3. Universal Identity Management Based on Delegation in SOA

Relationship-focused and credential-focused identity management are both user-centric notions in Service-oriented architecture (SOA). For composite services, pure user-centric identity management is inefficient because each sub-service may authenticate and authorize users and users need to participate in every identity provisioning transaction. If the above two paradigms are unified into universal identity management, where identity information and privileges are delegatable, user-centricity will be more feasible in SOA. The credential-focused system is a good starting point for constructing a universal identity management system. However, how to implement a practical delegation scheme is still a challenge although some delegatable anonymous credential schemes have been theoretically constructed. This paper aims to propose a practical solution for universal identity management. For this, a pseudonym-based signature scheme is firstly designed, where pseudonyms are self-generated and unlinkable for realizing user privacy. Next, a proxy signature is presented with the pseudonyms as public keys where delegation can be achieved through certificate chains. Finally, the WS-Federation is extended to build a universal identity management solution.