Exported Authenticators in TLS
draft-ietf-tls-exported-authenticator-13

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TLS                                                          N. Sullivan
Internet-Draft                                           Cloudflare Inc.
Intended status: Standards Track                           June 26, 2020
Expires: December 28, 2020

                     Exported Authenticators in TLS
                draft-ietf-tls-exported-authenticator-13

Abstract

   This document describes a mechanism in Transport Layer Security (TLS)
   for peers to provide a proof of ownership of an identity, such as an
   X.509 certificate.  This proof can be exported by one peer,
   transmitted out-of-band to the other peer, and verified by the
   receiving 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
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   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 December 28, 2020.

Copyright Notice

   Copyright (c) 2020 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
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   (https://trustee.ietf.org/license-info) in effect on the date of
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   described in the Simplified BSD License.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions and Terminology . . . . . . . . . . . . . . . . .   3
   3.  Message Sequences . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Authenticator Request . . . . . . . . . . . . . . . . . . . .   4
   5.  Authenticator . . . . . . . . . . . . . . . . . . . . . . . .   5
     5.1.  Authenticator Keys  . . . . . . . . . . . . . . . . . . .   6
     5.2.  Authenticator Construction  . . . . . . . . . . . . . . .   6
       5.2.1.  Certificate . . . . . . . . . . . . . . . . . . . . .   7
       5.2.2.  CertificateVerify . . . . . . . . . . . . . . . . . .   8
       5.2.3.  Finished  . . . . . . . . . . . . . . . . . . . . . .   9
       5.2.4.  Authenticator Creation  . . . . . . . . . . . . . . .   9
   6.  Empty Authenticator . . . . . . . . . . . . . . . . . . . . .   9
   7.  API considerations  . . . . . . . . . . . . . . . . . . . . .  10
     7.1.  The "request" API . . . . . . . . . . . . . . . . . . . .  10
     7.2.  The "get context" API . . . . . . . . . . . . . . . . . .  10
     7.3.  The "authenticate" API  . . . . . . . . . . . . . . . . .  11
     7.4.  The "validate" API  . . . . . . . . . . . . . . . . . . .  11
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
     8.1.  Update of the TLS ExtensionType Registry  . . . . . . . .  12
     8.2.  Update of the TLS Exporter Labels Registry  . . . . . . .  12
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  12
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  12
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  13
     11.2.  Informative References . . . . . . . . . . . . . . . . .  14
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   This document provides a way to authenticate one party of a Transport
   Layer Security (TLS) connection to its peer using a Certificate
   message 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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