Re: [dane] email canonicalization for SMIMEA owner names

Alexey Melnikov <alexey.melnikov@isode.com> Fri, 12 December 2014 15:58 UTC

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Date: Fri, 12 Dec 2014 15:57:38 +0000
From: Alexey Melnikov <alexey.melnikov@isode.com>
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To: Ben Laurie <benl@google.com>, "Rose, Scott W." <scott.rose@nist.gov>
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Subject: Re: [dane] email canonicalization for SMIMEA owner names
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On 12/12/2014 11:37, Ben Laurie 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.
This is a bit misleading: MSA or intermediate MTAs can't know that these 
are the same (unless MSA is also the final MTA).
> 2. What about GMail's a.b.c@gmail.com == abc@gmail.com ==
> ab.c@gmail.com == a.bc@gmail.com?
As above.