Privacy Pass Protocol Specification
draft-ietf-privacypass-protocol-01

Document Type Active Internet-Draft (privacypass WG)
Authors Sofia Celi  , Alex Davidson  , Armando Faz-Hern├índez 
Last updated 2021-02-22
Replaces draft-davidson-pp-protocol
Stream Internet Engineering Task Force (IETF)
Intended RFC status (None)
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Network Working Group                                            S. Celi
Internet-Draft                                                Cloudflare
Intended status: Informational                               A. Davidson
Expires: 23 August 2021                                              LIP
                                                        A. Faz-Hernandez
                                                              Cloudflare
                                                        19 February 2021

                  Privacy Pass Protocol Specification
                   draft-ietf-privacypass-protocol-01

Abstract

   This document specifies the Privacy Pass protocol.  This protocol
   provides anonymity-preserving authorization of clients to servers.
   In particular, client re-authorization events cannot be linked to any
   previous initial authorization.  Privacy Pass is intended to be used
   as a performant protocol in the application-layer.

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 https://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 23 August 2021.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Celi, et al.             Expires 23 August 2021                 [Page 1]
Internet-Draft                 PP protocol                 February 2021

   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
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   provided without warranty as described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Background  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  Motivating use-cases  . . . . . . . . . . . . . . . . . .   4
     3.2.  Anonymity and security guarantees . . . . . . . . . . . .   5
     3.3.  Basic assumptions . . . . . . . . . . . . . . . . . . . .   5
   4.  Protocol description  . . . . . . . . . . . . . . . . . . . .   5
     4.1.  Server setup  . . . . . . . . . . . . . . . . . . . . . .   6
     4.2.  Client setup  . . . . . . . . . . . . . . . . . . . . . .   6
     4.3.  Issuance phase  . . . . . . . . . . . . . . . . . . . . .   6
     4.4.  Redemption phase  . . . . . . . . . . . . . . . . . . . .   8
       4.4.1.  Client info . . . . . . . . . . . . . . . . . . . . .   8
       4.4.2.  Double-spend protection . . . . . . . . . . . . . . .   9
     4.5.  Handling errors . . . . . . . . . . . . . . . . . . . . .   9
   5.  Functionality . . . . . . . . . . . . . . . . . . . . . . . .   9
     5.1.  Data structures . . . . . . . . . . . . . . . . . . . . .   9
       5.1.1.  Ciphersuite . . . . . . . . . . . . . . . . . . . . .   9
       5.1.2.  Keys  . . . . . . . . . . . . . . . . . . . . . . . .   9
       5.1.3.  CommitRequest . . . . . . . . . . . . . . . . . . . .  10
       5.1.4.  CommitResponse  . . . . . . . . . . . . . . . . . . .  10
       5.1.5.  IssuanceInput . . . . . . . . . . . . . . . . . . . .  10
       5.1.6.  IssuanceResponse  . . . . . . . . . . . . . . . . . .  10
       5.1.7.  RedemptionToken . . . . . . . . . . . . . . . . . . .  11
       5.1.8.  RedemptionRequest . . . . . . . . . . . . . . . . . .  11
       5.1.9.  RedemptionResponse  . . . . . . . . . . . . . . . . .  11
     5.2.  API functions . . . . . . . . . . . . . . . . . . . . . .  12
       5.2.1.  Prepare . . . . . . . . . . . . . . . . . . . . . . .  12
       5.2.2.  Commit  . . . . . . . . . . . . . . . . . . . . . . .  12
       5.2.3.  Generate  . . . . . . . . . . . . . . . . . . . . . .  12
       5.2.4.  Issue . . . . . . . . . . . . . . . . . . . . . . . .  13
       5.2.5.  Process . . . . . . . . . . . . . . . . . . . . . . .  13
       5.2.6.  Redeem  . . . . . . . . . . . . . . . . . . . . . . .  14
       5.2.7.  Verify  . . . . . . . . . . . . . . . . . . . . . . .  14
     5.3.  Error types . . . . . . . . . . . . . . . . . . . . . . .  14
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