TDB: A Database System for Digital Rights Management

Some emerging applications challenge the assumptions that have influenced the design of database systems in the past. One example is Digital Rights Management (DRM) systems, which ensure that digital goods such as music and books are consumed (i.e., played or viewed) according to the contracts associated with them. Enforcement of contracts may require access to some persistent state such as usage meters and account balances. For good performance and disconnected operation, it is desirable to maintain this state in the consumer’s device. The state is managed by a DRM database system, which must protect the data not only against accidental corruption, as most database systems do, but also against malicious corruption. DRM database systems may be embedded in consumer appliances with limited resources. Consequently, DRM database systems typically manage small databases with cacheable working sets. They need not be optimized for high throughput or concurrency, and they do not need to provide sophisticated query processing. Instead, they should be tightly integrated with the application programming language to reduce code complexity, minimize the code footprint, and simplify administration. In this paper we describe the architecture and implementation of TDB, an embedded DRM database system. TDB is tightly integrated with the C++ programming environment: it provides typed storage of C++ objects and uses C++ as the data definition language. We concentrate on those aspects of TDB’s design where it departs from the common database design principles to accommodate DRM applications. We also show that, although it provides additional functionality for DRM applications, TDB performs better then Berkeley DB, which is a widely used, freely available embedded database system. We also show that TDB has a code footprint comparable to other embedded database systems.