This paper proposes a novel design and implementation of distributed RBAC (dRBAC) and Single Sign-On (SSO) system that spans over multiple administrative domains with high availability. The core idea is based on Multi-Agent Systems (MAS) technique owing to its modularity, autonomy, distributedness, flexibility, and scalability. All agents serve their specific purposes. Leveraging agents simplifies high availability. PKI is used for trust enablement between intra- and inter-domain agent communications. The Security Assertion Markup Language (SAML) is adopted for supporting the exchange of authentication and authorization information in the architecture. The approach supports strong two-factor authentication with X.509 digital certificate. The authorization scheme is based on the Privilege Management Infrastructure (PMI). Finally, we reported our extended implementation status and demonstrated that our proposed model is efficient and flexible to implement in the multiple SSO and PKI domains.