Recently an image encryption scheme based on chaotic maps and memory cellular automata has been proposed. In this paper, the security of the scheme is evaluated and it is demonstrated that the scheme can be broken by chosen plain-text attack. Having one or more monochrome plain-images and their corresponding cipher-images, a part of key-stream can be retrieved. Furthermore, it is discovered that the scheme can be broken by brute search attack with efficient time complexity, and it is also vulnerable to differential attack. Meanwhile, we provide experimental results to support the proposed attacks and suggest several improvements to make scheme stronger.
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