Analysis of trigonometric chaotic sequence by proposing an index-based bit level scrambling image encryption

Abstract

Chaotic map is applied to numerous research fields, such as encryption of data and information. In this paper, a novel bit-level scrambling encryption based on three-dimensional trigonometric chaotic sequence is proposed. This encryption is operated on grayscale images because pixel value of which is between 0 and 255, which can be converted into 8-bit binary number, then each image can be converted into eight binary images. Combine binary images a three-dimensional matrix as input, which have three index values width, height, and page. Generate three numbers by the chaotic sequence to locate the value of the matrix need to be changed. After the value is located, change its value 0 to 1 or 1 to 0, this is the basic encryption scheme. This paper makes a three-dimensional binary matrix with 32 images to test the encryption scheme, and get average value of images’ number of pixel change rate at 0.9603, unified averaged change intensity at 31.27%, information entropy at 7.9891, also the histograms. And correlation coefficients of each pixel from three directions are small. There are comparisons with other encryptions too. The key space of this encryption is more than 10[Formula: see text].