Encryption of multimedia content in partial encryption scheme of DCT transform coefficients using a lightweight stream algorithm

In recent years, security of multimedia systems such as image and video has become one of the main needs in computer and communication networks. To encrypt multimedia content, lightweight and fast algorithms are usually used in frequency transform domain and in a partial encryption form, having time efficiency, high execution speed and correspondence with compression structures. In this article, a lightweight and fast algorithm is proposed and two designs in partial encryption scheme of DCT transform coefficients are introduced based on three fundamental principles and confrontation the partial encryption attacks (cryptographic attack, replacement attack and statistical model based attack). Moreover, the proposed algorithm is compared with A5/1 and W7 stream ciphers. The results of analyses and simulations by MATLAB software show that the proposed encryption algorithm and two introduced designs are applicable for real-time security applications of multimedia which require high-speed computations and sufficient security levels.