Identity authentication sharing technologies which allow many service providers to share the result of identity authentication of an identity provider receive high attention as alternatives for current problematic identity authentications in the next-generation Internet environment, since they can provide crucial advantages including high usability, cost effectiveness of service providers, and privacy protection. However, in order for the identity authentication sharing technologies to be widely deployed in global Internet scale, the interoperability problem among different identity authentication sharing protocols and the trustworthiness issue among the participating identity providers, service providers, and users should be resolved in advance. This paper firstly analyzes current status of the protocol interoperability issue and existing trust frameworks for identity authentication sharing. And then, based on the result of analysis, this paper proposes a next generation identity authentication sharing architecture for global Internet.