Name: Agent Identity Verification (RFC 9421 Web Bot Auth)
Author: Post Oak Labs

1ROOT · D0node

Web Bot Auth Signature Verifier (RFC 9421) art-129

Signature verdict feeds directory validation

MCP Call · verify_webbotauth_signature

{
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "name": "verify_webbotauth_signature",
    "arguments": {
      "covered_components": [
        { "name": "method", "value": "POST" },
        { "name": "@authority", "value": "api.example.com" },
        { "name": "@path", "value": "/agent/v1/execute" }
      ],
      "signature_params": "(\"method\" \"@authority\" \"@path\");created=1750000000;keyid=\"key-2026-06\";tag=\"web-bot-auth\";alg=\"ed25519\"",
      "signature_b64": "ruUab1uVdHazfuOcU0E4qLcTnOM2Z7zYHiluP5qxDZkKbw8EjPNarFHL7G2fS2DhnFH1xlpbihrIkOm8jwxIDA==",
      "public_key_jwk": { "kty": "OKP", "crv": "Ed25519", "x": "WrHvnND7oaWfvrGxUU3FNeJaQDwYj4K3e5fl0fH5p2g" },
      "alg": "ed25519",
      "expected_tag": "web-bot-auth",
      "created": 1750000000,
      "now_unix": 1750003600,
      "max_age_s": 3600
    }
  },
  "id": 1
}

2MIDDLE · D1node

HTTP Signatures Directory Validator art-130

Directory validation feeds agent card check

MCP Call · validate_signature_directory

{
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "name": "validate_signature_directory",
    "arguments": {
      "well_known_path": "/.well-known/http-message-signatures-directory",
      "keyid": "key-2026-06",
      "directory_jwks": {
        "keys": [
          {
            "kty": "OKP",
            "crv": "Ed25519",
            "kid": "key-2026-06",
            "x": "WrHvnND7oaWfvrGxUU3FNeJaQDwYj4K3e5fl0fH5p2g"
          }
        ]
      }
    }
  },
  "id": 2
}

3TERMINAL · D2node

Signature Agent Card Validator art-131

Exports identity-trust verdict with execution_hash — final stage

MCP Call · validate_signature_agent_card

{
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "name": "validate_signature_agent_card",
    "arguments": {
      "card": {
        "name": "TradeAgent-v1",
        "operator": "Acme Corp",
        "expected_request_rate": 100,
        "keys": [{ "kid": "key-2026-06" }]
      },
      "directory_keyids": ["key-2026-06", "key-2026-07-next"]
    }
  },
  "id": 3
}