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context: Since documents may have been signed using XML Signature [XML-Signature] or have had cryptographic digests made of them for other purposes, documents exchanged using SML-IF must be invariant with respect to XML Canonicalization. [Canonical XML] This is currently in what appears to be a non-normative section. I do not see any corresponding normative text for the MUST. Is this requirement still relevant, and is it already covered by normative text elsewhere or does it need to be added to normative text?
Kumar will write a proposal.
*** Bug 5134 has been marked as a duplicate of this bug. ***
Proposal: Remove all references to XML canonicalization from the specification. Reasons / More Info: -------------------- I investigated XML signature related issues to propose answers to the following questions: 1. Should the SML-IF spec define whether a producer must perform XML canonicalization before writing an SML-IF document? 2. If documents are already signed, what should an SML-IF producer do to the signatures if the producer wants to sign the entire document as well? That is, should the producer strip the existing signature(s) before adding documents to SML-IF? [1] The XML signature spec defines a customizable and extensible method for signing XML and non-XML content. A digital signature can be embedded in the signed document (there are 2 sub-flavors: enveloped / enveloping) or it can be detached from the signed document. The Signature element contains a single signature over one or more data objects. Each data object to be signed is represented using a single Reference element (this should not be confused with SML reference element). Each Reference element allows zero or more transformations over original data before the digital signature is computed. The XML canonicalization is just one such possible transform. A transform may omit parts of the original data or add new one. There is no restriction on the type or number of transforms that an application may use. One canonicalization algorithm removes comments. One other form preserves comments. Each application must be free to use the transforms that best fit its needs. The SML WG cannot predict specific requirements for all applications based on SML therefore we must not impose any restriction involving specific transformation. Note that this does not harm interop. Regardless of the number and type of transformations used, both producer and consumer apply them identically and thus arrive at the same message digest (if there is no tampering). [2] The XML signature is encoded using XML elements. Even if a document already has an XML signature, it can be safely packaged inside an SML-IF document. Since the SML-IF doc is itself an XML doc, it can be signed like a regular XML doc. A producer does not need to remove existing signatures. Moreover, if it is desired that existing signatures should not be included in signature calculation of the SML-IF document, a producer can logically remove the signatures (by defining appropriate transforms) without having to physically remove the signatures. An application must be free to use either method. Some references with relevant info: 1. http://www.w3.org/TR/2001/REC-xml-c14n-20010315 2. http://www.w3.org/TR/2002/REC-xmldsig-core-20020212/ 3. http://www.w3.org/Signature/Drafts/PROP-xmldsig-faq-20000218/Overview.html 4. http://msdn.microsoft.com/msdnmag/issues/04/11/XMLSignatures/
Please remove the reference to XML Canonicalization from the SML IF spec. In particular, remove this text Since documents may have been signed using XML Signature [XML-Signature] or have had cryptographic digests made of them for other purposes, documents exchanged using SML-IF must be invariant with respect to XML Canonicalization. [Canonical XML]
fixed as per comment #4 This section has been removed from the spec : Since documents may have been signed using XML Signature [XML-Signature] or have had cryptographic digests made of them for other purposes, documents exchanged using SML-IF must be invariant with respect to XML Canonicalization. [Canonical XML]