Image Encryption using Improved Keystream Generator of Achterbahn-128

Abstract

The images transmission become more and more widely used in everyday life and even have been known to be vulnerable to interception and unauthorized access. The security of their transmission became necessary. In this paper an improved version of the Achterbahn-128 for image encryption and decryption have been proposed. The proposed design is based on seventeen binary primitive nonlinear feedback shift registers (NLFSRs) whose polynomials are primitive and a nonlinear Boolean function. The outputs of seventeen registers are combined by the nonlinear Boolean function to produce keysteam sequence. The proposed scheme is compared to a Achterbahn-128. The results of several experimental, statistical analysis and sensitivity analysis show that the proposed image encryption scheme is better than Achterbahn-128 and provides an efficient and secure way for image encryption and transmission.

An Algorithm for Image encryption based on chaotic maps

“…The Number of Pixel Change Rate (NPCR) and Unified Average Changing Intensity (UACI) are two percentages used to determine the effect of changing the value of one pixel from the original image to the encryption image [19] .…”

Secure Transfer of Color Images Using Horizontal and Vertical Scan

“…In order to implement the proposed approach for image encryption and decryption, we propose to use the key stream generator presented in [7]. The generator is a stream cipher system that consists of seventeen non linear feedback shift registers (NLFSR) denoted of lengths ,where 1 ≤ ≤ 17, and a non linear combining function of 17 variables.…”

“…The variables Each shift register is described by its feedback function. The algebraic normal forms of the feedback functions are given by [7].…”

“…The combining function H is balanced, number of variables is 17; it has an algebraic degree of 7; the correlation immune is of order 9; H has maximum nonlinearity of 64512. The algebraic normal form of the Boolean function is given by [7].…”

“…They are widely used in secure communication like: mobile communication and Bluetooth, because of their high throughput, less complex hardware circuitry and very little error propagation which has attracted much attention. Improved Achterbahn-128 key stream generator [7] is a bit oriented synchronous stream cipher based on the combination of seventeen NLFSR (Non Linear Feedback Shift Register) of Boolean function with good properties that ensure an adequate security. But these systems are unsuitable with image encryption due to the length of the key which has the same size as the image to be encrypted.…”