Trust Assertions for Certificate Keys
draft-perrin-tls-tack-02

TLS Working Group                                         M. Marlinspike
Internet-Draft                                            T. Perrin, Ed.
Intended status: Standards Track                         January 7, 2013
Expires: July 11, 2013

                 Trust Assertions for Certificate Keys
                      draft-perrin-tls-tack-02.txt

Abstract

   This document defines a TLS Extension that enables a TLS server to
   support "pinning" to a self-chosen signing key.  A client contacting
   a pinned host will require the server to present a signature from the
   signing key over the TLS server's public key.

Status of this Memo

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   This Internet-Draft will expire on July 11, 2013.

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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Requirements notation  . . . . . . . . . . . . . . . . . .  3
   2.  Overview . . . . . . . . . . . . . . . . . . . . . . . . . . .  4
     2.1.  Tack life cycle  . . . . . . . . . . . . . . . . . . . . .  4
     2.2.  Pin life cycle . . . . . . . . . . . . . . . . . . . . . .  5
   3.  TACK Extension . . . . . . . . . . . . . . . . . . . . . . . .  6
     3.1.  Definition of TackExtension  . . . . . . . . . . . . . . .  6
     3.2.  Explanation of TackExtension fields  . . . . . . . . . . .  7
       3.2.1.  Tack fields  . . . . . . . . . . . . . . . . . . . . .  7
       3.2.2.  TackExtension fields . . . . . . . . . . . . . . . . .  7
   4.  Client processing  . . . . . . . . . . . . . . . . . . . . . .  8
     4.1.  TACK pins  . . . . . . . . . . . . . . . . . . . . . . . .  8
     4.2.  High-level client processing . . . . . . . . . . . . . . .  8
     4.3.  Client processing details  . . . . . . . . . . . . . . . .  9
       4.3.1.  Check whether the TLS handshake is valid . . . . . . .  9
       4.3.2.  Check tack generations and update min_generations  . .  9
       4.3.3.  Determine the store's status . . . . . . . . . . . . . 10
       4.3.4.  Pin activation (optional)  . . . . . . . . . . . . . . 10
   5.  Application protocols and TACK . . . . . . . . . . . . . . . . 12
     5.1.  Pin scope  . . . . . . . . . . . . . . . . . . . . . . . . 12
     5.2.  TLS negotiation  . . . . . . . . . . . . . . . . . . . . . 12
     5.3.  Certificate verification . . . . . . . . . . . . . . . . . 12
   6.  Fingerprints . . . . . . . . . . . . . . . . . . . . . . . . . 13
   7.  Advice . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
     7.1.  For server operators . . . . . . . . . . . . . . . . . . . 14
     7.2.  For client implementers  . . . . . . . . . . . . . . . . . 15
   8.  Security considerations  . . . . . . . . . . . . . . . . . . . 16
     8.1.  For server operators . . . . . . . . . . . . . . . . . . . 16
     8.2.  For client implementers  . . . . . . . . . . . . . . . . . 16
     8.3.  Note on algorithm agility  . . . . . . . . . . . . . . . . 17
   9.  IANA considerations  . . . . . . . . . . . . . . . . . . . . . 18
     9.1.  New entry for the TLS ExtensionType Registry . . . . . . . 18
   10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 19
   11. Normative references . . . . . . . . . . . . . . . . . . . . . 20
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21

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