Subject: Re: crypto(4) and IVs
To: None <>
From: der Mouse <mouse@Rodents.Montreal.QC.CA>
List: tech-crypto
Date: 05/29/2005 14:43:34
>> 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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