Provided are techniques for providing security in a computing system with identity mediation policies that are enterprise service bus (EBS) independent. A mediator component performs service-level operation such as message brokering, identity mediation, and transformation to enhance interoperability among service consumers and service providers. A mediator component may also delegate identity related operations to a token service of handler. Identity mediation may include such operations as identity determination, or “identification,” authentication, authorization, identity transformation and security audit.