Gossiping in CT
draft-ietf-trans-gossip-01

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Document Type Active Internet-Draft (trans WG)
Last updated 2015-10-19
Replaces draft-linus-trans-gossip-ct
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TRANS                                                        L. Nordberg
Internet-Draft                                                  NORDUnet
Intended status: Experimental                                 D. Gillmor
Expires: April 22, 2016                                             ACLU
                                                               T. Ritter

                                                        October 20, 2015

                            Gossiping in CT
                       draft-ietf-trans-gossip-01

Abstract

   The logs in Certificate Transparency are untrusted in the sense that
   the users of the system don't have to trust that they behave
   correctly since the behaviour of a log can be verified to be correct.

   This document tries to solve the problem with logs presenting a
   "split view" of their operations.  It describes three gossiping
   mechanisms for Certificate Transparency: SCT Feedback, STH
   Pollination and Trusted Auditor Relationship.

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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   Drafts is at http://datatracker.ietf.org/drafts/current/.

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   time.  It is inappropriate to use Internet-Drafts as reference
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   This Internet-Draft will expire on April 22, 2016.

Copyright Notice

   Copyright (c) 2015 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

Nordberg, et al.         Expires April 22, 2016                 [Page 1]
Internet-Draft               Gossiping in CT                October 2015

   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Defining the problem  . . . . . . . . . . . . . . . . . . . .   3
   3.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Terminology and data flow . . . . . . . . . . . . . . . . . .   5
   5.  Who gossips with whom . . . . . . . . . . . . . . . . . . . .   6
   6.  What to gossip about and how  . . . . . . . . . . . . . . . .   6
   7.  Gossip Mechanisms . . . . . . . . . . . . . . . . . . . . . .   6
     7.1.  SCT Feedback  . . . . . . . . . . . . . . . . . . . . . .   6
       7.1.1.  HTTPS client to server  . . . . . . . . . . . . . . .   7
       7.1.2.  HTTPS server to auditors  . . . . . . . . . . . . . .   9
       7.1.3.  SCT Feedback data format  . . . . . . . . . . . . . .  10
     7.2.  STH pollination . . . . . . . . . . . . . . . . . . . . .  10
       7.2.1.  HTTPS Clients and Proof Fetching  . . . . . . . . . .  12
       7.2.2.  STH Pollination without Proof Fetching  . . . . . . .  13
       7.2.3.  Auditor and Monitor Action  . . . . . . . . . . . . .  13
       7.2.4.  STH Pollination data format . . . . . . . . . . . . .  13
     7.3.  Trusted Auditor Stream  . . . . . . . . . . . . . . . . .  14
       7.3.1.  Trusted Auditor data format . . . . . . . . . . . . .  14
   8.  3-Method Ecosystem  . . . . . . . . . . . . . . . . . . . . .  14
     8.1.  SCT Feedback  . . . . . . . . . . . . . . . . . . . . . .  15
     8.2.  STH Pollination . . . . . . . . . . . . . . . . . . . . .  15
     8.3.  Trusted Auditor Relationship  . . . . . . . . . . . . . .  16
     8.4.  Interaction . . . . . . . . . . . . . . . . . . . . . . .  17
   9.  Security considerations . . . . . . . . . . . . . . . . . . .  17
     9.1.  Censorship/Blocking considerations  . . . . . . . . . . .  17
     9.2.  Privacy considerations  . . . . . . . . . . . . . . . . .  19
       9.2.1.  Privacy and SCTs  . . . . . . . . . . . . . . . . . .  19
       9.2.2.  Privacy in SCT Feedback . . . . . . . . . . . . . . .  19
       9.2.3.  Privacy for HTTPS clients performing STH Proof
               Fetching  . . . . . . . . . . . . . . . . . . . . . .  20
       9.2.4.  Privacy in STH Pollination  . . . . . . . . . . . . .  20
       9.2.5.  Privacy in STH Interaction  . . . . . . . . . . . . .  21
       9.2.6.  Trusted Auditors for HTTPS Clients  . . . . . . . . .  21
       9.2.7.  HTTPS Clients as Auditors . . . . . . . . . . . . . .  22
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