RNG White Noise Tests

aesofb_spectrograph-web

aesofb_spectrum

For the upcoming White Noise Boutique, I’ll be generating bespoke white noise for visitors using a variety of methods. These quick tests show that, while they sound essentially the same, different algorithms do in fact generate different white noise. For each generator, a spectrogram and frequency plot are shown for a ten-second sample. The plots were generated with Audacity.

Above: the AES_OFB algorithm from the Dieharder suite, one of two cryptographically-secure methods.

congruential_spectrograph-web

congruential_spectrum

Linear congruential generator, an old-fashioned and non-secure generator.

devrandom_spectrograph-web

devrandom_spectrum

The only “true” generator here, via the operating system’s built-in “dev/random” command, which creates random numbers from hard drive entropy.

threefish_spectrograph-web

threefish_spectrum

The Threefish generator, also via the Dieharder suite and the other cryptographically-secure algorithm.

Racal MA-4204 Time Division Voice Scrambler

RacalMA-4204TimeDivisionVoiceScrambler

Another device using random acoustic noise for cryptographic purposes. This device from the early 1970s randomly rearranges the audio signal every half-second; a corresponding unit puts the audio back in the correct order on the other end. While not very secure (the three 8-position switches only provide 512 possible combinations), this device’s operation and style have a nice mix of of functionality and poetics.

Via Cryptography Museum.

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