From: "David F. Ogren" <ogren@cris.com>
Date: Tue, 2 Jul 1996 06:32:05 +0800
To: watt@sware.com
Subject: Re: rsync and md4
Message-ID: <199607011700.NAA19537@darius.cris.com>
MIME-Version: 1.0
Content-Type: text/plain


-----BEGIN PGP SIGNED MESSAGE-----

> Look the point is that Ogren seems to think this is some sort of a
> minor technicality and that we can safely ignore it most of the
> time. Thats simply not prudent. Once you find that the key properties
> of your cryptographic hash have fallen and you have to be
> exceptionally careful about what you put through the hash lest an
> attacker somehow influence it, you've lost the game. MD5 is no longer
> trustworthy. I agree that one needn't run screaming in the streets,
> but Ogren made it sound as though this wasn't a matter of
> concern. Thats simply wrong. Saying that leads people to a completely
> incorrect conclusion.

And I told myself I wouldn't respond to this thread anymore.  Oh well.  I 
just don't want to be misinterpreted.

I never meant to imply (and don't think that I did), that the attacks 
against MD5 were insignificant.  As I said, I'm moving to SHA in any 
software I develop from now on.

What I said was the attacks were insignificant in the application being 
considered (rsync) and that MD5 was not completely broken.  Come on, all 
the guy wanted was a fast 128 bit checksum.

For example, I am still using PGP clearsigning which, of course, uses MD5. 
Dobbertin indicates that his attack cannot be used against me as long as I 
only sign messages that I create myself.  Yes, PGP would work better with 
SHA.  I'd be able to sign documents that others created with (more) 
certainty.  But that doesn't mean that I should stop using PGP.


P.S. I apologize to the list for flooding this list recently.  
Unfortunately, I took it a little too personally when Perry told me to 
"stop spewing inaccurate information" and to "quit posting".  It was late, 
and I let him bait me more than I ordinarily would.

Now I find myself running in circles trying to make sure that I've made 
myself clear and that no one else (other than Perry) is misintepreting what 
I'm saying.
- --
David F. Ogren                | 
ogren@concentric.net          | "A man without religion is like a fish
PGP Key ID: 0x6458EB29        |  without a bicycle"
- ------------------------------|----------------------------------------
Don't know what PGP is?       | Need my public key?  It's available
Send a message to me with the | by server or by sending me a message
subject GETPGPINFO            | with the subject GETPGPKEY
-----BEGIN PGP SIGNATURE-----
Version: 2.6.2

iQEVAwUBMdgDbuSLhCBkWOspAQGPeQf/QJB109Gjd3s/ALodykZgH0S6FCs3wHK7
OiTUpxBF5lwojhBSrz7ej1RnAW+Uq5Lcz/GyWqH6rvYPPI1uZ3023UAV3nqH8qXY
nnznPfvTkUQgSjaQu/YRvWlTWwrNsW/KIR6iVbwVDnbUnvuAjUJskWyAg1Wz4zIV
8PV8RnrHSTT06j5LrCtiD0eWr/NgmpgIFS5+ID5z9/ikMV6xF4zSrlubELFFJUUT
M3nZWDlr7SaU0hFLQt3yu6oSqAjKSGrPsU1QCJ/Y1zdS49R/cLIzOzbQ42R1Cyot
hMnAayTqNdUI/goa2WAbda3gYpRodTA2GpciNj7u3xs0Ik/1TIEqlw==
=4x7D
-----END PGP SIGNATURE-----