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[Reply #15 on:]

- http://www.random.org/integers/ - ?

I'm afraid I don't have an ethernet shield, so that's not an option!

[Reply #16 on:]

If finding enough entropy is the only problem, I'm willing to offer my son's bedroom as a useful source.

[Reply #17 on:]

my son's bedroom

Now there's a source we haven't considered before. Probably the only one left I think.

Note that the Due should finally lay this to rest as the SAM3X has TRNG hardware.

______
Rob

[Reply #18 on:]

Any one who considers arithmetical methods of producing random digits is, of course, in a state of sin - John von Neumann

If you really want better randomness, you pretty much have to get it from some external physical source.

It really depends upon what you are using the 'randomness' for.  For instance simulation techniques do not usually need true randomness--only something that is close.  Something mathematical techniques are usually well suited for.  And there are a few mathematical generators that outperform all but the best of the physical sources. 
Most true sources of entropy; radioactive DECAY; avalanche noise; Johnson noise; clock jiggered; all require deterministic whitening techniques in order to produce unbiased random numbers. And they are very temperamental.  Small changes to their operating environment can severely compromise their performance.

[Reply #19 on:]

ID Quantique makes the Quantis RNG:

http://www.idquantique.com/true-random-number-generator/products-overview.html

which looks pretty good. The USB-4M module costs 990 €.

[Reply #20 on:]

990 €.

I'm nowhere NEAR that desperate.  I don't need it to stand up to an army of statisticians, I just need something more random than what the Arduino can do on its own!  I think the entropy library will work fine.

[Reply #21 on:]

Exploiting quantum mechanics like that is a clever idea, though.

[Reply #22 on:]

Exploiting quantum mechanics like that is a clever idea, though.

But think of all the poor cats.

[Reply #23 on:]

Couldn't you use a tunnel diode to achieve about the same thing?  Of course, they're more expensive than Zeners....

[Reply #24 on:]

Tunnel diodes aren't suitable as noise generators.

[Reply #25 on:]

I just skimmed through the thread, so I don't know if someone mentioned this already. How about trying http://code.google.com/p/tinkerit/wiki/TrueRandom. They claim that it is very random. It uses analog input A0, and some other stuff.

[Reply #26 on:]

I just skimmed through the thread, so I don't know if someone mentioned this already. How about trying http://code.google.com/p/tinkerit/wiki/TrueRandom. They claim that it is very random. It uses analog input A0, and some other stuff.

They claim it is random; however, it fails even the simple tests

Code:

Entropy = 6.440816 bits per byte.
 
Optimum compression would reduce the size
of this 1,002,424 byte file by 19.49%
 
Chi square distribution for 1,002,424 samples is 4802982.71, and randomly
would exceed this value 0.00% percent of the time.
 
Arithetic mean value of data bytes is 100.3535 (127.5 = random)
Serial correlation coefficient is 0.042774 (totally uncorrelated = 0.0).

[Reply #27 on:]

I'm intrigued as to where you got those test results from... whatever you used for it seems like it would be very useful!

[Reply #28 on:]

ent can be downloaded here...
http://www.fourmilab.ch/random/

Just feed it a file of binary data.  Try a few JPGs.

[Reply #29 on:]

As CodingBadly mentioned ent is the source of the test results I posted; however, I made a python script that performed those tests with a few options along with some graphs which I find useful; histogram and scatter.

That python script can be found here; http://code.google.com/p/avr-hardware-random-number-generation/source/browse/analyze.py