Yu-Guang Yang

Novel image encryption/decryption based on quantum Fourier transform and double phase encoding

A novel gray-level image encryption/decryption scheme is proposed, which is based on quantum Fourier transform and double random-phase encoding technique. The biggest contribution of our work lies in that it is the first time that the double random-phase encoding technique is generalized to quantum scenarios. As the encryption keys, two phase coding operations are applied in the quantum image spatial domain and the Fourier transform domain respectively. Only applying the correct keys, the original image can be retrieved successfully. Because all operations in quantum computation must be invertible, decryption is the inverse of the encryption process. A detailed theoretical analysis is given to clarify its robustness, computational complexity and advantages over its classical counterparts. It paves the way for introducing more optical information processing techniques into quantum scenarios.

Analysis and improvement of the watermark strategy for quantum images based on quantum Fourier transform

We investigate the quantum watermark strategy for quantum images based on quantum Fourier transform proposed by Zhang et al.(Quantum Inf Process 12(2):793–803, 2013). It is aimed to embed the watermark image into the Fourier coefficients of the quantum carrier image without affecting the carrier image’s visual effect. However, in our opinion the protocol is not clearly described and several steps are ambiguous. Moreover, we argue that the watermarking algorithm claimed by the authors is incorrect. At last, a possible improvement strategy is presented.

Flexible protocol for quantum private query based on B92 protocol

Jakobi et al. for the first time proposed a novel and practical quantum private query (QPQ) protocol based on SARG04 (Scarani et al. in Phys Rev Lett 92:057901, 2004) quantum key distribution protocol (Jakobi et al. in Phys Rev A 83:022301, 2011). Gao et al. generalized Jakobi et al’s protocol and proposed a flexible QPQ protocol (Gao et al. in Opt Exp 20(16):17411–17420, 2012). When

Revisiting the security of secure direct communication based on ping-pong protocol[Quantum Inf. Process. 8, 347 (2009)]

\theta <\pi /4

Comment on Efficient and feasible quantum private comparison of equality against the collective amplitude damping noise

θ<π/4, Gao et al’s protocol exhibits better database security than Jakobi et al’s protocol, but has a higher probability with which Bob can correctly guess the address of Alice’s query. In this paper, we propose a flexible B92-based QPQ protocol. Although SARG04 protocol is a modification of B92 protocol and can be seen as a generalization of B92 protocol, our protocol shows different advantages from Gao et al’s protocol. It can simultaneously obtain better database security and a lower probability with which Bob can correctly guess the address of Alice’s query when

Analysis and improvement of the dynamic watermarking scheme for quantum images using quantum wavelet transform

\theta <\pi /4