An App For That...

Source: Physics World link below

...or, at least, there soon will be.

Do you feel nervous when you make a credit-card transaction using your mobile phone? Your worries could soon be a thing of the past, thanks to a low-cost device that could bring powerful cryptography to portable devices. That's the aim of Bruno Sanguinetti and colleagues at the University of Geneva in Switzerland, who have created a quantum random-number generator (QRNG) that uses low-cost electronic components including a mobile-phone camera.

Modern cryptographic protocols require the rapid generation of sequences of truly random numbers. These are used to create the "keys" that allow individuals to encrypt and decrypt sensitive information such as passwords and bank details. Coming up with these numbers is a significant technological challenge because computers are completely deterministic and are therefore not capable of creating truly random numbers. Cryptography systems tend to rely on "pseudo random-number" generators that output sequences of numbers that are nearly random. While some of these generators are very good, a cryptography system based on pseudo random numbers is easier to hack than a system that uses random numbers.

Truly random numbers can be generated by making measurements on physical systems that are inherently random – such as the radioactive decay of nuclei or noise in an electronic circuit. However, existing measurement techniques tend to be either very expensive or too slow to be of practical use. Securing your mobile phone, for example, needs a generation rate of about 1 kbit/s.

Physics World:
How to make a quantum random-number generator from a mobile phone, Hamish Johnston