Internet DRAFT - draft-hendrickson-privacypass-geo-extension
draft-hendrickson-privacypass-geo-extension
Privacy Pass S. Hendrickson
Internet-Draft Google
Intended status: Informational C. A. Wood
Expires: 11 January 2024 Cloudflare, Inc.
10 July 2023
Privacy Pass Geolocation Hint Extension
draft-hendrickson-privacypass-geo-extension-00
Abstract
This document describes an extension for Privacy Pass that allows
tokens to encode geolocation hints.
About This Document
This note is to be removed before publishing as an RFC.
The latest revision of this draft can be found at https://chris-
wood.github.io/draft-hendrickson-privacypass-geolocation-extension/
draft-hendrickson-privacypass-expiration-extension.html. Status
information for this document may be found at
https://datatracker.ietf.org/doc/draft-hendrickson-privacypass-geo-
extension/.
Discussion of this document takes place on the Privacy Pass Working
Group mailing list (mailto:privacy-pass@ietf.org), which is archived
at https://mailarchive.ietf.org/arch/browse/privacy-pass/. Subscribe
at https://www.ietf.org/mailman/listinfo/privacy-pass/.
Source for this draft and an issue tracker can be found at
https://github.com/chris-wood/draft-hendrickson-privacypass-
geolocation-extension.
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
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
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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 11 January 2024.
Copyright Notice
Copyright (c) 2023 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/
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 3
3. Geolocation Hint Extension . . . . . . . . . . . . . . . . . 3
4. Security Considerations . . . . . . . . . . . . . . . . . . . 3
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
6. Normative References . . . . . . . . . . . . . . . . . . . . 4
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
Some Privacy Pass token types support binding additional information
to the tokens, often referred to as public metadata.
[AUTH-EXTENSIONS] describes an extension parameter to the basic
PrivateToken HTTP authentication scheme [AUTH-SCHEME] for supplying
this metadata alongside a token. [EXTENDED-ISSUANCE] describes
variants of the basic Privacy Pass issuance protocols
[BASIC-ISSUANCE] that support issuing tokens with public metadata.
However, there are no existing extensions defined to make use of
these protocol extensions.
This document describes an extension for Privacy Pass that allows
tokens to encode geolocation hints. These hints can be used by
origins that redeem tokens to influence its behavior in various ways,
such as determining the content of HTTP responses.
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2. Conventions and Definitions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Geolocation Hint Extension
The geolocation hint extension is an extension used to convey rough
geolocation hints to origins that do not already have accurate or
authoritative mappings for the IP addresses of clients. This can be
particularly useful for cases where IP geolocation mappings have
changed recently, or a client is using a VPN or proxy that may not be
commonly recognized by servers.
The value of this extension is an GeoHintTimestamp, defined as
follows.
struct {
opaque geo_hint<1..2^16-1>;
} GeoHint;
The GeoHintTimestamp fields are defined as follows:
* "geo_hint" is a string formatted as defined in Section 2.1.1 of
[GEOFEED]. It contains a comma-separated list of Alpha2code,
Region, and City. The value SHOULD NOT contain a Postal Code.
As an example, a GeoHint structure corresponding to the
"192.0.2.5,US,US-AL,Alabaster" entry would be:
struct {
opaque geo_hint<1..2^16-1>; // "US,US-AL,Alabaster"
} GeoHint;
4. Security Considerations
Geolocation information can contribute to a client's fingerprint.
Exposing precise geolocation information can therefore lead to
anonymity set partitioning, as described in [ARCHITECTURE]. More
general information regarding the use of extensions and their
possible impact on client privacy can be found in [ARCHITECTURE].
Servers MUST NOT use IP Geolocation Client Hints for making security
or access-control decisions, as the value can be spoofed by a client.
The hint is intended only for use in optimizing behavior.
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5. IANA Considerations
This document registers the following entry into the "Privacy Pass
PrivateToken Extensions" registry.
* Expiration extension
- Type: 0x0002
- Name: Geolocation hint
- Value: GeoHint value as defined in Section 3
- Reference: This document
- Notes: None
6. Normative References
[ARCHITECTURE]
Davidson, A., Iyengar, J., and C. A. Wood, "The Privacy
Pass Architecture", Work in Progress, Internet-Draft,
draft-ietf-privacypass-architecture-13, 15 June 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-
privacypass-architecture-13>.
[AUTH-EXTENSIONS]
Hendrickson, S. and C. A. Wood, "The PrivateToken HTTP
Authentication Scheme Extensions Parameter", Work in
Progress, Internet-Draft, draft-wood-privacypass-auth-
scheme-extensions-00, 10 July 2023,
<https://datatracker.ietf.org/doc/html/draft-wood-
privacypass-auth-scheme-extensions-00>.
[AUTH-SCHEME]
Pauly, T., Valdez, S., and C. A. Wood, "The Privacy Pass
HTTP Authentication Scheme", Work in Progress, Internet-
Draft, draft-ietf-privacypass-auth-scheme-11, 23 June
2023, <https://datatracker.ietf.org/doc/html/draft-ietf-
privacypass-auth-scheme-11>.
[BASIC-ISSUANCE]
Celi, S., Davidson, A., Valdez, S., and C. A. Wood,
"Privacy Pass Issuance Protocol", Work in Progress,
Internet-Draft, draft-ietf-privacypass-protocol-11, 26
June 2023, <https://datatracker.ietf.org/doc/html/draft-
ietf-privacypass-protocol-11>.
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[EXTENDED-ISSUANCE]
"*** BROKEN REFERENCE ***".
[GEOFEED] Kline, E., Duleba, K., Szamonek, Z., Moser, S., and W.
Kumari, "A Format for Self-Published IP Geolocation
Feeds", RFC 8805, DOI 10.17487/RFC8805, August 2020,
<https://www.rfc-editor.org/rfc/rfc8805>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
Acknowledgments
This document received input and feedback from Jim Laskey.
Authors' Addresses
Scott Hendrickson
Google
Email: scott@shendrickson.com
Christopher A. Wood
Cloudflare, Inc.
Email: caw@heapingbits.net
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