Cloudflare uses lava lamps as a random number generator

antonvs 8 years ago |

I'm now looking forward to a future article from security researchers:

"Prediction of a random stream from a lava lamp model constructed from entropic data inferred from encrypted packets"

Chaebixi 8 years ago |

So they created a giant side-channel by putting their entropy-source next to a public window?

CorvusCrypto 8 years ago | |

I'm guessing they use this alongside CSPRNGs. Would make sense given the theorem that states any random number XORed with even highly-ordered input maintains its entropy.

londons_explore 8 years ago | | |

There are lots of people in the crypto world who have serious issues with XORing random sources together.

I haven't yet seen a good argument why it's a bad idea, and part of me thinks it might be a way to get more software using "rdrand" or other insecure sources unmodified.

CorvusCrypto 8 years ago | | |

I think the bad idea stigma stems from people XORing from the same source. That totally is a bad idea, but if two sources are wholly independent, the maximum entropy in the combined systems is maintained.

To the people that just say it's never a good idea and scoff at any reasoning I'd remind them about OTPs. They are a special case related to this principle of XORing two independent sources together where only one input is random and it is proven mathematically to work.

CodeWriter23 8 years ago | |

Pretty sure an attacker would have to observe the array from the same point of perspective as the camera to mount a successful side channel attack.

serf 8 years ago | |

don't forget the room heating. I'm sure a wall of of 25-100w incandescents can get pretty toasty.

very green.

ScottBurson 8 years ago |

I would use plasma spheres (e.g. [0], but there are lots of them out there). A single plasma sphere generates a visual display that changes much faster and is much less predictable moment-to-moment than a lava lamp -- so you wouldn't need nearly so many of them -- and uses much less power into the bargain.

[0] https://www.scientificsonline.com/product/nebula-plasma-ball

wellboy 8 years ago |

Is this a perfect rng at the current state of technology? If not, why and are there currently perfect ones. What would an rng require to be perfect?

jmcguckin 8 years ago |

Nothing new here, move along.

This was first done by SGI ages ago...

joe

joezydeco 8 years ago | |

Article+Cloudflare acknowledges this (although they credit Sun not SGI)