根据Kerckhoff准则,从选择明文攻击和选择密文攻击出发,对一种超混沌图像加密算法进行分析,结果表明该算法密钥流与明文无关,并且一个明文字节只能影响一个密文字节,导致利用选择明文攻击和选择密文攻击能够以很小的计算代价破译密文.基于此,本文提出一种改进的超混沌图像加密算法,并进行了统计分析、差分分析、相关性分析及密钥敏感性测试.理论分析及仿真结果表明,改进算法不仅可以抵御选择明文攻击和选择密文攻击,而且具有较好的统计特性及差分特性等密码学特性.%According to the Kerckhoff principle, a kind of image encryption algorithm based on hyper-chaos is discussed through choosing plaintext attack and ciphertext attack. The result shows that the key stream is independent of plaintext and one plain-text word is correlated with single cipher-text word for the algorithm, which makes the ciphertext decrypted easily with little computing by choosing plaintext and ciphertext attack. Considering the above problems, an improved algorithm based on hyper-chaos is proposed and the performance analysis is conducted, including statistical analysis, differential analysis, correlation analysis and key sensitivity testing. Theoretical analysis and simulation results show that the improved algorithm not only can resist the chosen plaintext attack and chosen ciphertext attack, but also can obtain better cryptographic properties, such as statistical characteristics, difference characteristics and so on.
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