Progressive scrambling for MP3 audio

Audio scrambling can be employed in audio distribution for the purpose of guaranteeing the confidentiality. Electronic commerce in audio products would be facilitated by the development of solutions which can ensure security/privacy, have efficiency in the compressed domain to reduce the bandwidth requirements, flexibility of implementing progressive audio quality control and be computationally inexpensive for use in real-time systems. This paper proposes an effective progressive scrambling algorithm that works with MP3 audio. We perform multiple-level scrambling based on keys to produce a set of audio outputs of differing qualities. During decoding, the keys provided, and rounds of descrambling performed, decide the quality of the audio output. Our experiments show that the proposed algorithm is effective, fast, simple to be implemented, and at the same time it does provide flexibility to control the quality of audio output progressively. We also present some experimental results to show its utility in real-time systems.