Allow signed keys

[robertkentish]

PR as per issue #479. PRoposal to support public certs for RSA signatures as in the following manner.

var keyFile = new PrivateKeyFile(@"C:\temp\ssh_keys\id_rsa", "xxxx"); var certFile = new PublicKeyCertFile(@"C:\temp\ssh_keys\id_rsa-cert.pub"); var authMethod = new PrivateKeyCertAuthenticationMethod("user", keyFile, certFile); var connectionInfo = new ConnectionInfo("192.168.1.1", "user", authMethod);

using (var client = new SshClient(connectionInfo)) { client.Connect(); }

[drieseng]

@robertkentish I did an initial sweep of your changes. Still need to dive a little deeper though. I wonder if - when complete - we should consider shipping this as a separate package (under the SSH.NET unbrella, or not).

[WojciechNagorski]

@robertkentish PR needs refreshing.