From mboxrd@z Thu Jan  1 00:00:00 1970
From: erik quanstrom <quanstro@quanstro.net>
Date: Tue,  9 Feb 2010 09:54:25 -0500
To: 9fans@9fans.net
Message-ID: <499ca953b8167a8bd777b0785a696bba@ladd.quanstro.net>
In-Reply-To: <13426df11002090550x73f75e99i8983be3c6596deba@mail.gmail.com>
References: <4B6DB95F.4090907@maht0x0r.net>
	<Pine.BSI.4.64.1002061338530.5454@malasada.lava.net>
	<78b9710340a6345eac9f8690d306e1bb@brasstown.quanstro.net>
	<Pine.BSI.4.64.1002070649520.5454@malasada.lava.net>
	<3dd5c634eddc6496085190a0e6de46a4@ladd.quanstro.net>
	<20100207192400.GN15480@gradx.cs.jhu.edu>
	<4B6F39E7.6050605@maht0x0r.net>
	<20100208233750.GR15480@gradx.cs.jhu.edu>
	<f4d8fa41002090513j5d28edf7v2e1ec91a832c42e1@mail.gmail.com>
	<13426df11002090550x73f75e99i8983be3c6596deba@mail.gmail.com>
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Subject: Re: [9fans] In case anyone worries about block hash collision in
	venti
Topicbox-Message-UUID: d111b17e-ead5-11e9-9d60-3106f5b1d025

> > If you are really paranoid and don't want any collisions in the next
> > 10 years: don't let strangers in your venti.
>
> Which, to close the circle, as Tim points out, you are always doing,
> each time you receive an email :-)

not all email is from strangers.

in mbox format, messages are concatinated.  for a block
size of b, the size of the existing mailbox is 0 ... b-1 mod b.
therefore, there is a 1/b chance of the attack succeeding, even
if the attacker knows the block size and pads to the next
block.  i suppose that this is a fair assumption, since we're
given that the attacker is attacking venti.

this is esentially the same reason that mbox format will eat alot
of storage, even if you're using venti.

- erik