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Google's threat model for post-quantum cryptography

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Re: Google's threat model for post-quantum cryptography

#5
Stateless tokens come with independent security concerns, and moving towards stateful tokens is prudent just to ensure more robust systems. [...] Our main recommendation is to use stateful tokens where possible, given their additional security benefits.

This is smart. PQC schemes often add too much overhead for interoperable cookie sizes. Instead of trying to cram a PQC signature into a cookie, just stop using the stateless cookie designs that require asymmetric signatures.

I'm not sure I buy the Global Risk Institute chart. I get that they need to motivate adoption, but practical cryptanalytic work with quantum computers seems unpromising right now.

Re: Google's threat model for post-quantum cryptography

#9
post #5

Stateless tokens come with independent security concerns, and moving towards stateful tokens is prudent just to ensure more robust systems. [...] Our main recommendation is to use stateful tokens where possible, given their additional security benefits. This is smart. PQC schemes often add too much overhead for interoperable cookie sizes. Instead of trying to cram a PQC signature into a cookie, just stop using the st…

[deleted]

Re: Google's threat model for post-quantum cryptography

#10
post #8

This may be a naive question but why not go back to Vernam? Storage is cheap.

OTP is deeply impractical.

How do you distribute your pads? (hint: it's a chicken-and-egg problem, you need a secure channel)

How do you ensure they're only ever used once?

In its most obvious instantiation, you get no authentication. So now you have to build an authentication mechanism on top. There's simply no point, when we have better solutions already.

And to top it all off, symmetric ciphers aren't threatened by quantum computing in the first place.

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