On 03/May/10 22:26, The IESG wrote:
The IESG has received a request from an individual submitter to consider the following document: - 'Authentication-Results Registration For Differentiating Among Cryptographic Results ' <draft-kucherawy-authres-header-b-01.txt> as a Proposed Standard The IESG plans to make a decision in the next few weeks, and solicits final comments on this action. Please send substantive comments to the ietf@xxxxxxxx mailing lists by 2010-05-31.
The I-D identifies a possible result forgery (section 6.2). Although I haven't fully grasped the reasons why such attack would be attempted, I think that condition is a case where the spoofed signature SHOULD be removed by the verifier. I'm not sure the latter spec would be an update of rfc 4871, since it says "/Signers/ SHOULD NOT remove any DKIM-Signature header field" [emphasis added]. (Other cases where signatures might be removed --mailing lists-- are currently being discussed on ietf-dkim.)
For a minor point, the example (A.1) the I-D makes does not illustrate the reason for introducing header.b. The exemplified signatures can already be distinguished by their header.i values. By setting that attribute also in this case, the example conveys the impression that header.b should not be omitted, even when it is unnecessary. If that's the intended meaning, it should be stated more explicitly, IMHO.
OTOH, the example shows a case where a signature had been validated before being broken (discussed on ietf-dkim and [1]). However, that is apparently the only part of the I-D discussing such topic.
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