Provided the error rate between the keys is lower than a certain threshold (20% as of April 2007), two steps can be performed to first remove the erroneous bits and then reduce Eve's knowledge of the key to an arbitrary small value.
如果密钥之间的错误率低于某一阈值（截至2007年4月为20％），则可以执行两个步骤：首先移除错误的比特，然后将Eve对密钥的了解减少到任意小的值。