[Cryptography] reality +- mathematical guarantees
Sampo Syreeni
decoy at iki.fi
Tue Jun 9 00:30:52 EDT 2015
On 2015-06-08, John Denker wrote:
> In the real world, there are no "hard" guarantees, not for any form of
> error correction ... nor for anything else. Specifically: There are
> lots of ways in which a channel can fail that will not reliably be
> detected using CRC32.
True, but the error floor by S/N is flatter. That's why they did all of
that linear and modulo coding work in the first place, instead of just
randomizing the fuck out of it, per Shannon's original proof.
> Sure, one can create /mathematical models/ for which such-and-such
> method provides a hard guarantee ... but more generally we would do
> well to remember the dictum:
>
> "Insofar as the propositions of mathematics refer to reality, they
> are not certain; and insofar they are certain, they do not refer to
> reality"
>
> -- Albert Einstein
> "Geometrie und Erfahrung" (1921)
"This is the conclusion of the theorem."
-- Claude E. Shannon
"Coding Theorems for a Discrete Source With
a Fidelity Criterion" (1959)
--
Sampo Syreeni, aka decoy - decoy at iki.fi, http://decoy.iki.fi/front
+358-40-3255353, 025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2
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