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RE: telnet vs ssh on Core equipment , looking for reasons why ?


From: Roeland Meyer <rmeyer () mhsc com>
Date: Tue, 31 Jul 2001 16:16:24 -0700


From: Valdis.Kletnieks () vt edu [mailto:Valdis.Kletnieks () vt edu]
Sent: Tuesday, July 31, 2001 3:10 PM

On Tue, 31 Jul 2001 14:59:25 PDT, Roeland Meyer said:

You are probably aware, but EFF published the DES crack. I 
understand that
it is  now an issue of cracking DES in less than 12 hours. 
3DES is better
but it only amounts to DES with a 128-bit key.

Actually, 3DES has a 112 bit effective key.  However, 
although that's only
double the key length, the *difficulty* is a bit more than 
twice as much.
Assuming a brute-force of a 56-bit key in 12 hours, then a 112 bit key
will take (given the same resources) 2**56 * 12 hours, which is about
864,691,128,455,135,232 hours which works out to 
98,709,032,928,668 years,
which is about 4,000 times the current estimated age of the universe.

This analysis of course assumes that the EFF crack is a brute-force,
and not a result of differential cryptanalysis or exploitation of a
flaw in the DES S-boxes or similar.  Schneier's 'Applied Cryptography'
lists an attack that's around 2**47 rather than 2**56, 
assuming you can
get the victim to encrypt several gigabytes of text of your 
choosing with
his key....

 ... and then they load it on www.distributed.net


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