What is the most secure seed for random number generation?

Question

What are the most secure sources of entropy to seed a random number generator? This question is language and platform independent and applies to any machine on a network.

Answer 1

As an interesting take on one-time pads, whenever I'm engaged in espionage I have a system whereby I need only communicate a few letters. For example, the last time I was selling secret plans to build toasters to the Duchy of Grand Fenwick, I only needed to whisper:

enonH

to my confederate. She knew to get http://is.gd/enonH- (this is a "safe" expander URL which takes you to the is.gd expansion page which in turn points to a completely SFW image of a frog). This gave us 409k bits of one-time pad or - if I wink while whispering "enonH" - she knows to take the hash of the image and use that as a decoding key for my next transmission.

Because of the compression in JPEG images they tend to be relatively good sources of entropy as reported by ent:

$ ent frog.jpg
Entropy = 7.955028 bits per byte.

Optimum compression would reduce the size of this 51092 byte file by 0 percent.

Chi square distribution for 51092 samples is 4409.15, and randomly would exceed this value 0.01 percent of the times.

Arithmetic mean value of data bytes is 129.0884 (127.5 = random).
Monte Carlo value for Pi is 3.053435115 (error 2.81 percent).
Serial correlation coefficient is 0.052738 (totally uncorrelated = 0.0).uncorrelated = 0.0).

Combine that with the nearly impossible to guess image that I directed her to and my secret toaster plans are safe from The Man.