1 Introduction

This document specifies the Passport Server Side Include (SSI) Version 1.4 Protocol (or the Passport SSI Version 1.4 Protocol), also known as the "Passport Tweener" protocol. The Passport SSI Version 1.4 Protocol is based on HTTP (as specified in [RFC2616]) for authenticating a client to a server with the assistance of an authentication server.

Sections 1.8, 2, and 3 of this specification are normative and can contain the terms MAY, SHOULD, MUST, MUST NOT, and SHOULD NOT as defined in RFC 2119. Sections 1.5 and 1.9 are also normative but cannot contain those terms. All other sections and examples in this specification are informative.