Abstract: According to the design patterns and implementations of many existing digital rights management systems, a minimal set of DRM system and a typical DRM system were designed. Against to the usual attack, some evaluation indices were proposed in this article. One of the indices is defense intensity after attack. AHP is used in the evaluation model of the security of DRM system. To evaluate the security, encrypt algorithm, commercial secret and the ability of anticrack were proposed as foundation of security. In the last part, two existing DRM systems were evaluated using the indices and the quantitative indicators which were given.The result of contrastive experiment indicates that the security evaluation model of DRM system is rational.

Key words: Digital rights management,Defense intensity after attack,Security evaluation,AHP