密钥生成系统中的双门限量化算法研究

针对密钥生成系统中传统量化算法导致合法双方初始不一致率较高从而降低最终的密钥生成长度的问题，提出了双门限量化的基本模型，合法双方同时设置一个上门限和下门限，将高于上门限的采样值量化为1，低于下门限的采样值量化为0，同时将上、下门限之间的采样值舍弃。通过分析可知，这种量化方法有较高的可靠性，并且不会泄露有关密钥的任何信息。本文分析了其在密钥生成中的具体应用，并以合法双方最终生成的密钥的长度为目标函数，推导得到了双门限量化时最优的量化因子。进一步的仿真表明，相比较传统的等概量化，通过选择合适的量化因子，合法双方能够生成更长的密钥。在信噪比为15 dB-25 dB时，密钥长度的提升在0.1比特以上。 

The Research of Double-threshold Quantization Algorithm in the Secret Key Generation System

The traditional quantization methods lead high initial disagreement rate in the secret key generation courses, which would reduce the final length of secret key. The basic model of double-threshold quantization was proposed. The legitimate users set a high threshold and a low threshold at the same time. The sampled values are quantized to 1 when the values are greater than the high threshold and to 0 when the values are lower than the low threshold; the values between the two thresholds are not encoded. Through analysis, we can find that this method allows high reliability and does not reveal anything about the generated bits to the wiretapper. Its application in the secret key generation system was also analyzed in this paper, by taking the final secret key length generated by legitimate users as target function, the optimized quantization factors were deduced. The farther simulation results show that the legitimate users can generate more secret key bits by selecting appropriate quantization factors. The length of secret key is increased by 0.1 bits above when the signal to noise is between 15dB to 25dB.