Re: [dane] email canonicalization for SMIMEA owner names

Ben Laurie <benl@google.com> Fri, 12 December 2014 16:28 UTC

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Date: Fri, 12 Dec 2014 16:28:34 +0000
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From: Ben Laurie <benl@google.com>
To: Alexey Melnikov <alexey.melnikov@isode.com>
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Cc: Paul Wouters <paul@nohats.ca>, dane WG list <dane@ietf.org>
Subject: Re: [dane] email canonicalization for SMIMEA owner names
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On 12 December 2014 at 15:56, Alexey Melnikov <alexey.melnikov@isode.com> wrote:
> On 12/12/2014 15:38, Paul Wouters wrote:
>>
>> Whoever starts using variant email addresses should publish records for
>> it? As John said, clients shouldn't start guessing addressing schemes used
>> by others
>
> +1. Nobody other than the final MTA/MDA knows that certain forms are
> equivalent.

True, but does not make your scheme workable.

>
>> Sent from my iPhone
>>
>>> On Dec 12, 2014, at 06:37, Ben Laurie <benl@google.com> wrote:
>>>
>>>> On 11 December 2014 at 19:51, Rose, Scott W. <scott.rose@nist.gov>
>>>> wrote:
>>>> Realized the other action item I was assigned to from the interim
>>>> meeting was email canonicalization for SMIMEA.  I believe it stems from
>>>> Viktor Dukhovni's email to the endymail list:
>>>> http://www.ietf.org/mail-archive/web/endymail/current/msg00134.html
>>>>
>>>> I was wondering if we can borrow a page from RFC 4034 Section 6.2 and
>>>> include text in the draft Section 3, item 1 in the numbered list:
>>>>
>>>>      1.   The user name (the "left-hand side" of the email address,
>>>> called
>>>>        the "local-part" in the mail message format definition [RFC2822]
>>>>        and the "local part" in the specification for internationalized
>>>>        email [RFC6530]), is hashed using the SHA2-224 [RFC5754]
>>>>        algorithm (with the hash being represented in its hexadecimal
>>>>        representation, to become the left-most label in the prepared
>>>>        domain name.  This does not include the "@" character that
>>>>        separates the left and right sides of the email address.  The
>>>>        string that is used for the local part is a Unicode string
>>>>        encoded in UTF-8 **with all upper case letters converted to their
>>>>        corresponding lower case letters where appropriate.**
>>>>
>>>>
>>>> The text between the '**' is new.  The goal is to prevent a situation
>>>> when the email address is "JRandom@example.com" and the SMIMEA is created
>>>> using "jrandom" as the user name.   Would this be enough, or are there
>>>> scripts where this would result in different or potentially conflicting
>>>> owner names?
>>>
>>> Speaking of canonicalisation:
>>>
>>> 1. What about X+Y@Z - for almost all MTAs, this is the same as X@Z.
>>>
>>> 2. What about GMail's a.b.c@gmail.com == abc@gmail.com ==
>>> ab.c@gmail.com == a.bc@gmail.com?
>
>