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Fully-phase optical image encryption in diffractive-imaging scheme with QR-code-based random illumination

Wang Z., Zhang Y., Gong Q., Li S., Qin Y.

Optica Applicata

2017

Vol. 47, nr 2

233--243

Based on a fully phase encoding and phase retrieval algorithm, a diffractive-imaging-based optical encryption scheme with random illumination is proposed. In the encryption process, a QR code image is placed in the optic path to modulate the incident light and thus generate a random illumination, which has been demonstrated to enable the proposed scheme to resist the multi-slice ptychographic phase retrieval algorithm attack. The plaintext is phase-encoded, and then encrypted by two random phase masks. The diffraction pattern in the output plane is recorded as ciphertext by a CCD camera. For decryption, an iterative phase retrieval algorithm with median filtering operation is implemented. Simulation results demonstrate the effectiveness, security, and robustness of the proposal.

Optical image encryption by using diffractive imaging with special constraint in the input plane

Wang Z., Wang H., Yang X., Zhang P., Hou C., Qin Y.

Optica Applicata

2016

Vol. 46, nr 1

57--69

In order to simplify the optical setup and the encryption process, a diffractive-imaging-based optical encryption system using a single diffraction pattern is proposed. A predesigned binary mask is placed before the plaintext in the encryption process, and three randomly distributed phase only masks are placed in the optical path. Only one diffraction pattern needs to be recorded as ciphertext by CCD. In the decryption process, an iterative phase retrieval algorithm is applied, in which the predesigned binary mask acts as a support constraint in the input plane. After the iterative process, an interpolation operation for the zero-valued pixels is also implemented. The effectiveness and robustness of the proposal are demonstrated by numerical simulation results.