Re: [zooko@zooko.com: [Revctrl] colliding md5 hashes of human-meaningful

From: Linus Torvalds <torvalds@osdl.org>
Date: Jun 13, 2005, 21:39 UTC
Message-ID: <Pine.LNX.4.58.0506131434260.8487@ppc970.osdl.org>
In-Reply-To: <20050613210318.18965.qmail@science.horizon.com>

On Mon, 13 Jun 2005 linux@horizon.com wrote:

> 
> > But perhaps slightly impractical.
> 
> There are just few laws of physics it violates.

Yeah, yeah. You avoided a few laws of phsyics of your own.

For example, when you say

  "(With an n-bit hash and an automated way to make harmless changes
   to source files, I can generate 2^(n/2) variants of each and expect to
   get a match, even in the absence of a better attack.)"

you kind of ignore the fact that "n" here is 160, and so you're going to be searching for quite a few versions of each. Also, you have to compare the sha's of all of those 2**80 versions against each other which is a lot of work in itself.

Finally, you have to make sure that al the versions make sense, and that people will take them 100% unmodified.

My plan was more interesting, I feel.

		Linus