Internet-Draft Privacy.txt File Format June 2024
Sullivan, et al. Expires 28 December 2024 [Page]
Network Working Group
Intended Status:
N. Sullivan
Cryptography Consulting LLC
L. V. D. Peet
TU Delft
G. Smaragdakis
TU Delft
B. Colwell
BringYour, Inc.

A File Format to Aid in Consumer Privacy Enforcement, Research, and Tools


This proposal outlines a new file format called privacy.txt. It follows similar placement on a web server as robots.txt [RFC9309], security.txt [RFC9116], or ads.txt [ADS-TXT], in the / directory or /.well-known directory.

The file format adds structured data for three areas: 1. A machine parsable and complete privacy policy 2. Consumer actions under their privacy rights 3. Cookie disclosures

About This Document

This note is to be removed before publishing as an RFC.

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This Internet-Draft will expire on 28 December 2024.

Table of Contents

1. Introduction

Consumers in many parts of the world have extensive privacy rights under laws such as the GDPR (, the CCPA ( However, without some formalization of a service's privacy policy, it is difficult or often intractable for consumers to exercise those rights; enforcement to verify compliance with laws and develop effective monitoring; and researchers and technologists to develop tools to allow greater adoption and success of privacy practices.

Consumer data originally gets into the cloud by connections from consumer devices to web servers in the cloud. To be able to audit and technically enforce privacy it must be possible to track the privacy policies applied to every byte of consumer data entering the cloud. However, currently the association between a web request and the privacy policy is tenuous, leading to the possibility of incorrect or unverifiable consumer data usage at the very source. This proposal fills that hole by associating structured privacy data with every web server. Just like HTTPS security can be technically enforced, this proposal makes it possible to technically enforce privacy by verifying that the structured privacy information exists and is in good standing before sending data to the server.

This proposal outlines a new file format called privacy.txt. The file format adds structured data for three areas: 1. A machine-parsable and complete privacy policy 2. Consumer actions under their privacy rights 3. Cookie disclosures

1.1. General file format

The file format is UTF8 text [RFC3629] and lists Field:Value, one per line. \n is used a line break. Excess whitespace and lines that start with # are ignored. All field are NOT case sensitive unless mentioned otherwise. Each field MUST appear on its own line. Unless otherwise specified by the field definition, multiple values MUST NOT be chained together for a single field. Unless otherwise indicated in a definition of a particular field, a field MAY appear multiple times.

Implementors should be aware that some of the fields may contain URIs using percent-encoding (as per Section 2.1 of [RFC3986]) and mailto URIs (as per [RFC6068]).

1.2. File placement

For web-based services, organizations MUST place the "privacy.txt" file under the "/.well-known/" path, e.g., as per [RFC8615] of a domain name or IP address. For legacy compatibility, a "privacy.txt" file might be placed at the top-level path or redirect (as per Section 6.4 of [RFC7231]) to the "privacy.txt" file under the "/.well-known/" path. If a "privacy.txt" file is present in both locations, the one in the "/.well-known/" path MUST be used.

The file MUST be accessed via HTTP 1.0 or a higher version, and the file access MUST use the "https" scheme (as per Section 2.7.2 of [RFC7230]). It MUST have a Content-Type of "text/plain" with the default charset parameter set to "utf-8" (as per Section 4.1.3 of [RFC2046]).

Retrieval of "privacy.txt" files and resources indicated within such files may result in a redirect (as per Section 6.4 of [RFC7231]).

1.3. Valid value formats

1.3.1. NAME

A string of maximum 50 characters. The string can contain any US-ASCII characters except for: control characters (ASCII characters 0 up to 31 and ASCII character 127) or separator characters (space, tab and the characters: ( ) < > @ , ; : \ " / [ ] ? = { }). This field is case sensitive.


The country code MUST follow 2-letter [ISO3166].


The language code MUST follow 2-letter [ISO639].

A boolean attribute, using 0 or 1 representing false (0) and true (1), whether a consent banner is present.

String attribute can be set to: 1. Label of consent platforms according to [MANAGERS] (extendable) 2. non-specific custom or any identifying name if it is a custom banner 3. non-detected when there is no banner


An integer attribute of the duration between 0 and the maximum duration. -1 can be used for session cookies.

1.4. A machine parsable and complete privacy policy

It is currently difficult to associate a complete privacy policy text with a service for a number of reasons. First, even though it must be linked from the company webpage, there is not a canonical URL. Second, it is common for services to use client-side rendering, interactive elements, break out links for addendums, and server rules to prevent machine parsing/scraping.

This file format proposes two fields for the privacy policy. One or both can be used, depending on the policy format.

Both privacy policy fields can be used for multi-language support, the default entry is the default language of the privacy policy.

1.4.1. Issuer information

Mandatory, single entry

Entity: NAME Entity-country: COUNTRY_CODE

The legal name of the entity issuing the privacy policy.

The current and historical mapping of hostname to entity can be used as a canonical key to associate privacy reputation or enforcement actions similar to a certificate authority. This proposal does not outline what a privacy authority would look like.

1.4.2. Privacy policy text

Optional, single entry

Privacy-policy-text: URL

Multi-language support: Privacy-policy-text-[LANGUAGE_CODE]: URL

A complete privacy policy in a single UTF-8 text file that can be downloaded by any user agent or machine tool. This MUST include all addendums in the text file. It MUST NOT include links. Information about contact and consumer actions are covered in this file format and do not need to be linked to in the policy text.

1.4.3. Privacy policy URL

Mandatory, single entry

Privacy-policy: URL

Multi-language support:

Privacy-policy-[LANGUAGE_CODE]: URL

If Privacy-policy-text is present, this can simply point to the existing privacy policy, in whatever form it currently exists. Otherwise, it must point to a machine parsable/scrapable static HTML file that contains the complete policy on a single page.

1.5. Consumer actions under their privacy rights

This file format proposed fields to structure the consumer actions described in the privacy policy and commonly required by law. Currently it is difficult to get even an email that can service privacy requests from many top-100 site privacy policies. There is currently no law about how easy it should be to take privacy actions, similar to the US CAN-SPAM Act [CAN-SPAM], which led to an industry standard one-click link for marketing emails. The spirit of these fields is similar, to make it as easy as possible for a consumer to exercise their privacy rights.

In this section, a one-click URL refers to a URL that can process a request without requiring a customer password or login. The URL should take customer identification such as email and verify as necessary to complete the request.

It is allowed to have multiple conforming Action-* values for the same action.

An API standard to make privacy actions more toolable is not covered in this proposal. This proposal could be extended in the future to allow some well-defined API actions given there is at least one other non-assisted option available.

1.5.1. Privacy contact email

Mandatory, single entry

Contact: mailto:EMAIL

An email contact for the privacy office must be given. This email must be able to handle consumer requests via email where there is not an applicable Action-* field for the request. Responses can ask for additional verification but should not require customer password or login. If Action-* fields are defined for all applicable consumer requests, this email does not need to handle any requests. This proposal imagines companies would build self-service one-click URLs for all consumer actions as the most scalable outcome.

1.5.2. Actions Account and data deletion

Optional, single entry

Action-delete-account-and-data: mailto:EMAIL|URL

Email or one-click URL to process an account and data deletion request. Personal data deletion

Optional, single entry

Action-delete-personal-data: mailto:EMAIL|URL

Email or one-click URL to process a personal data deletion request. Opt out of third-party data sharing

Optional, single entry

Action-opt-out-sharing:mailto: EMAIL|URL

Email or one-click URL to opt out of personal data sharing with third parties. List of third parties

Optional, single entry

Action-shared-list:mailto: EMAIL|URL

Email or one-click URL to get a list of all third parties where personal data has been shared. Opt out of marketing

Optional, single entry

Action-opt-out-marketing: mailto:EMAIL|URL

Email or one-click URL to opt out of marketing.

2. Other records

Other records that are not part of the privacy.txt protocol may be included. For example, a regulation-specific record like action-fcra-freeze could be added to comply to FCRA obligations.

3. 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.

4. Security Considerations

Following this file format makes it easier for consumers to take privacy actions, similar to one-click unsubscribe. Removing the barrier to actions makes it easier to make mistakes. It would be reasonable to allow some grace period of undo in case of a security incident.

5. IANA Considerations

This document has no IANA actions.

6. References

6.1. Normative References

International Organization for Standardization (ISO), "Codes for the representation of names of countries and their subdivisions - Part 1: Country codes", , <>.
International Organization for Standardization (ISO), "Code for individual languages and language groups", , <>.
Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types", RFC 2046, DOI 10.17487/RFC2046, , <>.
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <>.
Yergeau, F., "UTF-8, a transformation format of ISO 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, , <>.
Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, DOI 10.17487/RFC3986, , <>.
Duerst, M., Masinter, L., and J. Zawinski, "The 'mailto' URI Scheme", RFC 6068, DOI 10.17487/RFC6068, , <>.
Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing", RFC 7230, DOI 10.17487/RFC7230, , <>.
Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content", RFC 7231, DOI 10.17487/RFC7231, , <>.
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <>.
Nottingham, M., "Well-Known Uniform Resource Identifiers (URIs)", RFC 8615, DOI 10.17487/RFC8615, , <>.

6.2. Informative References

IAB Tech Lab, "Ads.txt 1.1 Specification", , <>.
Federal Communications Commission (FCC), "CAN-SPAM Act: A Compliance Guide for Business", n.d., <>.
Peet, L. V. D., "Increasing privacy-related transparency on the web using a self-disclosing standard", , <>.
"Consent Manager List", n.d., <>.
Foudil, E. and Y. Shafranovich, "A File Format to Aid in Security Vulnerability Disclosure", RFC 9116, DOI 10.17487/RFC9116, , <>.
Koster, M., Illyes, G., Zeller, H., and L. Sassman, "Robots Exclusion Protocol", RFC 9309, DOI 10.17487/RFC9309, , <>.


Authors' Addresses

Nick Sullivan
Cryptography Consulting LLC
Louise Van Der Peet
TU Delft
Georgios Smaragdakis
TU Delft
Brien Colwell
BringYour, Inc.