[121877] in cryptography@c2.net mail archive
Re: "Designing and implementing malicious hardware"
daemon@ATHENA.MIT.EDU (Ed Gerck)
Mon Apr 28 17:38:33 2008
Date: Mon, 28 Apr 2008 13:21:06 -0700
From: Ed Gerck <edgerck@nma.com>
To: "Perry E. Metzger" <perry@piermont.com>
CC: Cryptography <cryptography@metzdowd.com>
In-Reply-To: <874p9lg2s0.fsf@snark.cb.piermont.com>
Perry E. Metzger wrote:
> No. It really does not. Shannon's tenth theorem is about correcting
> lossy channels with statistically random noise. This is about making
> sure something bad doesn't happen to your computer like having someone
> transmit blocks of your hard drive out on the network. I assure you
> that Shannon's theorem doesn't speak about that possibility.
Yet, Shannons' tenth theorem can be proven without a hypothesis that
noise is random, or that the signal is anything in particular.
Using intuition, because no formality is really needed, just consider
that the noise is a well-defined sinus function. The error-correcting
channel provides the same sinus function in counter phase. You will
see that the less random the noise is, the easier it gets. Not the
other around.
How about an active adversary? You just need to consider the
adversary's reaction time and make sure that the error-correcting
channel has enough capacity to counter-react within that reaction
time. For chip fabrication, this may be quite long.
Cheers,
Ed Gerck
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