Hi Mathias,
Thank you for your feedback!
There is C library implementation already available:  newbielink:https://www.libssh.org/ [nonactive] with following features:
    SCP and SFTP support (client and server)
    Support for Linux, BSD, Solaris and Windows
    Client and Server implementation
    Kerberos support (GSSAPI)
    OpenSSL and GCrypt
    Public Key infrastructure
    Elliptic Curve DSA (ECDSA) support (with OpenSSL)
    Elliptic Curve Diffie Hellman (ECDH) support
    Asynchronous (non-blocking) support
Probably it might help to reduce the implementation time. Not sure if I would be able to build the plugin myself.
Regards,
Nick