In order to solve the weakness of existing medial image encryption algorithm based on chaotic system in considering the image's texture feature, this paper proposed a medical image encryption and decryption method based on chaotic mapping and adaptive partitioning. Firstly, it used the 2D Sine Logistic chaotic system to generate two secure sequences with good chaotic characteristics. Then, it divided the original medical image into fixed size image blocks, and calculated their maximum pixel difference and variance. According to the given threshold, it divided these image blocks into texture smooth blocks and texture complex blocks. Finally, it used the first chaotic sequence with ciphertext feedback mechanism to encrypt the smooth blocks, and encrypt the complex blocks by using the second chaotic sequence with plaintext feedback mechanism. Therefore, it obtained the encrypted image. Because the presented algorithm efficiently considered the texture characteristics of image blocks and optimized the algorithm of chaotic encryption, it improved the encryption and decryption efficiency of medical images. Experimental simulation results show that the presented algorithm has high security and encryption efficiency. Compared with the existent method, it reduces the encryption and decryption time by about 0.5 times. The presented algorithm is suitable for real-time medical images encryption and decryption with big data size.

[2020-05-05] Printed Article /doc/2018.10.0830/v2