Multimedia data encryption via random rotation in partitioned bit streams

A new method to encrypt a compressed multimedia bit stream, which is the output of any compression system using an entropy coder in the last stage, is proposed in this research. The basic idea is to partition a coded bit stream into random-sized blocks and perform a random rotation in each block. The proposed encryption scheme demands low computational overhead and does not increase the size of compressed bit stream. Security analysis to both the ciphertext-only attack and the known/chosen-plaintext attack shows that the proposed algorithm achieves high security.