Key management in multi-distributor based DRM system with mobile clients using IBE

Current digital rights management (DRM) systems support only two-party systems, involving the package server and purchaser. However, for a scalable business model of transacting digital assets, a multi-party DRM system is often necessary which involves more than one distributors, who can promote and distribute the content in regions unknown to the package server. We propose a key management scheme for a DRM system that involves more than one distributors with the DRM client´s flexibility of choosing a distributor according to his own preference. For instance, a mobile DRM client may contact to a distribution server who is nearest to him by location or who offers promotions/discounts on the price or offers more commissions. In our scheme, the package server does not trust the distribution servers or the license server. The encrypted digital content sent by a package server can only be decrypted by the DRM client who has a valid license and is protected from attacks by other parties/servers in the system. Moreover, we use identity-based encryption (IBE) that incurs less computation cost and storage as certificate managements are not necessary and certificate verifications are no longer needed. These features make our DRM system suitable for more effective business models/applications with the flexibility in deciding a wide range of business strategies as compared to the existing works.