How do I sign my own AI agent's HTTP requests with Web Bot Auth so websites can verify it?

What should I check, step by step?

1. Generate a dedicated Ed25519 key for the agent (Cloudflare's docs use openssl genpkey -algorithm ed25519). Keep the private key in a secret store, one key per agent or environment, and never reuse a TLS or code-signing key.

2. Publish a JWKS with the public key (kty OKP, crv Ed25519, x) at https://<your domain>/.well-known/http-message-signatures-directory, served with Content-Type application/http-message-signatures-directory+json. Never include the private d parameter.
3. Sign the directory response itself: one signature per key, tag="http-message-signatures-directory", keyid = that key's thumbprint, covering "@authority";req. Cloudflare says this stops anyone mirroring your directory and registering it as theirs.
4. Compute the keyid as the base64url JWK SHA-256 thumbprint (RFC 7638; for Ed25519 the OKP form in RFC 8037). If you put a kid in the JWKS, the draft says it must equal that thumbprint.
5. On each request, cover at least @authority and signature-agent, plus @method and @path if you want the signature to fit one request only. Set created, a short expires (Cloudflare suggests a minute is often enough; the draft recommends no more than 24 hours) and a fresh nonce.
6. Choose the Signature-Agent form per verifier: a quoted string such as "https://agent.example.com" for Cloudflare today, the dictionary form sig1="https://..." for verifiers that follow the current draft. Don't add parameters to dictionary members; the draft says verifiers must ignore a member that carries them.
7. Sign only ASCII components, and don't sign Content-Digest if a proxy might change the body. Cloudflare fails @query-params, @status and the sf, bs, key and req parameters on request components.
8. Register with the verifiers you need (Cloudflare: BotBase submission form, Verification Method = Request Signature, your directory URL), then test: crawltest.com/cdn-cgi/web-bot-auth returns 401 for a well-formed request with an unknown key, 200 when the key is known and the signature verifies, 400 otherwise.
9. Rotate by publishing the new key next to the old one, switching signing, then removing the old key once in-flight signatures have expired.

What does a Web Bot Auth signature prove to a website about an AI agent?

A user-agent string is text anyone can send. A valid Web Bot Auth signature shows the request was signed by a key published at the Signature-Agent URL, so a site can allowlist, rate limit or block that signer without relying on IP ranges. Cloudflare's verified bots page says signed agents have been counted as Verified since July 1, 2026, labelled Direct (one operator) or Intermediary (a service many end users drive).

• It doesn't prove the agent is well behaved. Cloudflare's second bar for Verified status is behaviour: obey robots.txt and crawl directives, keep request rates reasonable, don't evade site owner preferences. A signature makes your agent accountable for what it does, which is the point.
• The draft also warns that a signature covering only @authority is valid for any method, path or body sent to that site until it expires, so anyone who sees one request can reuse it there. Short expiry and covering @method and @path narrow that.

What is the status of the Web Bot Auth standard and its Signature-Agent header format?

The IETF webbotauth working group adopted the protocol as draft-ietf-webbotauth-httpsig-protocol (revision 01, October 29, 2026). It replaced the individual drafts Cloudflare's docs still cite, and it is still a draft, so details can change.

• The main incompatibility today is the Signature-Agent header: Cloudflare implements the older quoted-string form from draft-meunier-http-message-signatures-directory-03; the WG draft requires signers to send a dictionary keyed by signature label. Pick per destination until verifiers converge, and re-test when either side updates.
• Not every operator can host a directory. draft-singh-webbotauth-hosted-directories-00 (July 2026) discusses directories a registry hosts for many agents, and notes that a host must not hold tenants' private keys, so it can't sign the directory response the way a self-hosted one can. Some verifiers, including Cloudflare's registration, expect the signed self-hosted form.

How do I test that my AI agent's signed requests verify before rollout?

Capture one real outgoing request (method, URL and the three signature headers exactly as sent) and run it through each verifier you care about: Cloudflare's crawltest endpoint, your own middleware, and gate_check.

• gate_check resolves your Signature-Agent URL over HTTPS (no redirects), picks the key by thumbprint, verifies the signature and checks it was made for the site's domain, then answers allow or deny with reasons such as an expired signature or a directory it couldn't fetch. It accepts both the quoted-string and dictionary forms of Signature-Agent.