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To all the people saying high quality random numbers are not important for crypto, there have been a number of important failures over the years due to semi-pre

To all the people saying high quality random numbers are not important for crypto, there have been a number of important failures over the years due to semi-predictable keys. And there is no way to generate randomness in software, while quantum sources can be provably random. It just makes the crypto system easier to reason about.

pvg 9y ago
None of these failures have been due to a computer's inability to generate sufficiently random numbers so this particular thing is not solving any kind of practical cryptographic problem.
dsacco 9y ago
No one is saying high quality random numbers are not important for cryptography. We are saying true randomness is unimportant and undesirable, given the comparatively enormous complexity required to achieve it. The modern conception of cryptography is explicitly that you do not need "true" anything - randomness, security, indistinguishability, unforgeability, etc. Everything is modeled in game semantics with a computational cost:benefit analysis for attackers. Cryptographic failures with respect to entropy sources occur not because they aren't random enough, but because they're implemented incorrectly. When they're implemented correctly, they're fine, because this is a well studied problem for which we have a variety of useful solutions. This is why proposing a replacement source of entropy using quantum computers is ridiculous, because you would commensurately increase the complexity of the system into completely unknown territory. This isn't exactly a controversial perspective. I don't know of a single reputable cryptographer who takes quantum cryptography seriously. I would be happy to learn of a few, but if you look at the research landscape you'll quickly see that proposals for quantum cryptography are disconnected from the academic cryptography community.

pvg 9y ago

None of these failures have been due to a computer's inability to generate sufficiently random numbers so this particular thing is not solving any kind of practical cryptographic problem.

dsacco 9y ago

No one is saying high quality random numbers are not important for cryptography. We are saying true randomness is unimportant and undesirable, given the comparatively enormous complexity required to achieve it. The modern conception of cryptography is explicitly that you do not need "true" anything - randomness, security, indistinguishability, unforgeability, etc. Everything is modeled in game semantics with a computational cost:benefit analysis for attackers. Cryptographic failures with respect to entropy sources occur not because they aren't random enough, but because they're implemented incorrectly. When they're implemented correctly, they're fine, because this is a well studied problem for which we have a variety of useful solutions. This is why proposing a replacement source of entropy using quantum computers is ridiculous, because you would commensurately increase the complexity of the system into completely unknown territory. This isn't exactly a controversial perspective. I don't know of a single reputable cryptographer who takes quantum cryptography seriously. I would be happy to learn of a few, but if you look at the research landscape you'll quickly see that proposals for quantum cryptography are disconnected from the academic cryptography community.