  Position scrambling (permutation) is widely used in multimedia encryption
schemes and some international encryption standards, such as the Data
Encryption Standard and the Advanced Encryption Standard. In this article, the
authors re-evaluate the security of a typical image-scrambling encryption
algorithm (ISEA). Using the internal correlation remaining in the cipher image,
they disclose important visual information of the corresponding plain image in
a ciphertext-only attack scenario. Furthermore, they found that the real
scrambling domain--the position-scrambling scope of ISEA's scrambled
elements--can be used to support an efficient known or chosen-plaintext attack
on it. Detailed experimental results have verified these points and demonstrate
that some advanced multimedia processing techniques can facilitate the
cryptanalysis of multimedia encryption algorithms.
