This was answered by Jamie Driver within the Jade repo.
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Should you go for new pockets on Jade (ie for Jade to create you a brand new pockets on-board the hw – all the time the most suitable choice!), this perform known as.
As you may see it will get some entropy whose size relies on what number of phrases you need in your restoration phrase (12-words/128bits is often thought of adequate, particularly if paired with a passphrase, however we additionally provide 24-words/256bits).The entropy is obtained by calling get_random() which will get entropy from the interior random machine.
When Jade begins up, the random machine is seeded with preliminary entropy from a lot of sources/sensors on the chip – temperature, battery/usb present/voltages, radio noise and so on. – these surroundings sensors themselves embrace a level of random ‘noise’ in addition to no matter they really pattern. See right here.
Additionally throughout boot the digital camera is activated and a lot of frames of picture information is fed into the random seeding – once more even is jade was mendacity on a desk, the ‘black frames’ captured would include random noise. See the boot up code right here and right here.
Throughout operation, the interior random machine incessantly re-fetches supply entropy from the sensors on the chip – temperature, battery/usb present/voltages, radio noise and so on. as above (however not the digital camera) to feed into the machine. See wherever refeed_entropy() known as.
Moreover at any level the related utility can ship in some entropy which jade additionally throws into its mixture of seed entropy. See right here (Apps would often feed in some entropy after they initially join.)
NOTE: when supply entropy is feed into the machine it’s all the time cumulative/further. We’re all the time ‘including’ some extra seed randomness, not ‘changing’ previous information with new information.