Re: Size of IV field in DES-CBC mode

["Perry E. Metzger" <perry@imsi.com>]

Phil Karn says:
> Do we really need a full 8 bytes for the IV field in the baseline
> DES-CBC mode?

Well, if you are on a gigabit network, you would run through all
possibilities for only 32 bits of IV very, very fast. Of course, DES
is likely a foolish choice for encrypting any serious traffic, anyway,
but for 3DES it makes sense to have a reasonable sized IV.

Myself, I'd say this should be handled by having a different transform
that handles smaller IVs -- or at least, even if the DES case uses
small IVs the 3DES case should not by default.

Perry

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Follow-Ups:

• Re: Size of IV field in DES-CBC mode
• From: Phil Karn <karn@unix.ka9q.ampr.org>

References:

• Size of IV field in DES-CBC mode
• From: Phil Karn <karn@unix.ka9q.ampr.org>

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