Secure signal processing: Privacy preserving cryptographic protocols for multimedia

The processing and encryption of multimedia content are generally considered sequential and independent operations. In certain multimedia content processing scenarios, it is however, desirable to carry out processing directly on encrypted signals. The field of secure signal processing poses significant challenges for both signal processing and cryptography research; only few ready to go fully integrated solutions are available. This paper first concisely summarizes cryptographic primitives used in existing solutions to processing of encrypted signals, and discusses implications of the security requirements on these solutions. The paper then continues to describe two domains in which secure signal processing has been taken up as a challenge, namely analysis and retrieval of multimedia content, and multimedia content protection. In each domain, state-of-the-art algorithms are described. Finally, the paper discusses the challenges and open issues in the field of secure signal processing.