Digital Image Cryptography using Lookup Table

Abstract

Protecting digital images is an important task, because images may be secret or may be contain valuable secret information. In this paper research a simple, efficient and high secure method of digital images protection will be introduced. The method will use a chaotic logistic map model with a selected chaotic parameter to generate a lookup table, which will be used in the encryption and decryption phases. The proposed method can use one lookup table to encrypt-decrypt color images, or it can use three lookup tables to encrypt-decrypt each color channel. The method will secure the encrypted image by using a complicated private key, which will provide a suitable key space capable to resist hacking attacks, the method outputs will be very sensitive to the selected private key contents, any minor changes in these contents in the decryption phase will be considered as a hacking attempt by producing a damaged decrypted image. It will be shown how using lookup table simplifies the process of image cryptography using the indexes and the indexes contents of the lookup table. The proposed method will be implemented and the obtained results will be analyzed to prove the quality of encryption and decryption phases based on the calculated MSE, PSNR, CC and NSCR. The speed of the proposed method will be tested, to show how the proposed method will increase the throughput of data cryptography by decreasing both the encryption and decryption times.