研究了有偏振漂移的量子保密系统中的截听重发攻击问题。利用二维模型刻画密钥分发的过程。通过模型分析和研究计算，得到了合法通信者以及窃听者之间的关系式， 掌握了系统的探测效率损耗，以及量子误码率的波动范围。筛后数据的互信息量显示，相比BB84协议，B92协议的互信息量低，这是由于B92协议将协议所用的 量子态简化为两态所付出的代价。窃听者获取的信息可能多于合法通信者得到的信息，这也将威胁密钥产生的保密性。

The intercept-resent eavesdropping was explored in the polarization-drift quantum cryptography. Two-dimension model was used to describe the key distribution process. Model analysis and calculation provide precise relation between legitimate communicators and eavesdroppers. The loss of detection efficiency and fluctuation of QBER were obtained. The mutual information in the sifted keys shows that, comparing to BB84 protocol, the mutual information in B92 protocol is lower, which is caused by the simplified states from four states to two states. The information obtained by an eavesdropper can be more than that in the legitimate partners, which will threaten the privacy of the keys generated.