Encoded-image-based authentication utilizing diffractive-imaging scheme and secret-key-assisted phase retrieval

•Encoded-image authentication using diffractive-imaging and secret-key-assisted phase retrieval is proposed.•Decryption relies on phase retrieval algorithm with secret binary matrix key deduced from private aperture key.•High security achieved through expanded key space, authentication without visual exposure of secret image. Traditional optical encryption and authentication systems required complex holographic setups to capture complex-valued wavefronts. To address this limitation and create more compact architectures, there is growing interest in combining phase retrieval algorithms (PRAs) with optical authentication. However, most of the existing authentication systems based on PRAs heavily rely on random phase masks for encryption, which raises security concerns. In this paper, a secure method for encoded-image-based authentication is proposed, utilizing a diffractive-imaging scheme and secret-key-assisted phase retrieval. The method employs a simplified optical diffractive-imaging scheme to encrypt an input secret image and an aperture, resulting in the generation of a noise-like image for authentication. Both the encoded image for authentication and the aperture key are essential for decryption and authentication. The decryption process employs a secret-key-assisted phase retrieval algorithm within the framework of diffractive-imaging-based encryption. This work provides an alternative approach to authenticate users by utilizing a noise-like image and an aperture key. By providing an enlarged key space and enabling authentication without visual disclosure of the secret image, this method ensures a high level of security. Simulation results validate the feasibility and effectiveness of the proposed method.