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Strength of Triple-DES
From: stagda () sys1 ic ncs com (Dave Stagner)
Date: Thu, 13 Apr 1995 13:01:34 -0500 (CDT)


As I understand it, triple-DES is not simply "three times stronger"
than regular DES, but actually an order of magnitude stronger.  Rather
than encrypting three times, you encrypt, decrypt, and encrypt again
with different keys.  And trying to decrypt garbage is far more
difficult than decrypting plaintext.  

I realize that the primary method of crack is guessing weak passwords,
but it also attempts to decrypt.  And given the weakness of
single-DES, it isn't that hard.  So anything that improves
cryptographic strength is good.  Also, it reduces the harm caused by
weak passwords, and adds value to strong passwords.  

I also realize that the ideal solution would be to eliminate fixed
passwords and replace them with some sort of double-blind,
smart-client scheme.  But it won't work, not as long as we're
dependent on existing clients like telnet and ftp working.  I'd say
that we're pretty much stuck with the current methodology as long as
we're stuck with unix and the Internet.  That leaves improving the
existing scheme as our best hope.  If you have any *feasable*
solutions, I'd be very interested.
-- 
* David Faron Stagner
* National Computer Systems           david_stagner () ic ncs com
* 2510 N Dodge St                     vox 319 354 9200 ext 6884
* Iowa City, IA 52244                 fax 319 339 6555
I disclaim my employer and I'm sure they'd disclaim me too.

(This .sig has been sanitized for your protection)



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