International Association for Cryptologic Research

International Association
for Cryptologic Research


Paper: A General Cryptanalysis of Permutation-Only Multimedia Encryption Algorithms

Shujun Li
Chengqing Li
Guanrong Chen
Nikolaos G. Bourbakis
Kwok-Tung Lo
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Abstract: In recent years secret permutations have been widely used for protecting different types of multimedia data, including speech files, digital images and videos. Based on a normalized encryption/decryption model, this paper performs a quantitative cryptanalysis on the security of permutation-only image ciphers working in the spatial domain, taking a recently-proposed permutation-only image cipher called HCIE (hierarchical chaotic image encryption) as a typical example. When the plain-image is of size $M\times N$ and with $L$ different levels of pixel values, the following quantitative cryptanalytic findings have been concluded: 1) all permutation-only image ciphers are insecure against known/chosen-plaintext attacks in the sense that only $O\left(\log_L(MN)\right)$ known/chosen plain-images are enough to break the secret permutation mapping; 2) the computational complexity of the known/chosen-plaintext attack is only $O(n\cdot(MN)^2)$, where $n$ is the number of known/chosen plain-images involved. Based on these results, it is found that hierarchical permutation-only image ciphers such as HCIE are less secure than normal (i.e., non-hierarchical) permutation-only image ciphers. Experiments are shown to verify the feasibility of the known/chosen-plaintext attacks. The cryptanalysis result is then generalized to permutation-only image ciphers working in the frequency domain, as well as video ciphers and speech ciphers. Finally, it is suggested that secret permutations have to be combined with other encryption techniques to design highly secure multimedia encryption systems. To the best of our knowledge, for the first time this paper provides a quantitative analysis of such a security principle on the design of multimedia encryption algorithms, from both theoretical and experimental points of view.
  title={A General Cryptanalysis of Permutation-Only Multimedia Encryption Algorithms},
  booktitle={IACR Eprint archive},
  keywords={applications / cryptanalysis, secret permutation, multimedia encryption},
  note={ 13630 received 29 Dec 2004, last revised 27 Apr 2007},
  author={Shujun Li and Chengqing Li and Guanrong Chen and Nikolaos G. Bourbakis and Kwok-Tung Lo},