SILC SKE Interface
Header: silcske.h
DESCRIPTION

     Implementation of the SILC Key Exchange Protocol (SKE). The SKE protocol
     is used to negotiate secret key material between two parties, to be used
     as session key or some other key. For example, when client connects to
     server SKE is performed to exchange public keys, and to generate the key
     that is then used as session key. Two clients can execute SKE as well
     two create secret key material for securing for example file transfer
     stream.

     SKE is based on Diffie-Hellman, and it derives its functionality from
     SSH2 Key Exchange protocol, OAKLEY Key Determination protocol and
     Station-To-Station (STS) protocols.

     This SKE implementation provides easy interface for application
     that wants to use SKE. In fact, the interface is designed to be
     application independent, and does not expect that the application using
     SKE would actually relate in any way to SILC. Hence, the interface
     can be used in any kind of application needing to perform key exchange
     protocol with two parties. The network connection is also handled
     outside the SKE interface. For the interface application must provide
     a packet sending function which SKE library can call when it wants
     to send packet to the remote host. The actual network connection
     therefore is handled in the application and not by the SKE library.

     The protocol has initiator and responder. The initiator is the one
     that starts the protocol, and the responder is the one that receives
     negotiation request. The protocol has phases, and the interface is
     split into several phases that the application may call when
     needed. Heavy operations has been splitted so that application may
     call next phase with a timeout to give processing times to other
     things in the application. On the other hand, if application does
     not care about this it may call the phases immediately without any
     timeout.