Exported Authenticators in TLS
draft-ietf-tls-exported-authenticator-09

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TLS                                                          N. Sullivan
Internet-Draft                                           Cloudflare Inc.
Intended status: Standards Track                            May 03, 2019
Expires: November 4, 2019

                     Exported Authenticators in TLS
                draft-ietf-tls-exported-authenticator-09

Abstract

   This document describes a mechanism in Transport Layer Security (TLS)
   to provide an exportable proof of ownership of a certificate that can
   be transmitted out of band and verified by the peer.

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 4, 2019.

Copyright Notice

   Copyright (c) 2019 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
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions and Terminology . . . . . . . . . . . . . . . . .   3
   3.  Authenticator Request . . . . . . . . . . . . . . . . . . . .   3
   4.  Authenticator . . . . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  Authenticator Keys  . . . . . . . . . . . . . . . . . . .   5
     4.2.  Authenticator Construction  . . . . . . . . . . . . . . .   5
       4.2.1.  Certificate . . . . . . . . . . . . . . . . . . . . .   6
       4.2.2.  CertificateVerify . . . . . . . . . . . . . . . . . .   6
       4.2.3.  Finished  . . . . . . . . . . . . . . . . . . . . . .   8
       4.2.4.  Authenticator Creation  . . . . . . . . . . . . . . .   8
   5.  Empty Authenticator . . . . . . . . . . . . . . . . . . . . .   8
   6.  API considerations  . . . . . . . . . . . . . . . . . . . . .   8
     6.1.  The "request" API . . . . . . . . . . . . . . . . . . . .   9
     6.2.  The "get context" API . . . . . . . . . . . . . . . . . .   9
     6.3.  The "authenticate" API  . . . . . . . . . . . . . . . . .   9
     6.4.  The "validate" API  . . . . . . . . . . . . . . . . . . .  10
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
     7.1.  Update of the TLS ExtensionType Registry  . . . . . . . .  10
     7.2.  Update of the TLS Exporter Labels Registry  . . . . . . .  10
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  11
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  11
     10.2.  Informative References . . . . . . . . . . . . . . . . .  12
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   This document provides a way to authenticate one party of a Transport
   Layer Security (TLS) communication to its peer using a certificate
   after the session has been established.  This allows both the client
   and server to prove ownership of additional identities at any time
   after the handshake has completed.  This proof of authentication can
   be exported and transmitted out of band from one party to be
   validated by its peer.

   This mechanism provides two advantages over the authentication that
   TLS natively provides:

   multiple identities -  Endpoints that are authoritative for multiple
      identities - but do not have a single certificate that includes
      all of the identities - can authenticate additional identities
      over a single connection.

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   spontaneous authentication -  Endpoints can authenticate after a