Tools for DB mapping, reifing and signing?

Hi,

 

for a prototype I want to map some data out of a relational database and out of some XML documents to RDF, reify this information with some metadata (author, valid until, privacy, ...) and sign it afterwards.

 

What

+ tools / APIs (database mapping, signing)

+ ontologies / vocabularies (beside of DC)

can be used for this?

 

Is there an agreed upon opinion, if signatures should be includes in the RDF-model or should the serialization of the model be signed using XML-signature?

Chris