[Haskell-cafe] Re: True Random Numbers

Yitzchak Gale gale at sefer.org
Thu Apr 15 07:03:37 EDT 2010

Since they weren't mentioned in this thread, I'll point
out that there are better sources of entropy than
/dev/random, /dev/urandom, and the Windows API.

For example, the two sites


both offer free random bits via a secure REST interface.

Random.org is run by Mads Haahr of the School of
Computer Science and Statistics at Trinity College, Dublin.
They use background atmospheric radio noise to
generate the entropy.

Fourmilab is run by John Walker. He uses a source of
radioactive decay (Ce 137) and a geiger counter to
generate the entropy.

Both sites have gone to some trouble in design and
testing to ensure that their entropy is truly random.

There are quotas on the number of bits you can retrieve
per day for free at each of the sites. At random.org, you
can purchase additional entropy at low cost.


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