Real-time Partial Encryption of Oigital Video using Symmetric Dynamic Dual Keys Algorithm (SDD)


In recent years, as digital video technologies have been broadly used in TV,communication and multimedia. Security and privacy issues of the transmitted data have become an important concern in multimedia technology. Digital video stream is quite different from traditional textual data because interframe dependencies exist in digital video. Special digital video encryption algorithms are required because of their special characteristics, such as coding structure, largeamount of data and real-time constraints. This paper presents a real-time partial encryption to digital video technique based onSymmetric Dynamic Dual (SDD) keys algorithm which is fast enough to meet the realtime requirements with high level of security.This approach uses dual key for encryption with variable (dynamic) block bits size,each block bits size (3 or 4 bits ) are interpreted as an element of a finite field.. The first key is called control key determines the length of bits block (3 or 4 bits block) size toencrypt, and the second key is used for encryption by using a equation:Y = X. A+ BWhereX is bits block, AandB are the encryption keys.The mathematical operations addition and multiplication in this equation are based onmathematical theory of Galois field GF(2 ).In this technique the I-frame (Intra-frame ) of the digital video scene is extractedand decomposed the color picture into its three color channels:luma channel (Y) andtwo chrominance channels Cb and Cr,with note that the frames of digital video is inYCbCr color system, the SDD algorithm is applied to the Y channel.The encryption algorithm achieves best timing results, and it provides high level ofsecurity by its great resistant against brute force attacks, because it uses dual key anddynamic block cipher, hence it will be very difficult to guess the key. To decrypt theciphertext with 128 bits, the attacker needs 8.86569157e+188 of possibilities of keys asminimum and 7.91569097e+253 as maximum.