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Comment by daedalus2027 | Hacker News Reader

daedalus2027

> It may seem bizarre that Cloudflare would allow average people to affect the video footage, but that’s actually intentional. External disturbances like human movement, static, and changes in lighting from the adjacent windows all work together to make the random code even harder to predict.

well what if you show up with a white blanket and putit in front of the camera?

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Unless you could hold the blanket perfectly still and prevent outside light from reflecting off of it, it probably makes zero difference. The cameras don't need large amounts of contrast or even big variances in hue, just small amounts of randomness in the ripples in the fabric you are holding up is enough.

then why would they use so many lava lamps?

Because it looks cool and makes for lots of stories in the media like this one. People have reliably used webcams with the cap on to create entropy suitable for effectively true random numbers.

...it’s a marketing tactic.

fine, black blanket then ?

You’d need like Vantablack or something similar.

Even then, there will be plenty of electrical noise to provide entropy.

Even so, a good RNG will make attempts to verify the quality of the entropy. For example, Intel's RNG will statistically observe bit patterns from their RNG. Eg, it fills up a FIFO and checks for the counts of certain bit patterns. If they aren't sufficiently random, it will throw away the data. Even if they dont have sufficient RNG data, unless you can predict how a PRNG is seeded it should be safe for quite some time without new true entropy.

A key property of cryptography is that a good entropy source XOR'd with a poor (biased) entropy source does not degrade the quality of the final result.

Maybe point a strong laser at the cam instead so its "blinded" and all pixels have max brightness. Or even destroy the sensor with a laser, that way it may permanently produce non-random data.

Low bits make just as much difference to a hash as high bits.

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