Subject: Re: FUD about CGD and GBDE
To: Poul-Henning Kamp <>
From: Perry E. Metzger <>
List: tech-security
Date: 03/03/2005 19:10:16
Thor Lancelot Simon <> writes:
> I think there's a misunderstanding here.  Why do you think secrecy
> (unpredictability?) is an important property of an IV for a block
> cipher used in CBC mode?  It's not an encryption key, it's an IV.

Indeed. The IV can (subject to some constraints) be anything you
like. Not having it public at very, very best denies one block from
the ciphertext to the attacker -- ultimately not very useful in this
application to prevent cracking given the low unicity distance.

Perry E. Metzger