A novel image encryption algorithm based on improved key selection and digital chaotic map

Chaotic systems are widely used in various fields, but under the finite precision device, chaotic systems would fall into a cycle and subsequently the performance degrade. Thus, the suppression method of the dynamic degradation of digital chaos is receiving increasing attention. This paper proposes a new improvement model to suppress the dynamical degradation under finite computing accuracy equipment. By using the difference between two maps of the same type but with different initial values, and the state feedback function to improve the performance of the digital chaotic map and extend the time before the chaotic map enters the cycle. Take the 1D Logistic map and x-dimensional of Baker map as examples to prove the effectiveness of the improvement model. Then we proposed a new key selection method, in what part of information of the image would be selected by using a chaotic map to generate a special value. The special value would be used as part of the key. Based this method, a new image encryption algorithm was proposed. The information entropy of the image encrypted by our encryption algorithm is 7.9972, the NPCR and UACI are 0.996095 and 0.334635, respectively, what both are very close to ideal values. The experimental simulation results show that the image encryption scheme exhibits good performances and high security and effectively resists various attacks.