The xml-security-c project is aiming to create a flexible C++ library for developers of applications that require cryptographic functionality in line with the XML Digital Signature and XML Security standards.
The project is at a very early stage but has released a "Proof of Concept" to demonstrate validation of a reasonably complex XML Digital Signature document.
The project is now moving forward to implement signing functionality and all the other required elements of the XML Digital Signature standard.
For more information see the project homepage at :