Federated environment application running on cost-effective federated identity management system has been more widely adopted, and would potentially attract more organizations to adopt and invest if we enhance with security and trust mechanisms. The traditional certificate based authentication raises various issues such as firstly, the case when public portion of the key pair can be guessed or calculated by the attacker, it can further be used to masquerade against resource access, and secondly, when the storing of private key on user system can be compromised by viruses, Trojan horses etc. Also current computer platforms are lacking in platform trust establishment which makes it hard to trust remote platforms. In this paper, we discuss concerns related to federated services user authentication, authorization, and trust establishment in Federated Open Systems Interconnection and proposed trusted platform module protected storage to protect private keys, and platform attestation mechanisms to establish inter platform (and hence inter system) trust among interacting systems in open environment to overcome these issues. To assess our work we compared trusted platform module with existing authentication types and shows that trusted platform module provides better temper-resistance protection against attacks such as replay, Trojan horse's, and fake anti viruses' attacks etc. © 2011 Springer-Verlag.