[dkim-dev] Should granularity (g= tag) be case sensitive?

[Jason Long]

I was reviewing the DKIM specification the other day and realized that my
implementation has got something wrong. Granularity checking should be
case-sensitive. Here's my rationale:

  - RFC 4871 section 3.2 says all tag values, unless otherwise specified,
are case-sensitive.

  - RFC 4871 section 3.6.1 describes the granularity (g=) tag, but says
nothing about case-sensitivity.

  - Therefore, the granularity checking of a public key record should be
case-sensitive.


Agree?


Well, I checked this point on various responders by constructing a message
that tests this specific issue... Here's what I found:

the following responders are NOT case-sensitive:
    dkimtest.jason.long.name
    sendmail.net
    dk.elandsys.com
    blackops.org
the following responders ARE case-sensitive:
    altn.com - responded with (:DKIM_SELECTOR_GRANULARITY_MISMATCH)
    verifier.port25.com - responded with (key granularity "jl*g" doesn't
match local part "JLong")



So, which is it? Should granularity be case-sensitive?


Jason