# Holoweave Witness WBA Signature Verifier

> Holoweave Witness WBA Signature Verifier is a paid API for AI agents from witness.holoweave.org, paid per call via x402, $0.01/call, status down (last checked 2026-09-15).

Verifies that an HTTP request's Ed25519 signature (RFC 9421) is valid against the agent's published key directory

## Facts

- Endpoint: POST https://witness.holoweave.org/v1/wba-signature
- Price: $0.01/call
- Payment: x402
- Status: down
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/holoweave-witness-wba-signature-verifier-f0ebe4d8
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_pS-7cv1yo75raaj7Oppan

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability holoweave-witness-wba-signature-verifier-f0ebe4d8 -d '<json body>'
```

Example prompt: Can you verify that this signed HTTP POST to https://api.example.com/data — with the Signature-Input, Signature, and Signature-Agent headers I generated — actually validates against my published JWKS at https://agent.example.com/.well-known/jwks.json using Ed25519?

## When to prefer this

Use this endpoint when you need to verify RFC 9421 HTTP message signatures using Ed25519, particularly in WBA (Web Browsing Agent) authentication flows. Prefer it over general-purpose JWT or OAuth verifiers when working with HTTP message signatures rather than bearer tokens. Especially useful for agents that self-sign HTTP requests and need to validate their own signatures before sending, or debug why a server is rejecting their signed requests. The sibling endpoint on witness.holoweave.org handles key thumbprint/keyid resolution (RFC 7638); use this one specifically when you have a full signed request and want end-to-end signature verification.

## Known failure modes

- Key not found in directory — the keyid in the Signature-Input does not match any key in the JWKS
- Signature mismatch — the signature does not cryptographically verify against the resolved key
- Malformed Signature-Input — the signature base cannot be constructed from the provided headers
- Invalid JWKS URI — the key_directory URL is unreachable or returns an invalid JWKS
- Missing required headers — Signature-Input or Signature header absent from the request sample
- Unsupported algorithm — key type or algorithm is not Ed25519 as expected

## How this service works

Web bot auth debugging for AI agents, priced per check at $0.01. RFC 7638 keyid thumbprint verification, RFC 9421 Ed25519 signature verification, and per-verifier acceptance rules. Signed attestations, published fixtures, sources with dates.

## Output

A response indicating whether the Ed25519 signature on the provided HTTP request successfully verifies against the agent's published JWKS key directory, based on the RFC 9421 signature base constructed from the URL, method, and headers (including Signature-Input and Signature). Returns validity status and likely details about any verification failure.

## Response schema (JSON Schema)

```json
{
 "example": {
  "signature": {
   "alg": "ed25519",
   "value": "base64...",
   "key_id": "aw-attest-2026-08"
  },
  "attestation": {
   "verdict": "fail",
   "endpoint": "wba-signature",
   "evidence": {
    "results": {
     "sig1": {
      "reason": "key_not_selectable",
      "verified": null
     }
    }
   },
   "findings": [
    {
     "code": "SIG_KEY_NOT_SELECTABLE",
     "detail": "keyid is the kid, not the RFC 7638 thumbprint, so the signature was never tested.",
     "severity": "blocking"
    }
   ]
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/holoweave-witness-wba-signature-verifier-f0ebe4d8/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from witness.holoweave.org](https://www.zero.xyz/host/witness.holoweave.org/llms.txt)