Reply-To: jvncnet!the-tech.mit.edu!jeremy
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>>>>> "Rex" == Rex Ballard  writes:

  Rex> The algorythm for DES has been public for years.  The security
  Rex> is still quite adaquate even using 64 bit keys.

DES has been a standard for 15 years. I think it is rather secure, but
there are some important things to keep in mind. First, it is really a
56-bit key with 8 bits of parity. Second, the algorithm is public, but
the design decisions that led to the particular algorithm being chosen
is classified; there is a non-linear permutation that occurs during
DES encryption and the NSA has declined to explain what its purpose
is. 

Theoretically someone with a few million could build a DES-cracking
machine. I don't expect there is anyway to know if someone has, but
it's hardly outside the realm of possibility. 

  Rex> I've often suspected that the main reason for keeping RSA
  Rex> secret is that it would be discovered that there was little
  Rex> technical superiority of RSA over DES.

I'm confused by this, though. The RSA algorithm is well understood and
documented in full. There have been numerous academic papers on it and
many cryptographers have tried to crack it.

The security of RSA is based on the difficulty of factoring really big
prime numbers, not on some secret.

BTW, if you're interested Bruce Schneier has written a great, if
somewhat technical book, called Applied Cryptography.

Jeremy

From jvncnet!marketplace.com!owner-online-news Mon Oct 24 13:29:31 1994