Multimedia Security and Digital Rights Management

The large-scale use of digital media distribution rests on its ability to provide legitimate services to all parties. This requires allowing the convenient use of digital media while equitably compensating all members of the information distribution chain such as content creators, providers and consumers. Multimedia security is a field of research that stems from this need.

We live in a world of pervasive mobile digital media acquisition, distribution and consumption; digital distribution allows the introduction of flexible, cost-effective business models that are advantageous for multimedia commerce transactions. The digital nature of the information also more easily allows individuals to manipulate, duplicate or access media information beyond the terms and conditions agreed upon in a given transaction, which has made content protection and rights management an influential issue in content delivery networks.

Multimedia Security

Multimedia security is a form of content-based protection. In the context of information creation, processing, transmission and storage, content alludes to a higher level representation or semantics of the data. Naturally, this implies that content may be comprised of multiple forms of media such as audio, imagery, video, text and graphics in an assorted variety of digital formats. As a result, the characteristics of the information can greatly vary. For example, the required bit rate, maximum acceptable error, decompression complexity, and display requirements may deviate significantly which creates several challenges in terms of content protection.

Traditional forms of computer and network security do not sufficiently address the needs of content security because they often process information at the bit-level which does not allow appropriate consideration of the semantics of the information. This consideration is necessary if we are to design security mechanisms that can handle the processing of high bandwidth information such as video that may undergo loss or format conversion and allow the possibility of retention of some control over the intellectual property once it is transmitted. For example, encryption and authentication functions must accommodate varying data formats and lossy compression. Furthermore, computer and network security alone cannot appropriately manage the issue of piracy. Multimedia security responds to these issues through the following attributes:

• protection is tied to a higher level of the content, opposed to the actual bits, to provide efficient and effective security that can be designed to be more robust to format conversion or recovery from communication error. For example, digital signatures can be based on high level features of information rather than the bit representations to allow authentication even in the face of lossy compression.
• security processing, for encryption or digital watermarking, is integrated with other signal processing tasks such as compression and decompression to be able to handle fluctuations in bit rate. Combining encryption or digital watermarking with signal processing not only allows the reuse of processing blocks for greater efficiency, but can provide a structured method to attach security processing to varying content forms and bandwidth.
• semantic information such as metadata are associated with the content security mechanisms to ensure that the content is used as negotiated in an information commerce scenario.

A significant application and motivation for the development and use of multimedia security (in addition to traditional computer and network security) is digital rights management (DRM).

Digital Rights Management

DRM is the digital management of user rights to content.  It entails linking specific user privileges to media in order to control viewing, duplication, access and distribution, among other operations.  Ideally, the goal of a DRM system is to balance information protection, usability, and cost to provide a beneficial environment for all parties in an information commerce transaction; this includes expanded functionality, cost effectiveness and new marketing opportunities.  Overall, management is achieved through the effective interaction of business models, legal policy and technology.  It is the conflicting characteristics and rapidly changing environments in each of these spaces that makes DRM a challenging and interesting problem.

Research Focus

Our research focus has spanned the fields of robust, fragile and semi-fragile digital watermarking, media encryption, digital fingerprinting, media authentication and tamper-assessment technologies for DRM applications.

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