A Comparative Study of Image Cryptographic Method

Cryptography is a technique that is widely used to secure data transactions, this technique has also been widely used to secure digital images. There are several cryptographic techniques that are widely used in digital imagery, such as Arnold Transform, Rivest Code 4 (RC4) and One-time pad (OTP). This research aims to compare the performance of these three techniques on digital images. Performance of each encryption method is measured using entropy, SSIM, NPCR, UACI, computation time and histogram analysis. While the decrypted image is measured by the correlation coefficient and computation time using tic toc function. Based on the test results can be concluded that Arnold transforms algorithm only do a scramble on the image based on a certain iteration, so that the entropy and histogram values remain the same as the original image, only visually the image looks random and meaningless. RC4 has an advantage on entropy value and should not require a very long key, so it does not have to be a special memory to store the key. While OTP has advantages in the fastest computing time, and also superior values in NPCR, UACI, and SSIM. A random key of the same size as the original image makes encryption hard to decrypt. Although the size of the key to making the algorithm must provide a larger space for key storage.