Re: Initial entropy with no HWRNG

Mouse <[email protected]> Tue, 12 May 2020 13:05:01 -0400 (EDT)
Newsgroups gmane.os.netbsd.devel.crypto
Message-ID <[email protected]>
>> B1) Because they already got the binaries or the sources from us; we
>> could simply tamper those to do the wrong thing instead.
> Tampering is loud, but eavesdropping is quiet.  There is no way to do
> this that is resistant to eavesdropping without a secret on the
> client side.

Ironically, there is, from an algorithms perspective, the simplest
perhaps being Diffie-Hellmann.  (D-H is as hard as discrete log, for
passive eavesdroppers.  It's active MitM that it's not enough for.)
The irony arises because, as far as I know, all such algorithms require
randomness - or at least unpredictability to the attacker - on each
end, making this a chicken-and-egg problem.

Or is that what you meant by "a secret"?

(Admittedly, well-done MitM is quiet too, if you don't have some kind
of identity verification rolled into the exchange.)

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