From: henry strickland <strick@osc.versant.com>
Date: Wed, 24 Nov 93 10:58:18 PST
To: sameer@uclink.berkeley.edu
Subject: Re: <8c> C-source for diffie-hellman?
In-Reply-To: <m0p15mc-000J6eC@infinity.hip.berkeley.edu>
Message-ID: <9311241857.AA24005@osc.versant.com>
MIME-Version: 1.0
Content-Type: text/plain


# 	I was just talking with a friend, and I think it would be
# pretty good for medium-level security on irc to hack up something do
# that /dcc does diffie-hellman key exchange, and maybe triple-des or
# something.
# 	Is there some available C-source which would help? (I guess I
# should get the Schneier book.. But urgh! $50 on a "starving-student"
# budget is quite a bit.)

DH itself is a trivial algorithm.  All you need is a decent
multiple precsion math package.    I think all it takes is
	-- random numbers
	-- primality test
	-- gcd
	-- raise-to-power-modulo-some-number

There's lots of Multiple Precision libraries availble.
The Gnu 'gmp' is more than sufficient.  Also des is very
easy to ftp.  See the cypherpunks ftp site at 
	ftp://soda.berkeley.edu/pub/cypherpunks/
for pointers.

					strick


BTW, schneier is literally a FAQ for cypherpunks.  
Fantastic book.  Cough up the money for it...