Security of the multimedia data including image and video is one of the basic requirements for the telecommunications and computer networks. In this paper, we consider a simple and lightweight stream encryption algorithm for image encryption, and a series of tests are performed to confirm suitability of the described encryption algorithm. These tests include visual test, histogram analysis, information entropy, encryption quality, correlation analysis, differential analysis, and performance analysis. Based on this analysis, it can be concluded that the present algorithm in comparison to A5/1 and W7 stream ciphers has the same security level, is better in terms of the speed of performance, and is used for real-time applications. 1. Introduction Nowadays, multimedia data such as image and video is expanding in communications and computer networks [1]. Due to widespread use of multimedia data and despite widespread threats and attacks in communication systems, security of this data is necessary [2, 3]. Multimedia encryption challenges originate from two realities. Firstly, multimedia data have great volumes. Secondly, they need real-time uses [4]. So using encryption for security results in additional computations for information processing. As a result, a balance between security and synchronization requirement is necessary [5]. To reach this aim, we use lightweight and high-speed encryption algorithms. One of the methods to ensure security is considering all data as binary strings and encrypt them using block encryption algorithms such as DES. These algorithms are very complex and involve large amounts of computations, and their software implement is not fast enough for high-volume multimedia data [6]. Commonly stream encryption algorithms are used for image encryption [5, 7–9]. Stream ciphers are built using a pseudorandom key sequence, and then this sequence is combined with the original text through exclusive-or operator. Generally, stream encryption systems have suitable performance when speed and error probability of data transmission are high. In this paper, the simple and lightweight stream encryption algorithm is used for multimedia applications such as image, and also various statistical tests are performed in order to assure the security of the algorithm and compared to A5/1 and W7 stream cipher. The notable point in this algorithm is producing the key sequence by AES block cipher in order to enhance the security. A5/1 and W7 stream cipher algorithms are used for the key production from the linear feedback shift registers. A5/1 algorithm has
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