A Block-Permutation-Based Image Encryption Allowing Hierarchical Decryption

This paper proposes a block-permutation-based encryption (BPBE) scheme, which allows only decrypting particular regions in the encrypted image. It is difficult to perform partial decryption in the conventional scheme, because it encrypts the entire image at once. By composing regions in the original image, we can conduct the hierarchical encryption and achieve the partial decryption in the proposed scheme. Additionally, the proposed scheme can maintain the JPEG-LS compression efficiency of the encrypted images compared to the conventional scheme. Moreover, the resilience against jigsaw puzzle solving problems can be enhanced by applying the proposed scheme to the combined images. We further consider an efficient key management by using hash chains.