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I remember using lava lamps for SSH random number generation from the 90's. However, they may have yielded this entire area of security: So-called "physically

I remember using lava lamps for SSH random number generation from the 90's. However, they may have yielded this entire area of security: So-called "physically unclonable functions" https://en.wikipedia.org/wiki/Physical_unclonable_function https://en.wikipedia.org/wiki/Physical_unclonable_function I am immensely skeptical of these, but they have some academic and other obscure traction.

kennedyjavelin 6y ago
Before anyone else looks into PUFs as a mechanism for generating entropy (like the lava lamps are), they don't. It's kind of the opposite kind of randomness. Lava lamps create new randomness every time whereas a PUF generates the same randomness always.
- motohagiography 6y ago
  The skepticism I have of PUFs is that since they don't generate random numbers, they may just be another open loop unfalsifiable concept in security that reduces to "it's complicated, take my word for it." The relationship to lava lamps is PUFs are a physical instead of a logical source of data, conceptually not unlike a quartz crystal in a clock, or radio active decay for random numbers, or even biometrics for authentication. You take something physically natural then sample it at a given interval to get logical data within certain parameters. The security of such a system is not in the mystery of the physical object, but the sampling scheme. Apropos of the news, just like it isn't important so much who people vote for, it's who counts the votes that matters. The security of both lava lamp RNGs and PUFs are subject to an analogous sampling dynamic. So are biometrics.
numpad0 6y ago
The version of PUF I’ve read about in a decade or so ago was you make a cryptographic chip, except you leave the key field blank, but let manufacturing variances “generate” the key by itself, and mathematically declare that it is so impossibly unlikely that two of its examples end up having the same bit patterns. IIRC major challenges included ensuring and proving randomness, stability of bit patterns over time, and general longevity of the whole chip. The alternative to it is to just generate the key and write it at some point in the chip production line, and that’s generally considered good enough, so...

kennedyjavelin 6y ago

Before anyone else looks into PUFs as a mechanism for generating entropy (like the lava lamps are), they don't. It's kind of the opposite kind of randomness. Lava lamps create new randomness every time whereas a PUF generates the same randomness always.

motohagiography 6y ago
The skepticism I have of PUFs is that since they don't generate random numbers, they may just be another open loop unfalsifiable concept in security that reduces to "it's complicated, take my word for it." The relationship to lava lamps is PUFs are a physical instead of a logical source of data, conceptually not unlike a quartz crystal in a clock, or radio active decay for random numbers, or even biometrics for authentication. You take something physically natural then sample it at a given interval to get logical data within certain parameters. The security of such a system is not in the mystery of the physical object, but the sampling scheme. Apropos of the news, just like it isn't important so much who people vote for, it's who counts the votes that matters. The security of both lava lamp RNGs and PUFs are subject to an analogous sampling dynamic. So are biometrics.

numpad0 6y ago

The version of PUF I’ve read about in a decade or so ago was you make a cryptographic chip, except you leave the key field blank, but let manufacturing variances “generate” the key by itself, and mathematically declare that it is so impossibly unlikely that two of its examples end up having the same bit patterns. IIRC major challenges included ensuring and proving randomness, stability of bit patterns over time, and general longevity of the whole chip. The alternative to it is to just generate the key and write it at some point in the chip production line, and that’s generally considered good enough, so...