Summary: ... Hotbits and Random.org exist mostly as educational diversions. They don't pour out random
numbers fast enough for such voracious demands as ultra high-security cryptography. Several
years ago, Mr. Noll and some colleagues at the Silicon Graphics Corporation began an effort to
make an industrial strength random-number dispenser out of lava lamps (or, as their maker,
Haggerty Enterprises, insists they should be called, "Lava Lite" lamps.)
A lava lamp is a chaotic system, meaning that it is ruled by a phenomenon called "sensitive
dependence on initial conditions." The slightest variations in the temperature, the distribution of
the "lava," and many other variables lead to wildly divergent patterns in the slow, burbling ballet.
Throwing in even more wild cards, Mr. Noll and his cohorts used six lava lamps, each of a
different color. The result was called Lavarand. Every second a digital camera snapped an image
of the fluctuating scene converting the array of pixels into a string of bits.
This stream of ones and zeroes still contained an undesirable amount of predictability. The lava,
after all, had to stay within the confines of the six stationery lamps -- it couldn't go jumping from
one to another. A red lava lamp couldn't randomly turn yellow or blue.
To weed out the pockets of order, the scientists sent the signal through an automatic number
mangler called a hash function -- a kind of distiller of randomness. A tiny fluctuation in the
algorithm's input -- a subtle variation in the brightness or hue of a single pixel -- would cause
the output to wildly fluctuate. The result was a smaller, messier bit string -- call it Essence of
Chaos. Finally these digits were used to seed a heavy-duty pseudorandom generator called a
Blum Blum Shub (after its inventors, the computer scientists Lenore Blum, Manuel Blum and