High Efficiency of Two Efficient QSDC with Authentication Is at the Cost of 1Their Security

• 来源期刊: 中国物理快报（英文版）
• 年，卷（期）: 2009,（2）
• 页码范围: 50-52
• 页数: 3页
• 语种: 英文

摘要

Two efficient protocols of quantum secure direct communication with authentication [Chin. Phys. Lett. 25 (2008)2354] were recently proposed by Liu et al. to improve the efficiency of two protocols presented in [Phys. Rev. A 75 (2007) 026301] by four Pauli operations. We show that the high efficiency of the two protocols is at the expense of their security. The authenticator Trent can reach half the secret by a particular attack strategy in the first protocol. In the second protocol, not only Trent but also an eavesdropper outside can elicit half-information about the secret from the public declaration.