可逆映射集合的图像加密算法

Invertible map set based image encryption algorithm

利用拉伸和折叠的原理,提出了一种可逆映射集合的图像加密算法。拉伸映射是将图像矩阵行、列中的像素插入到其它行、列,把图像数据矩阵拉伸为数据向量,折叠映射是按照一定顺序把向量折叠成与原图数据矩阵大小相同的加密图像数据矩阵。将拉伸映射和折叠映射互相组合构成一个可逆映射集合,密钥的每一位对应集合中的一种映射,根据密钥对图像进行循环映射以实现图像加密。推导了该算法完整的数学表达式并进行了仿真,结果表明本文所提出的加密算法具有较高的扩散效率和密钥敏感度,密钥空间大,加密速度快,能够实现图像的实时加密和解密。

Utilizing the stretch and fold mechanism,an invertible map set based image encryption algorithm is proposed.The stretch process is to insert pixels of columns or rows of an image matrix into other columns or rows to map the image matrix to an array,while the fold process is to fold the array to an encryped image matrix according to a certain sequence.The size of the encryped image matrix the same as that of the original plain-image.Several stretch and fold maps are chosen to constitute an invertible map set.Each digit of a security key denotes a corresponding map in the map set.A sequence of map iterations are done according to the order determined by the key.The encryption and decryption algorithms are formulated.The simulation results show that this proposed encryption method has high diffusivity,high sensitivity to security key,large key space and high computing speed,and capability of image encryption and decryption in real time.