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Type: Improvement
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Status: Open
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Priority: Major
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Resolution: Fixed
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Component/s: AS4 Profile
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Labels:None
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Proposal:
In AS4, the support for non-repudiation of receipt attempts to leverage the capabilities of WS-Security. If NRR is requested, the receiving MSH can reuse the ds:Reference computed by the sending MSH and validated by the WS-Security module of the receiving MSH. The sending MSH can store the SignedInfo and match the returned receipt to it. Profiling rule (c) in 5.1.8 already requires signing of receipts for signed messages.
Section 5.2.1 of AS4 defines a Pmode parameter to request NRR. The Core Specification already defined a parameter to specify the application of signatures. The two obvious, practically useful configurations are:
- Signed messages, NRR receipts.
- Unsigned messages, NRR receipts
In theory, having this parameter as an independent parameter means AS4 allows two other combinations:
- Signed messages, reception awareness receipts.
- Unsigned messages, NRR receipts.
The first of these two configures an exchange where NRO is provided and NRR is not. It could have some theoretical value, though I can't see it being of any practical use, but is doesn't complicate implementations much.
The second is quite problematic as the sending MSH does not provide any ds:Reference so that the receiving MSH would have to compute these itself. However, the NRR receipt would have no value to the sending MSH as it cannot compare the hash values to any values it has computed itself. So to simplify implementations, my proposal would be to disallow this second situation: we restrict NRR receipts to signed messages.