Enhancing secure storage and sharing of multi-image in cloud environments using a novel chaotic map

To enhance the security of images during storage and transmission, a multi-image secure storage and sharing system tailored for cloud environments is proposed in this paper. The proposed system incorporates a chaos-based multi-image encryption scheme aimed at generating ciphertext images with exceptional security performance. Additionally, a revocable identity-based broadcast proxy re-encryption scheme is introduced, which offers a more efficient and secure method for storing and sharing images. A novel one-dimensional sine-coupled quadratic chaotic map is proposed, the effectiveness of which is rigorously validated through extensive chaotic tests. Within the encryption scheme, a bit-level permutation technique with innovative reconstruction rules is presented, aimed at overcoming the limitations of traditional methods and achieving more efficient permutation performance. Furthermore, the proposed disordered random diffusion method adds complexity to diffusion trajectories by employing random pulses. The chaos-based multi-image encryption scheme employs a confusion-diffusion structure. The plaintext images are first grouped for pre-encryption, followed by cross-image encryption to produce final ciphertext images. These ciphertext images are then stored with assigned a random serial number, effectively scrambling their positions. Extensive experiments are conducted to evaluate the performance. The experimental results demonstrate that the key space is 2.205×1059, correlation coefficients are close to 0, NPCR and UACI values are very close to the ideal values 99.6094% and 33.4635%, and average entropy is 7.9993. It can be demonstrated that the encryption system can withstand various malicious attacks, indicating its ability to provide high security.