Swiss physicists turn Nokia N9 into a quantum random number generator

    In the field of computer security, the use of a random number generator (RNG) is the basis for creating any cryptographic system. For example, RNGs are used to protect personal data when processing credit card transactions made over the Internet. Although, not for you to explain to us.



    Interesting news from the development of random number generators came recently from Switzerland: physicists from the University of Geneva found a way to get random numbers using the principle of quantum uncertainty when processing the signal from the sensor of a Nokia N9 digital camera.
    Let's try to figure out what's wrong with that.

    Speaking about the state of affairs in the field of cryptography at the moment, it can be noted that quite a lot of ways have been invented recently for obtaining random and pseudorandom numbers from various sources.

    However, it is important not only to create a number generation system, but to make it such that it is not a weak link in the protection of the cryptographic system (systems with pseudo-random cycles can be cracked by intruders). This is a rather nontrivial task that cannot be solved by purely programmatic means, since some kind of analog stream must be present from outside the system.

    The best solution in this case is the use of a quantum random number generator, making it impossible to predict the generation of random loops.



    The principle of operation of such an RNG is based on the analysis (calculation) of photon emission. This quantum process is random in nature, since a random number of photons are produced from a light source at a specific time interval.

    Despite the fact that this method is usually quite expensive and complicated, Swiss students seem to have found a budget solution based on the Nokia N9 smartphone.

    The authors of the scientific work note that the photosensitive sensors of modern smartphones have reached high quality and are able to take into account quantum effects of this kind.

    Each pixel in the Nokia N9 8MP sensor in the prototype created by students can determine the number of photons for a certain period of time, and then convert them into a series of random numbers.



    After a series of tests, where the green LED, which uniformly illuminates all the pixels in the sensor, acted as a light source, it was possible to calculate the performance of this system. The result was random numbers in a 1 megabit / s stream. Of course, this is far from a record for RNG systems, but this is more than enough for reliable cryptographic encryption of applications for mobile devices. It was also revealed during the experiment that the Nokia N9-based generator gives only one deviation from the ideal random sequence at 1096 iterations.


    Comparison of measurements of quantum and classical noise with a specialized ATIK 383L detector (top) and Nokia N9 smartphone (bottom).

    For more details on this project, see the published study here.

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