Re: draft-klensin-emailaddr-i18n-00

I know this is going off-topic, but FWIW I think both Adam Costello
and John Cowan have valid points here. (Disclaimer: IANAC)

Adam's definition of a cryptographically strong hash tallies with my
understanding.  If it is computationally feasible (by exploiting the
birthday paradox or otherwise) to generate two strings that hash to
the same value, then the hash function is not cryptographically
strong.  And what John is proposing is somewhat more computationally
intensive than simply generating two random strings that hash to the
same value.  Once the hash function fails to satisfy the traditional
definition, you almost certainly have many other problems than the one
John describes.

On the other hand, cryptography is all about prudent design choices.
Since you can never prove that a cryptographic system is secure, you
always want to design it to be as secure as possible.  (ie you're
never _sure_ it's secure enough, so the last thing you want to do is
to weaken it unnecessarily.)

Signing normalized text would seem to be a prudent design choice, even
though signing unnormalized text is still secure, provided the hash is
secure.  If the other costs associated with this approach aren't
prohibitive, it would seem to be the correct course of action.

	-roy