[Cryptography] reality +- mathematical guarantees

[John Denker]

On 06/08/2015 11:12 AM, Sampo Syreeni wrote:

> Of course you do have a stochastic guarantee, with md5sum, but no
> hard one like you do with CRC32.

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.

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)