Registry and Signature Agent card for Web bot auth
draft-meunier-webbotauth-registry-00
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| Authors | Maxime Guerreiro , Thibault Meunier | ||
| Last updated | 2025-09-05 | ||
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draft-meunier-webbotauth-registry-00
Web Bot Auth M. Guerreiro
Internet-Draft T. Meunier
Intended status: Informational Cloudflare
Expires: 9 March 2026 5 September 2025
Registry and Signature Agent card for Web bot auth
draft-meunier-webbotauth-registry-00
Abstract
This document describes a JSON based format for clients using
[DIRECTORY] to advertise information about themselves.
This document describes a JSON-based "Signature Agent Card" format
for signature agent using [DIRECTORY] to advertise metadata about
themselve. This includes identity, purpose, rate expectations, and
cryptographic keys. It also establishes an IANA registry for
Signature Agent Card parameters, enabling extensible and
interoperable discovery of agent information.
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://thibmeu.github.io/http-message-signatures-directory/draft-
meunier-webbotauth-registry.html. Status information for this
document may be found at https://datatracker.ietf.org/doc/draft-
meunier-webbotauth-registry/.
Discussion of this document takes place on the Web Bot Auth Working
Group mailing list (mailto:web-bot-auth@ietf.org), which is archived
at https://mailarchive.ietf.org/arch/browse/web-bot-auth/. Subscribe
at https://www.ietf.org/mailman/listinfo/web-bot-auth/.
Source for this draft and an issue tracker can be found at
https://github.com/thibmeu/http-message-signatures-directory.
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 9 March 2026.
Copyright Notice
Copyright (c) 2025 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
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 3
3. Signature Agent Card . . . . . . . . . . . . . . . . . . . . 3
3.1. Name . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Contact . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.3. Logo . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.4. Expected user agent . . . . . . . . . . . . . . . . . . . 5
3.5. robots.txt product token . . . . . . . . . . . . . . . . 5
3.6. robots.txt compliance . . . . . . . . . . . . . . . . . . 5
3.7. Trigger . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.8. Purpose . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.9. Targeted content . . . . . . . . . . . . . . . . . . . . 6
3.10. Rate control . . . . . . . . . . . . . . . . . . . . . . 6
3.11. Rate expectation . . . . . . . . . . . . . . . . . . . . 6
3.12. Known URLs . . . . . . . . . . . . . . . . . . . . . . . 7
3.13. Keys . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4. Discovery . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.1. Out-of-band communication between client and origin . . . 8
4.1.1. Public list . . . . . . . . . . . . . . . . . . . . . 8
4.1.2. Signature-Agent-Card header . . . . . . . . . . . . . 8
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 8
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
7.1. Signature Agent Card Parameters Registry . . . . . . . . 8
7.1.1. Registration template . . . . . . . . . . . . . . . . 8
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7.1.2. Initial Registry content . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
8.1. Normative References . . . . . . . . . . . . . . . . . . 12
8.2. Informative References . . . . . . . . . . . . . . . . . 14
Appendix A. Test Vectors . . . . . . . . . . . . . . . . . . . . 14
Appendix B. Implementations . . . . . . . . . . . . . . . . . . 14
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 15
Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction
Signature Agents are entities that originate or forward signed HTTP
requests on behalf of users or services. They include bots
developers, platforms providers, and other intermediaries using
[DIRECTORY]. These agents often need to identify themselves, and
establish trust with origin servers.
Today, the mechanisms for doing so are inconsistent: some rely on
User-Agent strings (e.g. MyCompanyBot/1.0), others on IP address
lists hosted on file servers (e.g. badbots.com), and still others on
out-of-band definitions (e.g. documentation on docs.example.com/
mybot). This diversity makes it difficult for operators and origin
servers to reliably discover and share a Signature Agent’s purpose,
contact information, or rate expectations. Existing discovery
mechanisms, such as [OPENID-CONNECT-DISCOVERY], do not have the
necessary granularity, and pursue different goals.
This document introduces a JSON-based "Signature Agent Card" format
for Signature Agents, to be published in registries and discovered by
servers. It also creates a new IANA registry of "Signature Agent
Card Parameters" to ensure extensibility and consistency of future
attributes.
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. Signature Agent Card
Signature-Agent header is defined in Section 4.1 of [DIRECTORY].
This section describes Signature Agent Card, a JSON object containing
parameters describing the Signature Agent.
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{
"name": "Example Bot",
"contact": "bot-support@example.com",
"logo": "https://example.com/",
"expected-user-agent": "Mozilla/5.0 ExampleBot",
"rfc9309-product-token": "ExampleBot",
"rfc9309-compliance": ["User-Agent", "Allow", "Disallow", "Content-Usage"],
"trigger": "fetcher",
"purpose": "tdm",
"targeted-content": "Cat pictures",
"rate-control": "429",
"rate-expectation": "avg=10rps;max=100rps",
"known-urls": ["/", "/robots.txt", "*.png"],
"keys": {
"kty": "OKP",
"crv": "Ed25519",
"kid": "NFcWBst6DXG-N35nHdzMrioWntdzNZghQSkjHNMMSjw",
"x": "JrQLj5P_89iXES9-vFgrIy29clF9CC_oPPsw3c5D0bs",
"use": "sig",
"nbf": 1712793600,
"exp": 1715385600
}
}
Unless otherwise specified, all parameters in this document are
OPTIONAL. Unknown parameters MUST be ignored. All string values are
UTF-8.
3.1. Name
The name parameter provides a friendly identifier for the Signature
Agent.
Example
* ExampleBot
* My remote browser company
3.2. Contact
The contact parameter provides an email address or reliable
communication channel.
Example * bot-support@example.com * https://example.com/contact
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3.3. Logo
The logo parameter provides an image reference for visual
identification.
Example
* data:image/svg+xml;base64,deadbeef
* https://example.com/logo.png
3.4. Expected user agent
The expected-user-agent parameter specifies one or more User-Agent
strings as defined in Section 10.1.5 of [HTTP] or prefix matches.
Prefixes MAY use * as a wildcard.
Example
* Mozilla/5.0 ExampleBot
3.5. robots.txt product token
The rfc9309-product-token parameter specifies the product token used
for robots.txt directives per Section 2.2.1 of [ROBOTSTXT].
Example
* ExampleBot
3.6. robots.txt compliance
The rfc9309-compliance parameter lists directives from robots.txt
that the agent implements.
Example
* ["User-Agent", "Disallow"]
* ["User-Agent", "Disallow", "CrawlDelay"]
3.7. Trigger
The trigger parameter indicates the operational mode of the agent.
Valid values:
1. "fetcher" - request initiated by the user
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2. "crawler" - autonomous scanning
3.8. Purpose
The purpose parameter describes the intended use of collected data.
Values SHOULD be drawn from a controlled vocabulary, such as
[AIPREF-VOCAB].
Example
* search
* tdm
3.9. Targeted content
The targeted-content parameter specifies the type of data the agent
seeks.
Example
* SEO analysis
* Vulnerability scanning
* Ads verification
3.10. Rate control
The rate-control parameter indicates how origins can influence the
agent’s request rate.
TODO: specify a format
Example
* CrawlDelay in robots.txt (non-standard)
* Custom tool
* 429 + [RATELIMIT-HEADER]
3.11. Rate expectation
The rate-expectation parameter specifies anticipated request volume
or burstiness.
TODO: consider a format such as avg=10rps;max=100rps
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Example
* 500 rps
* Spikes during reindexing
3.12. Known URLs
The known-urls parameter lists predictable endpoints accessed by the
agent.
Example
* /
* /ads.txt
* /favicon.ico
* /index.html
3.13. Keys
The keys parameter contains a JWKS as defined in Section 5 of [JWK].
If keys is present, it is RECOMMENDED that the card is signed using
[HTTP-MESSAGE-SIGNATURES]. Content-Digest header MUST be included in
the covered components.
TODO: describe signature, CWS keys.
Example
* https://example.com/.well-known/http-message-signatures-directory
* JWKS-directory
4. Discovery
Discovery is done via a registry. A registry is a list of URLs, each
one pointing to a signature card.
URLS can be:
* https
* http
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* data
Example
https://bot1.example.com/.well-known/signature-agent-card
https://crawler2.example.com/.well-known/signature-agent-card
https://zerotrust-gateway.example.com/.well-known/signature-agent-card
data:application/json;,...
4.1. Out-of-band communication between client and origin
A service submitting their key to an origin, or the origin manually
adding a service to their trusted list.
4.1.1. Public list
Could be a GitHub repository like the public suffix list. The issue
is the gating of such repositories, and therefore its governance.
4.1.2. Signature-Agent-Card header
This allows for backward compatibility with existing header agent
filtering, and an upgrade to a cryptographically secured protocol.
5. Security Considerations
Malicious actors may put properties which are not theirs in the
registry. Client SHOULD verify signature if they are present.
6. Privacy Considerations
TODO
7. IANA Considerations
7.1. Signature Agent Card Parameters Registry
IANA is requested to create a new "Signature Agent Card Parameters"
registry in a new "Signature Agent Card" page to list metadata for
signature agent protocols.
7.1.1. Registration template
New registrations need to list the following attributes:
*Parameter Name:* The name requested (e.g. "useragent"). This name
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is case sensitive. Names may not match other registered names in
a case-insensitive manner unless the Designated Experts state that
there is a compelling reason to allow an exception
*Parameter Description:* Brief description of the Header Parameter
*Change Controller:* For Standards Track RFCs, list the "IESG". For
others, give the name of the responsible party. Other details
(e.g., postal address, email address, home page URI) may also be
included.
*Reference:* Where this parameter is defined
*Notes:* Any notes associated with the entry
New entries in this registry are subject to the Specification
Required registration policy ([RFC8126], Section 4.6). Designated
experts need to ensure that the token type is defined to be used for
both token issuance and redemption. Additionally, the experts can
reject registrations on the basis that they do not meet the security
and privacy requirements defined in TODO.
7.1.2. Initial Registry content
This section registers the Signature Agent Card Parameter names
defined in Section 3 in this registry.
7.1.2.1. Name Parameter
*Parameter Name:* name
*Parameter Description:* A friendly name for your signature agent.
*Change Controller:* IETF
*Reference:* Section 3.1
*Notes:* N/A
7.1.2.2. Contact Parameter
*Parameter Name:* contact
*Parameter Description:* Email or any other reliable communication
channel
*Change Controller:* IETF
*Reference:* Section 3.2
*Notes:* N/A
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7.1.2.3. Logo Parameter
*Parameter Name:* logo
*Parameter Description:* Image for a quick visual identification
*Change Controller:* IETF
*Reference:* Section 3.3
*Notes:* N/A
7.1.2.4. Expected User Agent Parameter
*Parameter Name:* expected-user-agent
*Parameter Description:* String or fragment patterns
*Change Controller:* IETF
*Reference:* Section 3.4
*Notes:* N/A
7.1.2.5. RFC9309 Product Token Parameter
*Parameter Name:* rfc9309-product-token
*Parameter Description:* Robots.txt product token your signature-
agent satisfies.
*Change Controller:* IETF
*Reference:* Section 3.5
*Notes:* N/A
7.1.2.6. RFC9309 Compliance Parameter
*Parameter Name:* rfc9309-compliance
*Parameter Description:* Does your signature-agent respect
robots.txt.
*Change Controller:* IETF
*Reference:* Section 3.6
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*Notes:* N/A
7.1.2.7. Trigger Parameter
*Parameter Name:* trigger
*Parameter Description:* Fetcher/Crawler
*Change Controller:* IETF
*Reference:* Section 3.7
*Notes:* N/A
7.1.2.8. Purpose Parameter
*Parameter Name:* purpose
*Parameter Description:* Intended use for the collected data
*Change Controller:* IETF
*Reference:* Section 3.8
*Notes:* N/A
7.1.2.9. Targeted Content Parameter
*Parameter Name:* targeted-content
*Parameter Description:* Type of data your agent seeks
*Change Controller:* IETF
*Reference:* Section 3.9
*Notes:* N/A
7.1.2.10. Rate control Parameter
*Parameter Name:* rate-control
*Parameter Description:* How can an origin control your crawl rate
*Change Controller:* IETF
*Reference:* Section 3.10
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*Notes:* N/A
7.1.2.11. Rate expectation Parameter
*Parameter Name:* rate-expectation
*Parameter Description:* Expected traffic and intensity
*Change Controller:* IETF
*Reference:* Section 3.11
*Notes:* N/A
7.1.2.12. Known URLs Parameter
*Parameter Name:* known-urls
*Parameter Description:* Predictable endpoint accessed
*Change Controller:* IETF
*Reference:* Section 3.12
*Notes:* N/A
7.1.2.13. Keys Parameter
*Parameter Name:* keys
*Parameter Description:* JWKS Endpoint
*Change Controller:* IETF
*Reference:* Section 3.13
*Notes:* N/A
8. References
8.1. Normative References
[AIPREF-VOCAB]
Keller, P. and M. Thomson, "A Vocabulary For Expressing AI
Usage Preferences", Work in Progress, Internet-Draft,
draft-ietf-aipref-vocab-03, 4 September 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-aipref-
vocab-03>.
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[DIRECTORY]
Meunier, T., "HTTP Message Signatures Directory", Work in
Progress, Internet-Draft, draft-meunier-http-message-
signatures-directory-03, 5 September 2025,
<https://datatracker.ietf.org/doc/html/draft-meunier-http-
message-signatures-directory-03>.
[HTTP] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Semantics", STD 97, RFC 9110,
DOI 10.17487/RFC9110, June 2022,
<https://www.rfc-editor.org/rfc/rfc9110>.
[HTTP-CACHE]
Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Caching", STD 98, RFC 9111,
DOI 10.17487/RFC9111, June 2022,
<https://www.rfc-editor.org/rfc/rfc9111>.
[HTTP-MESSAGE-SIGNATURES]
Backman, A., Ed., Richer, J., Ed., and M. Sporny, "HTTP
Message Signatures", RFC 9421, DOI 10.17487/RFC9421,
February 2024, <https://www.rfc-editor.org/rfc/rfc9421>.
[HTTP-MORE-STATUS-CODE]
Nottingham, M. and R. Fielding, "Additional HTTP Status
Codes", RFC 6585, DOI 10.17487/RFC6585, April 2012,
<https://www.rfc-editor.org/rfc/rfc6585>.
[JWK] Jones, M., "JSON Web Key (JWK)", RFC 7517,
DOI 10.17487/RFC7517, May 2015,
<https://www.rfc-editor.org/rfc/rfc7517>.
[JWK-OKP] Liusvaara, I., "CFRG Elliptic Curve Diffie-Hellman (ECDH)
and Signatures in JSON Object Signing and Encryption
(JOSE)", RFC 8037, DOI 10.17487/RFC8037, January 2017,
<https://www.rfc-editor.org/rfc/rfc8037>.
[JWK-THUMBPRINT]
Jones, M. and N. Sakimura, "JSON Web Key (JWK)
Thumbprint", RFC 7638, DOI 10.17487/RFC7638, September
2015, <https://www.rfc-editor.org/rfc/rfc7638>.
[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>.
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[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/rfc/rfc8126>.
[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>.
8.2. Informative References
[OAUTH-BEARER]
Jones, M. and D. Hardt, "The OAuth 2.0 Authorization
Framework: Bearer Token Usage", RFC 6750,
DOI 10.17487/RFC6750, October 2012,
<https://www.rfc-editor.org/rfc/rfc6750>.
[OPENID-CONNECT-DISCOVERY]
"OpenID Connect Discovery 1.0", n.d.,
<https://openid.net/specs/openid-connect-discovery-
1_0.html>.
[RATELIMIT-HEADER]
Polli, R., Ruiz, A. M., and D. Miller, "RateLimit header
fields for HTTP", Work in Progress, Internet-Draft, draft-
ietf-httpapi-ratelimit-headers-09, 17 March 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-httpapi-
ratelimit-headers-09>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/rfc/rfc8446>.
[ROBOTSTXT]
Koster, M., Illyes, G., Zeller, H., and L. Sassman,
"Robots Exclusion Protocol", RFC 9309,
DOI 10.17487/RFC9309, September 2022,
<https://www.rfc-editor.org/rfc/rfc9309>.
Appendix A. Test Vectors
TODO
Appendix B. Implementations
TODO
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Acknowledgments
TODO
The editor would also like to thank the following individuals (listed
in alphabetical order) for feedback, insight, and implementation of
this document -
Changelog
v00
* Initial draft
Authors' Addresses
Maxime Guerreiro
Cloudflare
Email: maxime.guerreiro@gmail.com
Thibault Meunier
Cloudflare
Email: ot-ietf@thibault.uk
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