[Cryptography] The ultimate random source

Joseph Ashwood ashwood at msn.com
Fri Feb 21 07:52:13 EST 2014

-----Original Message----- 
From: Bill Frantz
Subject: Re: [Cryptography] The ultimate random source

> I feel better with a real image that can test that the camera is still 
> working.

Just make sure there is absolutely 0 post-processing that destroys entropy, 
this is a lot harder than it sounds. This is exactly why I spent so much of 
my initial email about the debayering/demosaicing process, the popular 
processes destroy a significant amount of the entropy. I know it may seem 
irrelevant at first, but any system that starts by throwing away 2/3 of the 
data in a deterministic process, and then proceeds to process the remaining 
data to smooth out any strange bumps throws away most of the entropy.

> We get 6 ** 600 possibilities and we haven't even considered small changes 
> in position of each M&M. 6**600 overflows my HP15 calculator and makes me 
> feel comfortable seeding a PRNG.

Certainly the 6^600 starting states sounds like a lot, but even assuming 
that it is somehow perfect, that is not much more than 1200 bits of entropy. 
Harvesting this 1200 bits of entropy 512 bits at a time is only 2 full 
samples. This is why the continued introduction of entropy matters, and why 
the general lack of entropy introduction matters even more.

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