symmetric encryption broken

Matthias Urlichs smurf at noris.de
Fri Mar 9 22:14:08 CET 2001


Hi,

Michael H. Warfield:
> 	Huh...  Wait a minute.  You're encrypting it once and then
> encrypting it a second time.  What are you trying to accomplish here?
> 
Some ciphers are symmetric. If you DES-encrypt something, and then "encrypt"
the ciphertext again, you magically get the plaintext back.

The same thing works with any cipher algorithm which computes a secure
hash and XORs it with the plaintext. (You could use MD5 as a cipher that
way.)

-- 
Matthias Urlichs     |     noris network AG     |     http://smurf.noris.de/



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