您的问题是您仍在使用密码，即使它是空白的.删除这一行:

Your problem here is that you're still using a password, even though it is blank. Remove this line:

new PasswordAuthenticationMethod(username, ""), 

这对我来说非常有效:

var pk = new PrivateKeyFile(yourkey);
var keyFiles = new[] { pk };

var methods = new List<AuthenticationMethod>();
methods.Add(new PrivateKeyAuthenticationMethod(UserName, keyFiles));

var con = new ConnectionInfo(HostName, Port, UserName, methods.ToArray());