LinuxSA Mailing list archives

  From: Mark Newton <newton@atdot.dotat.org>
  To  : behoffski <behoffski@grouse.com.au>
  Date: Tue, 14 Sep 1999 22:38:00 +0930 (CST)

Re: Encryption (was Re: Linux Console Security)

behoffski wrote:

 > Note that the level of encryption needed to keep people out 
 > is increasing all the time, as decryption machines become 
 > cheaper and people discover new attacks.  NIST is working 
 > through a process of selecting a new crypto scheme at the 
 > moment, called AES (Advanced Encryption Standard).  Many of 
 > these encryption schemes have 256-bit keys. 

The days of the inadequacy of 256-bit keys for long-term protection
of data are fast approaching.  If NIST is pushing 256-bit keys, you
can bet your bottom dollar that that means the NSA is capable of
cracking 256-bit crypto in a reasonably short amount of time. :-)

The strength of crypto that should be used is a function of the 
value of the data you're protecting and the length of time you need
to protect it for.  If you need to keep a contract worth $100,000
secret for a 14-day cooling-off period, don't use an algorithm that
can be cracked in 13 days by a machine that costs $99,999.  As the
critical length of time increases, the cost of a machine which will
break the key within that time decreases, and vice-versa.  For
reference purposes, the DES cracker built by EFF, "Deep Crack," can
be built for under US$100,000, and can crack a 56 bit DES key in a few
hours.

Are there any rich bastards reading this list? :-)

 > The days of 56-bit DES are long gone, if you're serious about 
 > keeping data hidden.  

Absolutely -- passwords included.  

    - mark

--------------------------------------------------------------------
I tried an internal modem,                    newton@atdot.dotat.org
     but it hurt when I walked.                          Mark Newton
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