See also: http://tools.ietf.org/html/rfc2743
Copyright (c) 2013 iMatix Corporation.
This Specification is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This Specification is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, see http://www.gnu.org/licenses.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.
The ZMTP GSSAPI mechanism provides secure authentication and confidentiality for ZMTP 3.0. This mechanism utilizes the Generic Security Service Application Interface, which provides security services to callers in a generic fashion.
The GSSAPI mechanism uses the greeting as-server field to identify which peer is "client" and which peer is "server".
The mechanism starts with a HELLO command from client to server, and continues with a handshake until each party has authenticated the other and is ready to send confidential information.
All command bodies consist of an 8-character command name, padded with spaces, followed by formatted binary fields. Command bodies may or may not be encrypted dependenting on the underlying security mechanism. The http://rfc.zeromq.org/spec:23 ZMTP 3.0 specification] defines the grammar for the command size. The [ http://tools.ietf.org/html/rfc2743 GSSAPI specification] defines the grammar for the command bodies.