Privacy Pass HTTP API

Document Type Active Internet-Draft (privacypass WG)
Author Steven Valdez 
Last updated 2021-01-05
Replaces draft-svaldez-pp-http-api
Stream Internet Engineering Task Force (IETF)
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Network Working Group                                          S. Valdez
Internet-Draft                                                Google LLC
Intended status: Informational                            5 January 2021
Expires: 9 July 2021

                         Privacy Pass HTTP API


   This document specifies an integration for Privacy Pass over an HTTP
   API, along with recommendations on how key commitments are stored and
   accessed by HTTP-based consumers.

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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   This Internet-Draft will expire on 9 July 2021.

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

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   Please review these documents carefully, as they describe your rights
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Table of Contents

   1.  Introduction
     1.1.  Terminology
     1.2.  Layout
     1.3.  Requirements
   2.  Privacy Pass HTTP API Wrapping
   3.  Server key registry
     3.1.  Key Registry
     3.2.  Server Configuration Retrieval
   4.  Key Commitment Retrieval
   5.  Privacy Pass Issuance
   6.  Privacy Pass Redemption
     6.1.  Generic Token Redemption
     6.2.  Direct Redemption
     6.3.  Delegated Redemption
   7.  Security Considerations
   8.  IANA Considerations
     8.1.  Well-Known URI
   9.  Normative References
   Author's Address

1.  Introduction

   The Privacy Pass protocol as described in
   [draft-davidson-pp-protocol] can be integrated with a number of
   different settings, from server to server communication to browsing
   the internet.

   In this document, we will provide an API to use for integrating
   Privacy Pass with an HTTP framework.  Providing the format of HTTP
   requests and responses needed to implement the Privacy Pass protocol.

1.1.  Terminology

   We use the same definition of server and client that is used in
   [draft-davidson-pp-protocol] and [draft-davidson-pp-architecture].

   We assume that all protocol messages are encoded into raw byte format
   before being sent.  We use the TLS presentation language [RFC8446] to
   describe the structure of protocol messages.

1.2.  Layout

   *  Section 2: Describes the wrapping of messages within HTTP

   *  Section 3: Describes how HTTP clients retrieve server
      configurations and key commitments.

   *  Section 5: Describes how issuance requests are performed via a
      HTTP API.

   *  Section 6: Describes how redemption requests are performed via a
      HTTP API.

1.3.  Requirements

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

2.  Privacy Pass HTTP API Wrapping

   Messages from HTTP-based clients to HTTP-based servers are performed
   as GET and POST requests.  The messages are sent via the "Sec-
   Privacy-Pass" header.

   "Sec-Privacy-Pass" is a Dictionary Structured Header
   [draft-ietf-httpbis-header-structure-15].  The dictionary has two

   *  "type" whose value is a String conveying the function that is
      being performed with this request.

   *  "body" whose value is a byte sequence containing a Privacy Pass
      protocol message.

   Note that the requests may contain addition Headers, request data and
   URL parameters that are not specified here, these extra fields should
   be ignored, though may be used by the server to determine whether to
   fulfill the requested issuance/redemption.

3.  Server key registry

   A client SHOULD fetch a server's current public key information prior
   to performing issuance and redemption.  This configuration is
   accessible via a "CONFIG_ENDPOINT", either provided by the server or
   by a global registry that provides consistency and anonymization
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