Cryptology ePrint Archive: Report 2007/090

On the security of an image encryption scheme

Chengqing Li, Shujun Li, Muhammad Asim, Juana Nunez, Gonzalo Alvarez and Guanrong Chen

Abstract: This paper studies the security of a recently-proposed image encryption scheme based on chaos, and points out the following problems: 1) there exist a number of invalid keys and weak keys, and some keys are partially equivalent for the encryption/decryption processes; 2) given one chosen plain-image, a sub-key $K_{10}$ can be guessed with a smaller computational complexity than that of the simple brute-force attack; 3) given $O(10)$ (at most 128) chosen plain-images, a chosen-plaintext attack may be able to break the following part of the secret key: $(\{K_i\bmod 128\}_{i=4}^{10})$, which works very well when $K_{10}$ is not too large; 4) when $K_{10}$ is relatively small, a known-plaintext attack can be mounted with only one known plain-image to recover some visual information of other plain-images encrypted by the same key.

Category / Keywords: cryptanalysis

Date: received 8 Mar 2007, last revised 7 Aug 2007, withdrawn 10 Aug 2007

Contact author: swiftsheep at hotmail com

Available format(s): (-- withdrawn --)

Version: 20070810:142803 (All versions of this report)

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