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.

Random number sequences are essential to a host of encryption schemes. But true randomness in the strict sense is not possible in the classical world; it only occurs in quantum-mechanical processes.

The static from a old radio is a form of random interference caused by electromagnetic activity in the atmosphere (Credit: Getty Images) Our world runs on randomly generated numbers and without them a ...