Lotteries, accidents and rolls of dice — the world around us is full of unpredictable events. Yet generating a truly random series of numbers for encryption has remained a surprisingly difficult task.

RANDOMNESS IS A valuable commodity. Computer models of complex systems ranging from the weather to the stockmarket are voracious consumers of random numbers. Cryptography, too, relies heavily on ...

Although schemes to generate random-looking numbers are easy to come up with, assessing their security — the extent to which they are truly unpredictable to a potential adversary — is notoriously ...