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Re: ESP with stream ciphers
Norman Shulman says:
> On Tue, 15 Apr 1997, Rodney Thayer wrote:
> > We need 8 byte IV's for DES and 3DES, right? Not 24 bytes for 3DES?
>
> DES requires a 64 bit IV, but for ESP a 32 bit folded IV is often transmitted.
> Early 3DES drafts require a 64 bit IV (outer, not inner).
3DES is secure only if used as a black-box engine (see Biham's paper).
That means - no inner feedbacks. That in turn means - only one IV for
the first DES is needed. It has to be 64 bits, and it can be folded
for transmission to 32 bits, just like the good ESP draft says.
--
Regards,
Uri uri@watson.ibm.com
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