Re: DES Question

[Matthew J Ghio <mg5n+@andrew.cmu.edu>]

Phil Karn wrote:

> That sounds like my code.

Yup. :)

> That feature seemed like a good thing to do at the time. Then I
> learned about differential cryptanalysis.

Seven years is a virtual eternity in cyberspace.

> No, you cannot strengthen DES in this way, and in fact you
> could actually weaken it unless you are sure to use 128
> completely random bytes for your key.

Okay...  It would prevent brute-force attacks though, wouldn't it?  It
may not prevent differential cryptanalysis, but it would be difficult to
obtain the large amount of data required for differential cryptanalysis
from just a few encrypted email addresses.  Random numbers aren't really
a problem; I have a RNG running here, continuously generating random
numbers from system usage statistics and incoming email.

P.S. What's KA9Q?