Re: Mac encryption

[tcmay@netcom.com (Timothy C. May)]

Ron Davis writes:

(quoting me)

> >MacPGP, available by anonymous ftp from the soda.berkeley.edu site, is
> >the only one I know of using public key methods, and hence the only
> >one of real interest to Cypherpunks.
> 
>         I find this to be a strange statement.  Do we have no interest
>         in non-public key methods?  Seems the Cypherpunks should have
>         an interest in all forms of crypto.  Most users don't currently
>         use public key becuase they just want to keep thier boss from
>         sitting down at thier computer and reading the resumes they wrote
>         for other companies.  This can be accomplished with symetrical
>         crypto just as well, if not faster than PGP.

The problem with symmetrical ciphers is one of *scaling*.

Since a key must be exchanged with each other person, the total number
of keys growns rapidly as the community of participants increases. At
any stage, the key may be lost, stolen, observed, shared with the
Feds, etc. A community of 700 participants, as here on Cypherpunks,
would mean each person would have to generate, exchange (securely!),
and store 700 specific keys for use just with others.

This is the famed "key distribution problem."

With public key methods, this problem is largely solved. Each person
can generate his or her own key, publish the public key part of it,
and be done with it.

More than just for secure 2-way communications, this opens the door
for all the other applications Cypherpunks are so interested in.
Symmetric ciphers likek DES or IDEA just don't offer that richness.

(Symmetric ciphers are of course often embedded in public key
protocols, as with using RSA to protect DES session keys. In this
case, the cumbersome problems of key distribution are avoided, and the
speed advantages of symmetric ciphers are obtained.)

I haven't said Cypherpunks should avoid symmetric ciphers, just that
they produce little of the revolution in communication and commerce
that interests us so much.

--Tim May


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