Re: [dane] email canonicalization for SMIMEA owner names

Alexey Melnikov <alexey.melnikov@isode.com> Fri, 12 December 2014 15:56 UTC

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Date: Fri, 12 Dec 2014 15:56:03 +0000
From: Alexey Melnikov <alexey.melnikov@isode.com>
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To: Paul Wouters <paul@nohats.ca>, Ben Laurie <benl@google.com>
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Subject: Re: [dane] email canonicalization for SMIMEA owner names
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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.
> 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?