics of the centroid of laser spot caused by atmospheric turbulence, dividing the speckle images into different gray levels, and executing encoding and post-processing operations. Finally, experimental analysis for the extracted random sequence was carried out by the NIST test tools. Result shows that this sequence not only reachs the standard of true random numbers, its amount and randomness are also higher than those of the random sequence generated by the equal frame rate sampling method. In addition, the relationship between the normalized variance of laser speckle video and the optimal sampling interval was analyzed, which provided an important basis for further research.