Re: [dane] email canonicalization for SMIMEA owner names

Paul Wouters <paul@nohats.ca> Fri, 12 December 2014 15:38 UTC

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From: Paul Wouters <paul@nohats.ca>
Date: Fri, 12 Dec 2014 10:38:13 -0500
To: Ben Laurie <benl@google.com>
Archived-At: http://mailarchive.ietf.org/arch/msg/dane/9xTBCEruFfJwZpFOvbhuhHBOpNE
Cc: dane WG list <dane@ietf.org>
Subject: Re: [dane] email canonicalization for SMIMEA owner names
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Whoever starts using variant email addresses should publish records for it? As John said, clients shouldn't start guessing addressing schemes used by others

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> 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?
> 
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