Token Binding for Transport Layer Security (TLS) Version 1.3 Connections
draft-ietf-tokbind-tls13-01

Document Type Active Internet-Draft (tokbind WG)
Last updated 2018-05-21
Replaces draft-nharper-tokbind-tls13
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Network Working Group                                          N. Harper
Internet-Draft                                               Google Inc.
Updates: TBNEGO (if approved)                               May 21, 2018
Intended status: Standards Track
Expires: November 22, 2018

Token Binding for Transport Layer Security (TLS) Version 1.3 Connections
                      draft-ietf-tokbind-tls13-01

Abstract

   Negotiation of the Token Binding protocol is only defined for
   Transport Layer Security (TLS) versions 1.2 and earlier.  Token
   Binding users may wish to use it with TLS 1.3; this document defines
   a backwards compatible way to negotiate Token Binding on TLS 1.3
   connections.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on November 22, 2018.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

1.  Introduction

   Negotiating Token Binding using a TLS [I-D.ietf-tls-tls13] extension
   as described in [I-D.ietf-tokbind-negotiation] is fairly
   straightforward, but is restricted to TLS 1.2 and earlier.  Only one
   minor change is needed to use this extension to negotiate Token
   Binding on connections using TLS 1.3 and later.  Instead of the
   server putting the "token_binding" extension in the ServerHello like
   in TLS 1.2, in TLS 1.3 the server puts it in EncryptedExtensions
   instead.

   This document also non-normatively provides a clarification for the
   definition of the TokenBinding.signature field from
   [I-D.ietf-tokbind-protocol], since TLS 1.3 defines an alternate (but
   API-compatible) exporter mechanism to the one in [RFC5705] used in
   [I-D.ietf-tokbind-protocol].

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  Token Binding TLS Extension

   In TLS 1.3, the "token_binding" TLS extension may be present only in
   ClientHello and EncryptedExtensions handshake messages.  The format
   of the "token_binding" TLS extension remains the same as defined in
   [I-D.ietf-tokbind-negotiation].

   A client puts the "token_binding" TLS extension in its ClientHello to
   indicate its support for the Token Binding protocol.  The client
   should follow the same rules for when to send this extension and the
   contents of its data as in section 2 of
   [I-D.ietf-tokbind-negotiation].  Since the "token_binding" extension
   remains unchanged from TLS 1.2 to TLS 1.3 in the ClientHello, a
   client sending the "token_binding" extension in a TLS 1.3 ClientHello
   is backwards compatible with a server that only supports TLS 1.2.

   A server puts the "token_binding" TLS extension in the
   EncryptedExtensions message following its ServerHello to indicate
   support for the Token Binding protocol and to select protocol version
   and key parameters.  The server includes the extension following the

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   same rules as section 3 of [I-D.ietf-tokbind-negotiation], with the
   following changes:

   o  The "token_binding" TLS extension is in EncryptedExtensions
      instead of ServerHello.

   o  The server MUST NOT include both the "token_binding" extension and
      the "early_data" extension on the same connection.

3.  Interaction with 0-RTT Data
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