When using the external form of xades to countersign a DigitalAgreement...

[David Goodenough <david.goodenough@broadwellmanor.co.uk>]

should the second signature just be for the DigitalAgreement XML or should it also sign the original signature of the DA. If so does the DigitalAgreement come first in the datastream from which the counter signature is derived, or does the original signature come first.

 

If the just the DA case should the original signature be sent back to the originator or can it simply be stored at the original DA receiver. If the original should be sent back how is the original differentiated from the counter signature so that the receiver knows which is which.

 

In the DA + original signature case both signatures would have to be present in the data aggregate that is sent back. Again is there a standard way to mark one as the original signature and the second as the counter-signature

 

In either case where we need two signatures accompanying the reply one way of ordering the signatures would be to use the timestamp. This raises a new question: How would be know what order they were signed in given that unless I have misread the Xades spec the timestamps like those in UBL are local to the signer rather than including a timezone.

 

As far as I can see the DIgitalAgreement is the only case where there is a counter signature, all others are simple single document signatures so this problem does not arrive.

 

David