Re: XML Signature 1.1 KeyInfo requirements

I have entered this into tracker as a comment,  LC-2502 (even though the document is in CR)

http://www.w3.org/2006/02/lc-comments-tracker/42458/CR-xmldsig-core1-20110303/2502

Looking at this and Scott's mail, I propose the following changes to section 4.5 of XML Signature 1.1 [1]. Do we agree that these are the changes we want?

(1) Change last sentence in section 4.5 paragraph 2 and add sentences, to read

[[
While applications may define and use any mechanism they choose through inclusion of elements from a different namespace, compliant versions MUST implement KeyValue (section 4.5.2 The KeyValue Element) and SHOULD implement KeyInfoReference (section 4.5.10 The KeyInfoReference Element). The KeyInfoReference is preferred over use of RetrievalMethod as it avoids use of Transform child elements that introduce security risk and implementation challenges. Support for other children of KeyInfo is OPTIONAL.
]]

This changes the SHOULD from RetrievalMethod to KeyInfoReferenceElement and makes explicit that support for KeyInfo children is optional.

(2) Add at end of section 4.5.3 "The RetrievalMethod Element" the following note:

[[
Note: The KeyInfoReference  element is preferred over use of RetrievalMethod as it avoids use of Transform child elements that introduce security risk and implementation challenges.
]]

(3) add sentence to end of 1st paragraph of section 4.5 "The KeyInfo Element"

[[
Details of mechanisms used with element children of KeyInfo are out of scope for this specification, e.g. PKI certificate contents or ordering, CRL management and so on.
]]


If we change the normative language this document would need to go back to Last Call for a short review of the noted changes, but this should not be a schedule issue at this time, given that the ECC PAG continues. I would recommend we try to resolve this on the list and complete another Last Call if needed before August.

Please indicate agreement or suggested changes to the proposal on the list.

regards, Frederick

Frederick Hirsch
Nokia


[1] http://www.w3.org/TR/2011/CR-xmldsig-core1-20110303/#sec-KeyInfohttp://www.w3.org/TR/2011/CR-xmldsig-core1-20110303/#sec-KeyInfo

On Jun 29, 2011, at 3:24 PM, ext Sean Mullan wrote:

> Section 4.5, paragraph 2:
> 
> "If KeyInfo is omitted, the recipient is expected to be able to identify the key based on application context. Multiple declarations within KeyInfo refer to the same key. While applications may define and use any mechanism they choose through inclusion of elements from a different namespace, compliant versions must implement KeyValue (section 4.5.2 The KeyValue Element) and should implement RetrievalMethod (section 4.5.3 The RetrievalMethod Element)."
> 
> These requirements seem like they should be revisited, especially since a later section says to avoid RetrievalMethod because of potential security concerns (see Note in section 4.5.10). Also, does this imply that all KeyValues must be supported? I would think it should only be supported if there is a required signature algorithm for the corresponding key type. Had there ever been any discussion about updating the list of required KeyInfo types?
> 
> Thanks,
> Sean
>

Received on Friday, 1 July 2011 14:28:44 UTC