Re: [dane] email canonicalization for SMIMEA owner names

Ben Laurie <benl@google.com> Fri, 12 December 2014 11:37 UTC

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Date: Fri, 12 Dec 2014 11:37:14 +0000
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From: Ben Laurie <benl@google.com>
To: "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 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?