# GoldKey Guard EVM Transaction Authorization

> GoldKey Guard EVM Transaction Authorization is a paid API for AI agents from goldkey-edge-storefront.noah-ing.workers.dev, paid per call via x402, $0.1/call, status unknown (last checked 2026-09-15).

Authorizes or blocks an EVM blockchain transaction against operator-signed policy and returns a cryptographically signed receipt required before execution proceeds.

## Facts

- Endpoint: POST https://goldkey-edge-storefront.noah-ing.workers.dev/v1/guard/paygo/authorize/evm
- Price: $0.1/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/goldkey-guard-evm-transaction-authorization-27d71dba
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_NAO7zJ9qdZlRSWkL6Bia8

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 goldkey-guard-evm-transaction-authorization-27d71dba -d '<json body>'
```

Example prompt: Before submitting this EIP-1559 transaction — from 0xAbC...123 to 0xDeF...456 on chain 1, with 0 ETH value and this calldata — run it through GoldKey Guard with my installation ID gki_... and idempotency key tx-001, and only proceed if you get back an ALLOW receipt with a valid signature.

## When to prefer this

Use this endpoint when you need a cryptographically signed authorization receipt specifically for EVM blockchain transactions before they execute — especially in AI agent pipelines where auditability, operator-policy enforcement, and non-repudiation of on-chain actions are required. Prefer this over generic policy checks when the call type is an EIP-1559 EVM transaction with chain ID, gas parameters, and calldata, and you need the signed receipt as a gate before broadcasting. Use the sibling MCP/HTTPS endpoint instead for non-EVM tool calls.

## Known failure modes

- Invalid or missing signature on the request body returns 401/403
- Malformed EVM address (not matching ^0x[0-9a-fA-F]{40}$) causes schema validation failure
- Unknown installation_id returns policy-not-found error
- Duplicate idempotency_key with different payload may return conflict error
- Policy decision of BLOCK or REVIEW means the transaction must not proceed
- Payment of 0.1 USDC not included or invalid causes 402 Payment Required
- Expired issued_at timestamp may cause request rejection
- Network/worker failure returns 5xx and no receipt is issued

## How this service works

GoldKey Guard is an execution-path authorization layer for AI agents: operator-signed policy, a customer-controlled local enforcer, and signed receipts before MCP, HTTPS, or supported EVM calls run.

## Output

A JSON envelope (goldkey.guard-authorization-envelope.v1) containing: a decision field (ALLOW, REVIEW, or BLOCK) with reason codes, an evidence object with the same decision and codes, a base64url signature over the receipt, and a SHA-256 hash of the receipt — all required as proof of authorization before the EVM transaction may be submitted.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "call": {
   "oneOf": [
    {
     "type": "object",
     "required": [
      "kind",
      "connector_id",
      "transaction"
     ],
     "properties": {
      "kind": {
       "const": "evm_transaction"
      },
      "transaction": {
       "type": "object",
       "required": [
        "chain_id",
        "from",
        "value_atomic",
        "data",
        "nonce",
        "gas_limit",
        "max_fee_per_gas_atomic",
        "max_priority_fee_per_gas_atomic"
       ],
       "properties": {
        "to": {
         "type": "string",
         "pattern": "^0x[0-9a-fA-F]{40}$"
        },
        "data": {
         "type": "string",
         "pattern": "^0x(?:[0-9a-fA-F]{2})*$"
        },
        "from": {
         "type": "string",
         "pattern": "^0x[0-9a-fA-F]{40}$"
        },
        "type": {
         "const": "eip1559"
        },
        "nonce": {
         "type": "string",
         "pattern": "^(0|[1-9][0-9]{0,77})$"
        },
        "chain_id": {
         "type": "integer",
         "minimum": 1
        },
        "gas_limit": {
         "type": "string",
         "pattern": "^(0|[1-9][0-9]{0,77})$"
        },
        "access_list": {
         "type": "array",
         "maxItems": 0
        },
        "value_atomic": {
         "type": "string",
         "pattern": "^(0|[1-9][0-9]{0,77})$"
        },
        "max_fee_per_gas_atomic": {
         "type": "string",
         "pattern": "^(0|[1-9][0-9]{0,77})$"
        },
        "max_priority_fee_per_gas_atomic": {
         "type": "string",
         "pattern": "^(0|[1-9][0-9]{0,77})$"
        }
       },
       "additionalProperties": false
      },
      "connector_id": {
       "type": "string",
       "pattern": "^[A-Za-z0-9._:-]{1,128}$"
      }
     },
     "additionalProperties": false
    }
   ]
  },
  "schema": {
   "const": "goldkey.guard-request.v1"
  },
  "issued_at": {
   "type": "string",
   "format": "date-time"
  },
  "signature": {
   "type": "string",
   "pattern": "^[A-Za-z0-9_-]{86}$"
  },
  "idempotency_key": {
   "type": "string",
   "pattern": "^[A-Za-z0-9._:-]{8,128}$"
  },
  "installation_id": {
   "type": "string",
   "pattern": "^gki_[A-Za-z0-9_-]{43}$"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "schema": "goldkey.guard-authorization-envelope.v1",
  "receipt": {
   "decision": "ALLOW",
   "reason_codes": []
  },
  "evidence": {
   "schema": "goldkey.guard-evidence.v1",
   "decision": "ALLOW",
   "reason_codes": []
  },
  "signature": "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA",
  "receipt_sha256": "0000000000000000000000000000000000000000000000000000000000000000"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/goldkey-guard-evm-transaction-authorization-27d71dba/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from goldkey-edge-storefront.noah-ing.workers.dev](https://www.zero.xyz/host/goldkey-edge-storefront.noah-ing.workers.dev/llms.txt)