Attested TLS Token Binding
draft-mandyam-tokbind-attest-06

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Last updated 2018-07-24
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Token Binding Working Group                                   G. Mandyam
Internet-Draft                                              L. Lundblade
Intended status: Standards Track                                 J. Azen
Expires: January 25, 2019                     Qualcomm Technologies Inc.
                                                           July 24, 2018

                       Attested TLS Token Binding
                    draft-mandyam-tokbind-attest-06

Abstract

   Token binding allows HTTP servers to bind bearer tokens to TLS
   connections.  In order to do this, clients or user agents must prove
   possession of a private key.  However, proof-of-possession of a
   private key becomes truly meaningful to a server when accompanied by
   an attestation statement.  This specification describes extensions to
   the existing token binding protocol to allow for attestation
   statements to be sent along with the related token binding messages.

Status of This Memo

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   This Internet-Draft will expire on January 25, 2019.

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   Copyright (c) 2018 IETF Trust and the persons identified as the
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Mandyam, et al.         Expires January 25, 2019                [Page 1]
Internet-Draft                TokBindAttest                    July 2018

   include Simplified BSD License text as described in Section 4.e of
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Attestation Enhancement to TLS Token Binding Message  . . . .   3
     2.1.  KeyStore Attestation  . . . . . . . . . . . . . . . . . .   4
       2.1.1.  Verification Procedures . . . . . . . . . . . . . . .   4
     2.2.  TPMv2 Attestation . . . . . . . . . . . . . . . . . . . .   5
       2.2.1.  Verification Procedures . . . . . . . . . . . . . . .   5
   3.  Extension Support Negotiation . . . . . . . . . . . . . . . .   6
     3.1.  Negotiating Token Binding Protocol Extensions . . . . . .   7
   4.  Example - Platform Attestation for Anomaly Detection  . . . .   7
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
     5.1.  TLS Extensions Registry . . . . . . . . . . . . . . . . .   8
     5.2.  Token Binding Extensions for Attestation  . . . . . . . .   8
   6.  Security and Privacy Considerations . . . . . . . . . . . . .   9
     6.1.  Attestation Privacy Considerations  . . . . . . . . . . .   9
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   9
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   [I-D.ietf-tokbind-protocol] and [I-D.ietf-tokbind-negotiation]
   describe a framework whereby servers can leverage cryptographically-
   bound authentication tokens in part to create uniquely-identifiable
   TLS bindings that can span multiple connections between a client and
   a server.  Once the use of token binding is negotiated as part of the
   TLS handshake, an application layer message (the Token Binding
   message) may be sent from the client to the relying party whose
   primary purpose is to encapsulate a signature over a value associated
   with the current TLS session.  The payload used for the signature is
   the token binding public key (see [I-D.ietf-tokbind-protocol]).  Use
   of the token binding public key allows for generation of the
   attestation signature once over the lifetime of the public key.

   Proof-of-possession of a private key is useful to a relying party,
   but the associated signature in the Token Binding message does not
   provide an indication as to how the private key is stored and in what
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