Image Blocks Encrypted then Rotated: A New Pixel-Level Scrambling Method Based Logistic Map for IOT

recently, grayscale images have been used in many areas such as healthcare or Internet Of Things (IOT), and securing these images has become important and necessary. Encryption is one of the most reliable and effective ways. Scrambling image contents adds an extra level of image security. This paper proposes a simple new method for scrambling gray images using a Chaotic Logistic Map and pixel-level rotation. In the proposed method, the gray image is encrypted first and then divided into several N×M non-overlapped blocks. The image blocks will be rotated according to the encryption key with angles of 90, 180 and 270 degrees. In the same way, the decryption process will reverse the image block’s rotation angles first, then retrieve the original image by applying the XORing operation with the same key. The efficiency of the proposed method was evaluated and analyzed by a histogram, Number of Pixel Change Rate (NPCR) and Unified Average Changing Intensity (UACI), information entropy, Peak Signal to Noise Ratio (PSNR), correlation coefficient, and Adjacent Pixels Correlation Coefficient (APCC). A comparison with other scrambling methods was carried out and the results boosted the proposed method.