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Semantics in signatures

From: <Chris_Smithies@penop.com>
Date: Wed, 12 Apr 2000 13:35:47 +0100
To: "IETF/W3C XML-DSig WG" <w3c-ietf-xmldsig@w3.org>
Message-ID: <OF6D713979.4CD7972A-ON802568BF.0043572F@com>
1: some signature semantics are not application-specific in the usual sense
of that term. They may not belong to all signatures, but they belong to a
very large subset.

2: Joseph's example, in which the signed data contain an <approved by
="xxx"> element referring to the signature, has I think two drawbacks,
neither of them fatal.

2.1: It will be hard work to allow arbitrarily many signatures to be added
to a document using this approach. Subject to what John Boyer has to say,
it looks to me as if a document will need to be specially designed to allow
multiple signatures to be added.

2.2: Information about the signature logically belongs with the signature.
Forensic examination of signatures will be complicated by the need to
consult a plurality of resources in different locations in order to
reconstruct the evidence of a single historical event.

3: It is not the application which defines the meaning of a signature. The
application can only define whether the signature _can have_ any semantics.
It is the intent of the signatory which determines what a signature
actually means. (For more on application semantics, see e.g.

For these reasons I think that Joseph's proposal is actually more untidy
than making use of the SignatureProperties. Perhaps he would like to point
out where I'm going wrong.

CPK Smithies
Received on Wednesday, 12 April 2000 08:29:08 UTC

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