In recent years, digital video technologies have been used widely in the field of telecommunications and television and satellite broadcasting. The great expansion in digital broadcasting trade. The protection of viewing rights of films and broadcasting presented as a matter of commercial exclusive rights and its security requires using techniques that allows only the authorized to see the broadcast. This thesis provides the solution in the partial encryption technology and the proposition of symmetric dual key Dynamic block algorithm (SDD) with a speed sufficient to meet the requirements of real time with high level of complexity. In addition, this technique preserves the structure of the file.

SDD algorithm uses two keys for encryption as well as a block of bits of variable size (dynamic), and block size is mapped to (3 or 4 or 5 or 6 bits) as an element that belongs to the range of the finite fields and are based on calculations used in the algorithm on the theory of Galois's mathematical finite fields GF (2n).

The proposed encryption algorithm achieves the best results of the time factor, and it also provides a high level of complexity for its resistance to attacks.