The security of the scheme for QC is a crucial problem. In the classical communication, the eavesdropper (traditionally called Eve) can get the information about the key shared by Alice and Bob, so does she in the QC.

• 量子密钥的安全性问题主要是考虑窃听者(通常称之为Eve)，采取何种窃听方案，能够窃听到多少信息量以及合法的通信双方(通常称之为Alice和Bob)如何判断所建立的密钥是安全的问题。