Research On Chaos Based Digital Image Encryption Algorithm

We analysed the definition, randomness, sensibility, and cyclicity of logistic map. Then a novel image cryption agrithm based on the improved logistic map was proposed. The experimental results show that the algorithm has good characteristics shuch as well randomness, consistent distributing. The algorithm can resist known-plaintext attacks and chosen-plaintext attacks.Because the security of most conventional chaos based encryption algorithms are low, to solve thess problems, we proposed a novel image cryption agrithm based on two chaotic sequences sort. The encryption algorithm uses both the improved logistic maps and the sin maps. based on the two chaotic sequences sort transformation, the algorithm obtains the address codes of the images transposition by the sort transformation of the two chaotic sequences. The experimental results show that the algorithm has nice scrambling capability and guarantees the security of the encrypted images effectively. It improved the complexity of the encryption system and made the system more difficult to break.According to the characteristic of higher secrecy of high-dimension chaotic system, a new colour image encryption algorithm based on unified chaotic system and general cat maps was proposed. Firstly, tricolor scrambling transformation is realized in space domain by using the general cat maps, respectively. Then the three chaotic sequences of unified chaotic system were adopted to realize the tricolor substitution transformation pixel by pixel. The results demonstrate that the algorithm has good properties of confusion and diffusion. The key space is large enough to resist the brute-force attack. For the encrypted image the distribution of pixel-values has a random-like behavior and the values of adjacent pixels satisfy zero correlation.