Chinese Physics Letters
Cryptanalysis and Improvement of Two GHZ-State-Based QSDC Protocols
Fen-Zhuo Guo, Qin Su-Juan, Wen Qiao-yan, Fu-Chen Zhu
Abstract
In a recent paper[J. Korean. Phys. Soc. 49 (2006) 459], two GHZ-state-based quantum secure direct communication protocols were presented. Here we point out that an eavesdropper can utilize a special property of GHZ states, i.e. “correlation-elicitable" to obtain half information of the transmitted secrets without being detected in both protocols. The particular attack strategy is demonstrated in detail. Furthermore, a possible improvement is proposed, which makes the protocols secure against this kind of attack.