Recently, Ye and Jiang (Chin Phys Lett 30(4):040305, 2013) proposed two controlled bidirectional quantum direct communication protocols by using a Green–Horne–Zeilinger state and a Bell state. This paper shows that a malicious user, Bob, can obtain the other user’s secret message without the controller’s permission by performing an intercept-and-resend attack. An improvement is then proposed to avoid this problem.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Statistical and Nonlinear Physics
- Theoretical Computer Science
- Signal Processing
- Modelling and Simulation
- Electrical and Electronic Engineering