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Re: Feedback on DKIM draft (long)

2005-07-14 19:59:18

On July 14, 2005 at 18:24, "Hallam-Baker, Phillip" wrote:

More generally, I think the "simple" appraoch does too little 
and the "nowsp" does too much. As you say, dropping all the 
internal space from the body leaves the door open too far.

I don't see how this is likely to result in a vulnerability unless the
sender is complicit in the construction of the message.

What you see now and what happens in the future may be two different
things.  I think if you have a chance to minimize the amount of
mutations allowed (with no real cost in performance) you should do
it.

Now, I can see something like DKIM (or Meta-Signatures) used for
applications where integrity of the data is important, and something
like losing all whitespace should cause a verification error.

Let us remember here that empirically it has proved much easier to fix
broken crypto systems than to deploy over-engineered crypto systems. 

In this case, I see no over-engineering done.  I see suggestions
that are practical and provide no real impact to performance.
If I am not mistaken, the body canonicaliztion algorithm I proposed
is very similiar to what OpenPGP does.  The only addition is
skipping all trailing LWSP at the end of the message.

The header canonicalization is a little more complex, but I see
nothing there that cannot easily be implemented.

--ewh


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