Brute Force DES

Adam Shostack adam at homeport.org
Wed Jul 24 08:11:15 PDT 1996


	Most protocols give you stereotyped headers, which are
perfectly valid for known plaintext attacks.  The rc4 cracks were done
on the Netscape rc4(md5(key+salt) used in ssl.  They were based on
known plaintext in the HTTP headers.

	(Incidentally, we might want to test the key distribution &
reporting mechanisms on a crack of vanilla rc4-40, or another SSL
crack.  Cracking des will not be cheap, and we should do some test
runs first.)

Adam

The Deviant wrote:

| > For instance if you had a DES encrypted gzipped file. The first 2 bytes
| > plaintext will be Ox1f8b. You'd only have to try to fully decrypt

| Buy the point is to prove that DES shouldn't be used, not that it CAN
| be brute forced.  A known-plaintext attack doesn't show that.  We hafta
| attack something we've never seen. (i.e. talk Netscape, or some other
| company, into generating a DES'd message, and keeping the keys safe)


-- 
"It is seldom that liberty of any kind is lost all at once."
					               -Hume







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