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Re: 3DES with 40-bit key?

On Mon, 29 Mar 1999, Dave Perks wrote:
> Is something like http://www.counterpane.com/low-entropy.html an option?
> I quote the abstract w/o permission:
> ABSTRACT: We introduce the notion of key stretching, a mechanism to
> convert short s-bit keys into longer keys...

Fortunately (unfortunately?), the IKE mechanism for IPSEC key negotiation
is completely defined and does not include any such chicanery.  When it
keys 3DES, it does it with 168 bits, not with 40 "stretched" to 168.  You
can't interoperate with it without using an honest 168 bits.

                                                          Henry Spencer

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