Need C# source code – for connect SFTP server without password option

SessionOptions sessionOptions = new SessionOptions
{
    Protocol = Protocol.Sftp,
    HostName = Dts.Variables["HostName"].Value.ToString(),
    UserName = Dts.Variables["UserNameSFTP"].Value.ToString(),
    PortNumber = Convert.ToInt32(Dts.Variables["PortNumber"].Value),
    SshHostKeyFingerprint = "ssh-rsa ################",                    
    SshPrivateKeyPath = "D:\\WinsSCPkey\\Win_Private4.PPK",
};
using (Session session = new Session())
{
    session.ExecutablePath = Dts.Variables["WinscpExecutable"].Value.ToString();
    session.Open(sessionOptions);
}