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Can you mess it up? Take your friends phone, point it at a known pattern and send tons of insecure data?

Can you mess it up?

Lay the phone's camera facedown on computer desk. It'll probably be a black picture.

There's still noise in the picture even if it's entirely black, but Whether it's possible to generate secure random numbers via nothing but that noise is an open question.

Apparently you got downvoted because this doesn't answer the question: no data is not insecure data. There is no hardware RNG that guarantees full time availability of unlimited secure data. Even if a black image would generate insecure data, it's easy to detect a black image.

Also saturate the sensor, then you don't get noise.

In my experience even a "saturated" sensor (with light bright enough to cause all pixels to read full-white, but not bright enough to cause damage) will still generate some random noise, although far less of it.

(Ironically, the cheaper the camera the more noise it is likely to have, and thus be better for this application...)

I think it is questionable whether this kind of process can generate true random numbers given a small amount of light. Tests should be conducted in worst case conditions in order to trust the system.

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