Free end-to-end encryption code?

[willer@carolian.com (Steve Willer)]

As a side project, to support remote mail and news pickup through the
Internet to my company's servers (through a firewall), I've been
slowly writing an end-to-end encryption program. Essentially, the idea
is that the client program (say, a mail program) connects to a client
"reflector", which lives on the same person's machine. The client
reflector connects to a server reflector, which perhaps lives on the
firewall. The client and server talk to each other, the client is
authenticated, and the session key is agreed upon. Then the server
reflector connects to the server process (say, smtpd, probably on some
machine inside the company's net), and an encypted session is
obtained. This doesn't protect against the machine's memory being
watched or anything like that, but it does provide a good amount of
security for packets over the Internet, just like the end-to-end type
of encryption software described in Applied Cryptography.

Now, this is my first code with any real encryption in it, and I'm
trying to tackle key negotiation protocols and so on, while at the
same time utilizing RSA, IDEA and MD5. In my research, I found that a
number of firewall vendors have such a system available, either
implemented in hardware or software. What I want to know is: Is there
any code like this available somewhere on the net that does this
stuff? I would hate to have to reinvent the wheel if I don't have to,
given my limited amount of spare time.