RE: Just how does it know?

Justin Dolske (
Thu, 1 May 1997 11:07:29 -0400 (EDT)

On Thu, 1 May 1997, Scott Lipcon wrote:

> This also brings up a point as to how useful it would be to break DES
> encryption. If I encrypt a message with a 56 bit key, and you have no
> idea what the first 24 characters are, you really have no way of telling
> when you manage to pick the right key.

But you would often have a good idea. If I DES encrypted a text file, the
odds of a key decoding the first block to all text is rather low. If we
just check for alphanumeric characters in the first block or two, that's
probably good enough. A human (or AI program) can sift through the results
to be sure. This would be a little slower, but the net effect is the same.

Justin Dolske <URL:>
Graduate Fellow / Research Associate at The Ohio State University, CIS Dept.
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