ietf-dkim
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Re: [ietf-dkim] Re: canonicalized null body and dkim

2007-01-11 07:46:24
Deciding to skip adding those two bytes for the case of N < X-2 is
purely an optimization.* Your implementation is free to make any
optimization that it chooses to do, as long as the result is
indistinguishable from calculating it in the unoptimized way.

I think that where Eric placed these words make it clear that adding the
CRLF is done during the canonicalization phase, and that the l=
truncation is performed off of the canonicalized text.

I'm happy with this last addition, and I think it polishes off the
issue. "Ship it, Dano." (And now I'm off to change my implementation to
match. :-) )

        Tony Hansen
        tony(_at_)att(_dot_)com

* where N and X come from l=N and X=length(canonicalized(body))

Hector Santos wrote:
Eric Allman wrote:

I've changed the text to read "If there is no body or no trailing CRLF
on the message body, a CRLF is added" in order to avoid any confusion.

Eric, this is good. I will comment that the only confusion is there is
an indirect implication that the final two bytes of the FEED must have a
<CRLF>.

Which is not true, right?

Because a) A signer can canonicalized the message, including adding a
<CRLF> if necessary, that yields size X, but B) the signer decides to
hash only L=N  bytes where N < X bytes.

That was the only "scratch head" thought I had about all this - The
reason to add a <CRLF> if a signer was not going to hash the entire body.

So I guess, if anything, a statement, sentence or comment that states
"the need to add a <CRLF> is only necessary if the entire body is going
to be hashed."
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