Managing trust and secrecy in identity management clouds

User management services were one of the first to be offloaded to third party cloud vendors. Today, a large number of service providers rely on trusted identity providers for managing users and their resources. At the core of these interactions involving multiple providers are a set of web-based workflows that have emerged as de-facto standards. In this paper, we propose a framework especially addressing needs of analyzing security in such web protocols. To analyze trust between collaborating service providers on the web, we extend the well-known BAN logic. We study secrecy properties to examine security of user identity management across multiple domains, using a SAT based model-checking approach. The result is a hybrid approach that inherits simplicity and intuitive appeal of belief logics without being affected by soundness problems associated with these logics. We illustrate the method through analysis of a premier web identity management protocol where we use our method to automatically discover a new attack trace.