In this paper, an efficient chaos-based image encryption scheme is proposed, which uses the imitating jigsaw method containing revolving and shifting operations. In this scheme, there are three processes in encryption: preprocessing, encryption process, and postprocessing. In the preprocessing, the original image is partitioned into 64 × 64 pixel image blocks and then randomly revolved and shifted under control sequences which are generated by the hyperchaotic Lorenz system whose initial conditions are calculated by original image and keys. Therefore, the preprocessing is sensitive to plain image against differential attacks. In the encryption process, the after-preprocessing image is partitioned into 32 × 32 pixel image blocks; next they are randomly revolved and encrypted by control sequence and key blocks which are generated by the skew tent map. In postprocessing, the after-encryption image is partitioned into 16 × 16 pixels’ image blocks, and they are randomly revolved and shifted again under control sequences which are related with encrypted image and keys. The postprocessing further increases the diffusion characteristics. Moreover, the test experiment and security analyses are given; the results show that our proposed cryptosystem has both security and speed performance.

中文翻译：

---

一种有效的基于模拟拼图方法的基于混沌的图像加密方案

本文提出了一种有效的基于混沌的图像加密方案，该方案采用了包含旋转和平移操作的模拟拼图方法。在此方案中，加密包含三个过程：预处理，加密过程和后处理。在预处理中，将原始图像划分为64×64像素图像块，然后在超混沌Lorenz系统生成的控制序列下随机旋转和移动，该控制序列由原始图像和关键帧计算出初始条件。因此，预处理对普通图像敏感，不会受到差分攻击。在加密过程中，将预处理后的图像划分为32×32像素的图像块。接下来，它们通过偏斜帐篷图生成的控制序列和关键块被随机旋转和加密。在后处理中，将加密后的图像划分为16×16像素的图像块，并在与加密图像和密钥有关的控制序列下将它们随机旋转并再次移位。后处理进一步增加了扩散特性。给出了测试实验和安全性分析。结果表明，我们提出的密码系统具有安全性和速度性能。给出了测试实验和安全性分析；结果表明，我们提出的密码系统具有安全性和速度性能。给出了测试实验和安全性分析；结果表明，我们提出的密码系统具有安全性和速度性能。