RFC 4871, "DomainKeys Identified Mail (DKIM) Signatures", May 2007

Note: This RFC has been obsoleted by RFC 6376

Note: This RFC has been updated by RFC 5672

Errata ID: 1379
Status: Verified
Type: Technical
Publication Format(s) : TEXT
Reported By: Tony Hansen
Date Reported: 2008-03-21
Verifier Name: Pasi Eronen
Date Verified: 2009-05-14

Section 3.5 says:

       sig-z-tag      = %x7A [FWS] "=" [FWS] sig-z-tag-copy
                    *( [FWS] "|" sig-z-tag-copy )
   sig-z-tag-copy = hdr-name ":" qp-hdr-value

It should say:

       sig-z-tag      = %x7A [FWS] "=" [FWS] sig-z-tag-copy
                    *( "|" [FWS] sig-z-tag-copy )
   sig-z-tag-copy = hdr-name [FWS] ":" qp-hdr-value

Notes:

From the October 2008 interop event, there are several issues with z=:

FWS in z= tag

1) Does not allow any FWS between the "|" and the following header name in sig-z-tag-copy

2) By the ABNF, the informative example that immediately follows is invalid:

z=From:foo@eng.example.net|To:joe@example.com|
----Subject:demo=20run|Date:July=205,…

3) The [FWS] is redundant there; sig-z-tag-copy ends with qp-hdr-value, which can already end with arbitrary FWS

4) No FWS allowed between the hdr_name and the following ":“:

The modified ABNF is not redundant and agrees with the example.

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