Re: crypto(4) and IVs

[der Mouse <mouse%Rodents.Montreal.QC.CA@localhost>]

>> In passing, I have to wonder whether you were just being careless
>> with language when you wrote "predictable".
> I meant "predictable by the attacker".  The attacker who sees packet
> N could predict the IV used by packet N+1.

How is this different from seeing block B and thus knowing the IV for
block B+1 within a packet?

If you posit attacker control over the plaintext in packet N+1, you're
talking the adaptive chosen plaintext threat model I mentioned.  If
not, I can't see any significant difference between this and *any* use
of CBC modes.

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