Using WF and BC for DigSignatures

[LANGE, BODO]

Hi there,
has anybody ever tried to  digitally sign a document coming via Idoc to the
Business Connector (3.5.2) using the user's
(initiator of WF) private key.
We are trying to implement this process using the new signing method written
in Java in the BC. In order
to get the user or his approver we are doing an RFC to the EBP system, where
we stored the approver in a separate table
and then retrieve the private key locally from a HW box attached to the BC.
 
I wonder if anybody encountered a similar problem and might have resolved
this in a different manner.
 
Any feedback is appreciated
 
Bodo Lange
SAP Italy