Design Of Image Encryption Algorithms Based On Chaos And DNA Encoding

Most people use the pictures to record everything in daily life and work. The application of image has become more and more important. Although a lot of image encryption algorithms exist, they still have some disadvantages, such as the correlation of adjacent pixels algorithm is too high, or it cannot resist chosen plaintext attack etc. Based on this, some researches have been made as follows:(1) According to some irrational decimals’ infinite cyclic, a new image encryption algorithm based on cipher stream which is produced by the infinite decimals. Key stream’s randomness is proved. Using the sequence of irrational decimal point, encrypt the image after inverting the sequence into binary sequence. The algorithm can resist various attacks and has good encryption effect.(2) An image encryption algorithm based on chaotic system and the plaintext is proposed. The key is generated by the XNOR operation using the plaintext and chaotic sequence. After encryption the plaintext is deleted and the key is saved. Thus the attackers only have to use force-attack way to attack. Then the algorithm’s security is improved. The experimental results show that, the attacker cannot use other ways to attack the cipher text, only through the exhaustive attack. While the algorithm’s key space can resist the brute force attack, which proves the validity and security of the algorithm.(3) As the circular shift is easy to realize and it has no size limit to image, an image encryption algorithm based on chaotic system and cyclic shift is proposed. Due to color image information can be stored in a three-dimensional matrix; three-dimensional matrix scrambling technique is used to encryption algorithm. These two techniques can reduce the correlation between pixels. Meanwhile they also ensure the security of encryption algorithm. Cyclic shift is to transform the binary sequence of pixel values, and the three-dimension scrambling technology is to change the image pixel values’position which weakens the correlation between image pixel values. Experimental results and security analysis prove the advantages of the two algorithms.(4) DNA encoding technology is used in more and more image encryption algorithm. Based on researches on DNA encoding technology, a similar DNA encoding scheme is proposed and applied in image encryption algorithm. Using four bit binary sequence as one code, thus the numbers of encoding and encrypting scheme are both increased to256times of DNA encoding. The algorithm’s security is strengthened and it is proved by experimental results.Taking MATLAB software as the platform, with Lena and the lion figure for material on the computer, the image encryption algorithms are simulated. The performances of the algorithm are analyzed through experiments. The experimental results show that the proposed algorithms have the good encryption effect and it can resist most attacks. Compared with the referred algorithms the proposed algorithms have advantages. It is effective to encrypt image using the image encryption algorithms in this paper.