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Perseidstoday at 7:32 AM1 replyview on HN

Super important: Don't replace traditional (elliptic curve) Diffie-Hellman with ML-KEM, but enhance it by using hybrid key exchanges. Done thusly, you need to break both the classical and post-quantum cryptography to launch an attack.

If you worry about a >=1% risk of quantum attacks being available soon, you should also worry about a >=1% risk of the relatively new ML-KEM being broken soon. The risk profile is pretty comparable. For both cases there are credible expert opinions that say the risk is incredibly overrated and credible expert opinions that say the risk is incredible underrated.

Filippo has linked opinions that quantum attacks are right around the corner. People like Dan Bernstein (djb) are throwing all their weight to stress that anything but hybrids are irresponsible. I don't think there is anybody that says "hybrids are a bad idea", just people that want to make it easy to choose non-hybrid ML-KEM.


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pie_flavortoday at 11:25 AM

How do you mean the risk profile is comparable, when ECDH is nearly guaranteed to be broken in five years and Kyber is two decades old? The two have nothing to do with each other, the ECDH component of a hybrid becomes worthless before you next replace your smartphone, and bloating the protocol can only hurt adoption. Yes, djb keeps making the same crankish complaint without any evidence or reason, that doesn't mean you have to repeat it uncritically.

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