SAN FRANCISCO - Microsoft is dusting off its year-old and mostly forgotten TrustBridge technology and recasting it as middleware to support federation of identities across disparate platforms, company officials said Wednesday.

Microsoft said at the annual Burton Group Catalyst Conference that TrustBridge will become a security server capable of producing a user authentication and authorization token in a variety of formats. It will also facilitate the sharing of that token across corporate boundaries.

The server is a key part of Microsoft's effort to create an identity management framework that will work across disparate platforms. Just last week, the company unveiled its retooled meta-directory server, Microsoft Identity Integration Server, and released its Active Directory/Application Mode directory as part of its push into the identity management market.

"We are trying to simplify federated identity management, integrate identity infrastructures and provide a security infrastructure to support Web services applications," says Michael Stephenson, lead product manager for Windows Server.

Despite Microsoft's newfound exuberance toward federated identity, it is still mum on how it might integrate with the Liberty Alliance, a group that is creating a framework for federated identity management.

"We continue to have a good relationship with Liberty, and we continue to work on an interoperability solution," says Stephenson.

Microsoft plans to release TrustBridge around the time it ships the Longhorn version of the Windows operating system in 2005 or 2006. TrustBridge will require software on both the server and client side that supports WS-Security, an emerging Web services security protocol.

Microsoft officials still would not confirm reports that they will have a server version of Longhorn. The company also would not say how TrustBridge would be packaged and licensed.

TrustBridge was introduced more than a year ago as a bridge for sharing Kerberos authentication tickets among business partners. At the time, critics said the scope was too narrow, in that users had to have TrustBridge set up on both sides of the transaction and were required to use Kerberos.

Microsoft said it has gone back to the drawing board with the advent of WS-Security and a number of supporting security protocols Microsoft has developed in conjunction with IBM, including WS-Policy and WS-Federation, which was announced this week.