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Comment by xor99 | Hacker News Reader

I would recommend looking at David Johnston's book "Random Number Generators, Principles and Practices" to get a handle on how complicated evaluating RNGs properly is. Radioactive sources combined with conventional circuits/electronics are too slow for practical applications afaik (e.g. incredibly time consuming to prove the performance but not bad in principle). However, I love the banana idea for its inventiveness.

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For broadband white-noise I really like to utilize the avalanche breakdown noise which you can get from reverse biased zener diodes.

I didn't use it for TRNG but for measurement and it really gives you a nice straight noise spectrum from 10Hz to above 100kHz.

Things that could be relevant for TRNGs: http://www.reallyreallyrandom.com/zener/why-its-random/

Definitely a slow method! It outputs about 1 byte every second. Not great performance! This 22KB sample took several hours to collect: https://github.com/valerionew/Banana-Random-Number-Generator...

Wouldn't it be possible to build large detectors of reasonable cost and power consumption? For example, instead of a small tube like in the article, flat metal plates or arrays of long wires in a thin rectangular chamber.

The throughput is given by the frequency of the radioactive events. This can easily made bigger with a more radioactive source. The limit in this is how fast is the underlying reference timer. If you could have a fast enough timer, you could raise the radioactivity of the source and get a bigger throughput.

I wouldn't be comfortable putting the kind of strong radiation source that can increase events by some orders of magnitude close to me or my computers. Large detectors or multiple detectors to catch more natural radiation are safer.

Yep but the main point that i was trying to make is that to get a faster generator you need a faster clock and a bigger timer, not a bigger detector nor more events, if you cannot back them up with the faster clock and bigger timer

> Radioactive sources combined with conventional circuits/electronics are too slow

That’s the case with bananas, but would a lump of weapons-grade uranium provide enough randomness to be useful?

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