The Token Binding Protocol Version 1.0
draft-ietf-tokbind-protocol-04

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Document Type Active Internet-Draft (tokbind WG)
Last updated 2016-01-08
Replaces draft-popov-token-binding
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Internet Engineering Task Force                            A. Popov, Ed.
Internet-Draft                                               M. Nystroem
Intended status: Standards Track                         Microsoft Corp.
Expires: July 11, 2016                                        D. Balfanz
                                                              A. Langley
                                                             Google Inc.
                                                         January 8, 2016

                 The Token Binding Protocol Version 1.0
                     draft-ietf-tokbind-protocol-04

Abstract

   This document specifies Version 1.0 of the Token Binding protocol.
   The Token Binding protocol allows client/server applications to
   create long-lived, uniquely identifiable TLS [RFC5246] bindings
   spanning multiple TLS sessions and connections.  Applications are
   then enabled to cryptographically bind security tokens to the TLS
   layer, preventing token export and replay attacks.  To protect
   privacy, the TLS Token Binding identifiers are only transmitted
   encrypted and can be reset by the user at any time.

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
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   This Internet-Draft will expire on July 11, 2016.

Copyright Notice

   Copyright (c) 2016 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

Popov, et al.             Expires July 11, 2016                 [Page 1]
Internet-Draft   The Token Binding Protocol Version 1.0     January 2016

   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Token Binding Protocol Overview . . . . . . . . . . . . . . .   3
   3.  Token Binding Protocol Message  . . . . . . . . . . . . . . .   4
   4.  Establishing a TLS Token Binding  . . . . . . . . . . . . . .   7
   5.  TLS Token Binding ID Format . . . . . . . . . . . . . . . . .   7
   6.  Security Token Validation . . . . . . . . . . . . . . . . . .   8
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
     8.1.  Security Token Replay . . . . . . . . . . . . . . . . . .  10
     8.2.  Downgrade Attacks . . . . . . . . . . . . . . . . . . . .  10
     8.3.  Privacy Considerations  . . . . . . . . . . . . . . . . .  10
     8.4.  Token Binding Key Sharing Between Applications  . . . . .  11
     8.5.  Triple Handshake Vulnerability in TLS 1.2 and Older TLS
           Versions  . . . . . . . . . . . . . . . . . . . . . . . .  11
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  11
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  11
     10.2.  Informative References . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  13

1.  Introduction

   Servers generate various security tokens (e.g.  HTTP cookies, OAuth
   tokens) for applications to access protected resources.  Any party in
   possession of such token gains access to the protected resource.
   Attackers export bearer tokens from the user's machine, present them
   to the servers, and impersonate authenticated users.  The idea of
   Token Binding is to prevent such attacks by cryptographically binding
   security tokens to the TLS layer.

   A TLS Token Binding is established by the user agent generating a
   private-public key pair (possibly within a secure hardware module,
   such as TPM) per target server, and proving possession of the private
   key on every TLS connection to the target server.  The proof of
   possession involves signing the exported keying material [RFC5705]
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