Appendix H: PuTTY authentication plugin protocol

This appendix contains the specification for the protocol spoken over local IPC between PuTTY and an authentication helper plugin.

If you already have an authentication plugin and want to configure PuTTY to use it, see section 4.22.3 for how to do that. This appendix is for people writing new authentication plugins.

• H.1 Requirements
• H.2 Transport and configuration
• H.3 Data formats and marshalling
• H.4 Protocol versioning
• H.5 Overview and sequence of events
• H.6 Message formats
  • H.6.1 PLUGIN_INIT
  • H.6.2 PLUGIN_INIT_RESPONSE
  • H.6.3 PLUGIN_INIT_FAILURE
  • H.6.4 PLUGIN_PROTOCOL
  • H.6.5 PLUGIN_PROTOCOL_REJECT
  • H.6.6 PLUGIN_PROTOCOL_ACCEPT
  • H.6.7 PLUGIN_KI_SERVER_REQUEST
  • H.6.8 PLUGIN_KI_SERVER_RESPONSE
  • H.6.9 PLUGIN_KI_USER_REQUEST
  • H.6.10 PLUGIN_KI_USER_RESPONSE
  • H.6.11 PLUGIN_AUTH_SUCCESS
  • H.6.12 PLUGIN_AUTH_FAILURE
• H.7 References