DWTAT-DASIS: Fusion of discrete wavelet transform and access tree for distributed authentication in secret image sharing

Secret sharing of distributed data in cloud environments prevents unauthorized and wanton access and misuse by malicious participants. However, when applying secret sharing to image formats, the fixed range of pixel values in images presents unique challenges for share recovery, often resulting in recovery algorithms that reconstruct images in a lossy manner. Moreover, one-way authentication methods for participants in cloud environments are insufficient to address the heightened security demands of high-trust scenarios. This paper presents a secret image-sharing scheme with distributed authentication (DWTAT-DASIS) designed for cloud storage environments. By leveraging Discrete Wavelet Transform and an Access Tree structure, the scheme addresses the limitations of existing approaches (such as compression-based secret sharing and visual cryptography), which fail to provide lossless image recovery and efficient performance. Additionally, DWTAT-DASIS enhances security through fine-grained access control and two-way authentication. Finally, security analysis and experiments were conducted on the proposed protocol, demonstrating its ability to resist common attack methods as well as some deeper-level attack methods, meeting the security requirements for image storage in cloud systems. Experimental analysis shows that compared with similar protocols, this protocol can ensure the integrity of image restoration and greatly reduce the probability of image transmission being attacked.