For Vault 2011, I told you how to sign and unsigned DLL. Those steps worked great if you have a single, isolated DLL. For Vault 2012, there are multiple interlinked DLLs, so the steps get much more complicated.
Instead of going over complicated steps, I'll just post the strong-named versions of the DLLs. These DLLs are not officially supported, but they are the same ones used in the Vault SharePoint integration. So some level of testing has been performed.
Do NOT use these DLLs for Vault extensions. They are only to be used for EXEs and plug-ins to non-Autodesk products. The Autodesk apps use the non-signed versions of the DLLs, and you can't mix the two together.