Low cost highly secure image scrambler and descrambler

Multimedia data security is very important for multimedia commerce on the Internet such as video on-demand and real-time video multicast. The image encryption is widely used to secure transmission of data in an open internet works. Every data has its own unique features; therefore different data requires different type of encryption algorithm. Many of the available algorithms are suitable for textual data but they are not suitable for multi-media data such as images, videos. Moreover, traditional cryptographic algorithms which are available for data security are often not fast enough to process the large amount of data generated by different multimedia applications to meet the real-time needs. This paper presents an Encryption/Decryption method based on both Permutation and Substitution. In this method, the data is scrambled efficiently in the frequency domain, i.e., the permutation and substitution process is performed on the DFT coefficients of the input data. Three different keys of random sequence along with a specific equation are used for substitution and three more keys are used to change the positions of the DFT coefficient values for three matrices generated from the RGB color image. In this algorithm six different keys have been used, which are highly unpredictable and random. This increases the security of Multimedia data. This method requires low hardware cost and reduces computational complexity. This algorithm is able to work with different types of files; for example: image files (both gray-scale and RGB color image), audio files, text file, etc. The software is realized using MATLAB.