On Mon, 15 Feb 2016, Harald Alvestrand wrote:
BTW, this text from the draft is obviously not saying what it intended
to say:
o The user name (the "left-hand side" of the email address, called
the "local-part" in the mail message format definition [RFC5322]
and the local-part in the specification for internationalized
email [RFC6530]) should already be encoded in UTF-8 (or its subset
ASCII). If it is written in another encoding it should be
converted to UTF-8 and then hashed using the SHA2-256 [RFC5754]
algorithm, with the hash truncated to 28 octets and represented in
its hexadecimal representation, to become the left-most label in
the prepared domain name. Truncation comes from the right-most
octets. This does not include the at symbol ("@") that separates
the left and right sides of the email address.
As written, it states that hashing is only applied to strings that are
not originally in UTF-8 - but the "for example" text below makes it
clear that this is not intended.
That text is not quoted from the 07 draft, because 07 states:
o The user name (the "left-hand side" of the email address, called
the "local-part" in the mail message format definition [RFC5322]
and the local-part in the specification for internationalized
email [RFC6530]) is encoded in UTF-8 (or its subset ASCII). If
the local-part is written in another encoding it MUST be converted
to UTF-8.
o The local-part is hashed using the SHA2-256 [RFC5754] algorithm,
with the hash truncated to 28 octets and represented in its
hexadecimal representation, to become the left-most label in the
prepared domain name.
Paul