# Web Bot Auth

> Cryptographically proves which agent is making a request via HTTP Message Signatures — because a User-Agent string can be forged and a signature cannot.

_The Agent Protocol Atlas · /protocols/web-bot-auth · [JSON](/api/protocols/web-bot-auth) · [all The Agent Protocol Atlas](/protocols)_

- **name:** Web Bot Auth
- **full_name:** Web Bot Authentication (HTTP Message Signatures)
- **layer:** identity
- **creator:** IETF drafts, championed by Cloudflare
- **status:** emerging
- **year:** 2025
- **one_liner:** Cryptographically proves which agent is making a request via HTTP Message Signatures — because a User-Agent string can be forged and a signature cannot.
- **spec_url:** https://datatracker.ietf.org/doc/draft-meunier-web-bot-auth-architecture/
- **snippet:**

```
Signature-Agent: "https://my-agent.example"
Signature-Input: sig1=("@authority" "signature-agent");keyid="..."
```
- **abbreviation:** Web Bot Auth
- **also_known_as:** Web Bot Authentication, HTTP Message Signatures for bots, Signature Agent
- **canonical_spec_url:** https://datatracker.ietf.org/doc/html/draft-meunier-web-bot-auth-architecture-02
- **entity_uri:** https://datatracker.ietf.org/doc/draft-meunier-web-bot-auth-architecture/
- **taxonomy_layer:** identity
- **sub_layer:** request-signing
- **protocol_type:** verification
- **central_problem:** Lets a server cryptographically verify which agent is making an HTTP request, since a User-Agent string can be forged and an Ed25519 signature cannot.
- **maintainer:** IETF (draft-meunier-web-bot-auth-architecture), championed by Cloudflare
- **governance_body:** IETF
- **license:** IETF Trust (RFC / Internet-Draft terms)
- **maturity_tag:** emerging
- **current_spec_version:** draft-meunier-web-bot-auth-architecture-02
- **spec_date:** — (verify-against-primary-at-build)
- **launch_date:** 2025
- **last_verified:** 2026-06-15
- **transport:** HTTP message signatures (RFC 9421), Ed25519 keys; Signature-Agent header
- **core_mechanism:** Built on RFC 9421 HTTP Message Signatures with Ed25519 keys: the agent signs covered components (e.g. @authority and signature-agent) and advertises its public keys as a JWKS at /.well-known/http-message-signatures-directory; the server fetches that directory and verifies the signature to confirm the agent's identity.
- **discovery_endpoint:** /.well-known/http-message-signatures-directory (JWKS) + Signature-Agent header
- **settlement_type:** —
- **adoption_metric:** — (verify-against-primary-at-build)
- **notable_adopters:** {"value":"Cloudflare (champion + reference implementation)","source":"https://datatracker.ietf.org/doc/draft-meunier-web-bot-auth-architecture/"}
- **relationships:** {"predicate":"verifies","target":"x402","note":"Web Bot Auth can verify the agent identity behind a paid request."}, {"predicate":"verifies","target":"rsl","note":"Web Bot Auth -verifies-> pay-per-crawl-class enforcement (research §2 seed triple: 'Web Bot Auth verifies pay-per-crawl'); RSL/pay-per-crawl licensing relies on knowing which agent is real."}
- **ideal_use_case:** Letting a site trust that a request claiming to be ClaudeBot/GPTBot really is that agent before granting access or charging it.
- **when_to_use:** When you must verify agent identity for access control, licensing enforcement, or paid crawling — not just read a forgeable User-Agent string.
- **when_not_to_use:** When you only need to declare content to agents (Layer-1 discovery) and don't gate or charge access by identity.
- **code_example:** Signature-Agent: "https://my-agent.example"
Signature-Input: sig1=("@authority" "signature-agent");keyid="...";alg="ed25519"
Signature: sig1=:<base64 ed25519 signature>:
- **source:** RFC 9421 + Ed25519 + Signature-Agent header + /.well-known/http-message-signatures-directory: https://datatracker.ietf.org/doc/html/draft-meunier-web-bot-auth-architecture-02 ; Cloudflare reference: https://http-message-signatures-example.research.cloudflare.com/ ; research §1.
- **agent_readiness_link:** agent-readiness/web-bot-auth