Axway have made available under an open source (Apache 2.0) license a utility to extract public key information from an X509 certificate. The utility builds an XML KeyInfo element as defined by http://www.w3.org/2000/09/xmldsig# .

http://code.google.com/p/keyinfowriter/downloads/list

This utility is of interest to anyone involved in managing ebXML CPAs that use certificates for signing or encryption.  This utility is used by the JustId open source CPA toolkit.

The Justitiële Informatiedienst in Almelo, the Netherlands, has released the toolkit that it developed to support management of ebXML Collaboration Protocol Agreements (CPAs) under an open source (EUPL) license. The toolkit, and previous versions of it, have been used to create and manage the CPAs for organizations in various government sectors in the Netherlands.  Hundreds of millions of ebXML messages have been exchanged based on CPAs created using the toolkit. 

The following is from http://www.osor.eu/projects/cpatoolkit:

Description