An embedded cryptosystem for digital broadcasting

Current day multimedia systems require secure, reliable and fast data transfer. Conventional cryptographic systems attempt to encrypt the entire data directly, thereby requiring significant computation and noise free channels. This makes existing methods less attractive for real time broadcasting. Spread spectrum techniques offer good noise immunity over multiple access channels. We propose a new scheme that embeds a public key cryptosystem inside a spread spectrum framework to achieve security and noise immunity suitable for real time applications. Further, the encryption complexity of our scheme is independent of the volume of data broadcast since the data is not encrypted directly. We also introduce a novel multilevel spreading technique which overcomes the security limitations of bipolar spreading and provides a means of countering the effects of channel noise.