Remote Programming via SSH

Question

Your Article on Telneting with C# was very helpful. I was able to connect to a Unix Server and run scripts from my ASP Application. My requirements have changed and now I must run the same scripts but use the SSH (22) port, using a public key. I have the public key from the Unix Server, but can you tell me how I can login passing the public key without having to purchase a third party control (I have seen a lot of those)? Thanks