From mboxrd@z Thu Jan  1 00:00:00 1970
Message-Id: <200211271818.gARII0w00432@augusta.math.psu.edu>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] OS install floppy hangs during boot on Bochs 1.4.1
In-Reply-To: Your message of "Mon, 25 Nov 2002 22:56:54 MST."
             <20021125225654.B2266@tibia.amotlpaa.bogus>
From: Dan Cross <cross@math.psu.edu>
Date: Wed, 27 Nov 2002 13:18:00 -0500
Topicbox-Message-UUID: 28ee90de-eacb-11e9-9e20-41e7f4b1d025

> For my next trick... I wonder whether the MD5 algorithm is such
> that the hash for the concatenation of two blocks of bits can be
> determined quickly from the hashes for the two blocks.

Good God, I hope not.  MD5 shouldn't be a homomorphism.

> Then, you
> see, you could have the hash(es) for the invariant part(s) of the
> disk image lying around, and combine it (them) on the fly with the
> hash for the user's individual plan9.ini.

You could hash the hashes of the two bits, which would be
computationally cheap (relatively speaking).

	- Dan C.