Transport Layer Security (TLS) Application Layer Protocol Negotiation Extension

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Document Type Active Internet-Draft (tls WG)
Last updated 2014-02-06 (latest revision 2014-01-24)
Replaces draft-friedl-tls-applayerprotoneg
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Network Working Group                                          S. Friedl
Internet-Draft                                       Cisco Systems, Inc.
Intended status: Standards Track                                A. Popov
Expires: July 28, 2014                                   Microsoft Corp.
                                                              A. Langley
                                                             Google Inc.
                                                              E. Stephan
                                                        January 24, 2014

 Transport Layer Security (TLS) Application Layer Protocol Negotiation


   This document describes a Transport Layer Security (TLS) extension
   for application layer protocol negotiation within the TLS handshake.
   For instances in which the TLS connection is established over a well
   known TCP/IP port not associated with the desired application layer
   protocol, this extension allows the application layer to negotiate
   which protocol will be used within the TLS connection.

Status of This Memo

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   This Internet-Draft will expire on July 28, 2014.

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Table of Contents

   1.  Introduction
   2.  Requirements Language
   3.  Application Layer Protocol Negotiation
     3.1.  The Application Layer Protocol Negotiation Extension
     3.2.  Protocol Selection
   4.  Design Considerations
   5.  Security Considerations
   6.  IANA Considerations
   7.  Acknowledgements
   8.  References
     8.1.  Normative References
     8.2.  Informative References
   Authors' Addresses

1.  Introduction

   Increasingly, application layer protocols are encapsulated in the TLS
   security protocol [RFC5246].  This encapsulation enables applications
   to use the existing, secure communications links already present on
   port 443 across virtually the entire global IP infrastructure.

   When multiple application protocols are supported on a single server-
   side port number, such as port 443, the client and the server need to
   negotiate an application protocol for use with each connection.  It
   is desirable to accomplish this negotiation without adding network
   round-trips between the client and the server, as each round-trip
   will degrade an end-user's experience.  Further, it would be
   advantageous to allow certificate selection based on the negotiated
   application protocol.

   This document specifies a TLS extension which permits the application
   layer to negotiate protocol selection within the TLS handshake.  This
   work was requested by the HTTPbis WG to address the negotiation of
   HTTP version ([RFC2616], [I-D.ietf-httpbis-http2]) over TLS, however
   ALPN facilitates negotiation of arbitrary application layer

   With ALPN, the client sends the list of supported application
   protocols as part of the TLS ClientHello message.  The server chooses
   a protocol and sends the selected protocol as part of the TLS
   ServerHello message.  The application protocol negotiation can thus
   be accomplished within the TLS handshake, without adding network
   round-trips, and allows the server to associate a different
   certificate with each application protocol, if desired.

2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

3.  Application Layer Protocol Negotiation
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