Random-bit sequence generation from image data
The random number generated is very important in constructing encryption keys together with the other algorithm parameters. A new approach is proposed to generate a random-bit sequence with a high level of randomness. The five statistical test, Frequency, Serial, Poker, Runs and Autocorrelation are used to test the proposed algorithm, the results showed that 79% of the generated sequences can pass all of the five statistical tests together, and 94% of the generated sequences pass at least four of the statistical tests, which means the proposed algorithm can generate bit sequence with a high degree of randomness. The degree of encryption increased as the randomness level increased. Three hypotheses are suggested and tested in this paper. One of these hypotheses proved that by using CBC mode of encryption, the randomness level of the key have no significant effect on the degree of encryption. By using ECB mode, the encryption level has significant effect by using different levels of randomness key, the minimum key length gave good degree of encryption is 32 bit, which proved that the mode of image encryption determined the degree of image encryption, and some modes such as ECB of encryption depends on the level of randomness of the key, and this was proved by testing tens of images rated from simple images to complex images, such as the satellite image processed in this paper.
cbc mode ecb mode image encryption randomness bit generation