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Because of limited server and network capacities for streaming applications, multimedia proxies are commonly used to cache multimedia objects such that, by accessing nearby proxies, clients can enjoy a smaller start-up latency and receive a better quality-of-service (QoS) guarantee-for example, reduced packet loss and delay jitters for their requests. However, the use of multimedia proxies increases the risk that multimedia data are exposed to unauthorized access by intruders. In this paper, we present a framework for implementing a secure multimedia proxy system for audio and video streaming applications. The framework employs a notion of asymmetric reversible parametric sequence (ARPS) to provide the following security properties: i) data confidentiality during transmission, ii) end-to-end data confidentiality, iii) data confidentiality against proxy intruders, and iv) data confidentiality against member collusion. Our framework is grounded on a multikey RSA technique such that system resilience against attacks is provably strong given standard computability assumptions. One important feature of our proposed scheme is that clients only need to perform a single decryption operation to recover the original data even though the data packets may have been encrypted by multiple proxies along the delivery path. We also propose the use of a set of encryption configuration parameters (ECP) to trade off proxy encryption throughput against the presentation quality of audio/video obtained by unauthorized parties. Implementation results show that we can simultaneously achieve high encryption throughput and extremely low video quality (in terms of peak signal-to-noise ratio and visual quality of decoded video frames) for unauthorized access.
Date of Publication: April 2005