3DES key generation

Johan Wevers johanw@vulcan.xs4all.nl
Fri Apr 18 21:08:38 2003

Egon Andersen wrote:

> And you are right 3DES uses 3*56 bit, but the receiver actually only 
> uses 2DES

Hmmm. I remember there was some big weakness in 2DES, but I can't remember
what it was exactly. Does someone here know that?

> (2*56 bit = 112) packed into a hex-representation of 32 
> characters - therefore I happened to write 128 (= 4 x 32).
> (Actually 48 characters, but the 16 trailing bytes are spaces)

Then the receiver uses it in a different mode than gpg does. Are you sure
both ptograms are otherwise compatible? GnuPG doesn't just output encrypted
data, it stores them in a file format that includes headers, checksums, etc.

> If I could, I would of course like the receiver to use gpg, but they 
> don't, and I don't think I can make them change their system over night.
> (If is a company making most of the bank-transactions in Denmark!!!)

Perhaps the easiest solution would be if you used their cryptosystem?

ir. J.C.A. Wevers         //  Physics and science fiction site:
johanw@vulcan.xs4all.nl   //  http://www.xs4all.nl/~johanw/index.html
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