Privacy Pass: Architectural Framework
draft-davidson-pp-architecture-00

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Network Working Group                                        A. Davidson
Internet-Draft                                       Cloudflare Portugal
Intended status: Informational                              9 March 2020
Expires: 10 September 2020

                 Privacy Pass: Architectural Framework
                   draft-davidson-pp-architecture-00

Abstract

   This document specifies the architectural framework for constructing
   secure and privacy-preserving instantiations of the Privacy Pass
   protocol (as described in [draft-davidson-pp-protocol]).  The
   framework refers to the entire ecosystem of Privacy Pass clients and
   servers.  This document makes recommendations on how this ecosystem
   should be constructed to ensure the privacy of clients and the
   security of all participating entities.

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
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   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 10 September 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
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of 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

Davidson                Expires 10 September 2020               [Page 1]
Internet-Draft               PP architecture                  March 2020

   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  . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   5
     1.2.  Layout  . . . . . . . . . . . . . . . . . . . . . . . . .   5
   2.  Architectural ecosystem assumptions . . . . . . . . . . . . .   6
     2.1.  Servers . . . . . . . . . . . . . . . . . . . . . . . . .   6
       2.1.1.  Long-term signing . . . . . . . . . . . . . . . . . .   7
     2.2.  Clients . . . . . . . . . . . . . . . . . . . . . . . . .   7
     2.3.  Global configuration store  . . . . . . . . . . . . . . .   8
   3.  Protocol integration policy . . . . . . . . . . . . . . . . .   8
     3.1.  Recap: Protocol API . . . . . . . . . . . . . . . . . . .   9
     3.2.  Server interfaces . . . . . . . . . . . . . . . . . . . .   9
       3.2.1.  SERVER_KEY_GEN  . . . . . . . . . . . . . . . . . . .   9
       3.2.2.  SERVER_STORE_CONFIG . . . . . . . . . . . . . . . . .  10
       3.2.3.  SERVER_CONFIG_RETRIEVAL . . . . . . . . . . . . . . .  11
       3.2.4.  SERVER_HELLO  . . . . . . . . . . . . . . . . . . . .  11
       3.2.5.  SERVER_ISSUE  . . . . . . . . . . . . . . . . . . . .  12
       3.2.6.  SERVER_REDEEM . . . . . . . . . . . . . . . . . . . .  13
       3.2.7.  SERVER_DOUBLE_SPEND_CHECK . . . . . . . . . . . . . .  13
       3.2.8.  SERVER_DOUBLE_SPEND_STORE . . . . . . . . . . . . . .  14
     3.3.  Client interfaces . . . . . . . . . . . . . . . . . . . .  14
       3.3.1.  CLIENT_CONFIG_RETRIEVAL . . . . . . . . . . . . . . .  14
       3.3.2.  CLIENT_ISSUE_GEN  . . . . . . . . . . . . . . . . . .  16
       3.3.3.  CLIENT_ISSUE_FINISH . . . . . . . . . . . . . . . . .  16
       3.3.4.  CLIENT_REDEEM . . . . . . . . . . . . . . . . . . . .  17
       3.3.5.  CLIENT_ISSUE_STORAGE  . . . . . . . . . . . . . . . .  18
       3.3.6.  CLIENT_ISSUE_RETRIEVAL  . . . . . . . . . . . . . . .  18
       3.3.7.  CLIENT_TOKEN_STORAGE  . . . . . . . . . . . . . . . .  18
       3.3.8.  CLIENT_TOKEN_RETRIEVAL  . . . . . . . . . . . . . . .  18
     3.4.  Global configuration registry interfaces  . . . . . . . .  19
       3.4.1.  GLOBAL_CONFIG_UPDATE  . . . . . . . . . . . . . . . .  19
       3.4.2.  GLOBAL_CONFIG_RETRIEVAL . . . . . . . . . . . . . . .  20
   4.  Key management framework  . . . . . . . . . . . . . . . . . .  21
     4.1.  Global configuration  . . . . . . . . . . . . . . . . . .  22
     4.2.  Configuration structure . . . . . . . . . . . . . . . . .  22
     4.3.  Configuration updates #{config-update}  . . . . . . . . .  24
     4.4.  Client retrieval  . . . . . . . . . . . . . . . . . . . .  24