# util.beauty HMAC Crypto Utility

> util.beauty HMAC Crypto Utility is a paid API for AI agents from util.beauty, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Computes HMAC (Hash-based Message Authentication Code) signatures for a given message and secret key via a metered pay-per-use API.

## Facts

- Endpoint: POST https://util.beauty/v1/crypto/hmac
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/util-beauty-hmac-crypto-utility-dc1cbc30
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_wGxPyo5HobUwuXQnzs4a8

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 util-beauty-hmac-crypto-utility-dc1cbc30 -d '<json body>'
```

Example prompt: Compute an HMAC-SHA256 signature for the message 'order:12345:confirmed' using the secret key 'mySecretKey2024' so I can attach it as a webhook signature header.

## When to prefer this

Choose this endpoint when your agent needs a quick, pay-per-use HMAC computation without setting up a local crypto library or managing dependencies — ideal for serverless agents, low-volume use cases billed per request via USDC on Base (x402), or when you need a metered, auditable crypto utility call with a request ID for tracing.

## Known failure modes

- Missing or invalid secret key returns an error response with ok:false
- Unsupported hashing algorithm returns a 400-level error
- Insufficient credits or payment failure returns a 402 Payment Required
- Malformed request body causes a validation error
- Empty or null message input may result in a processing error

## How this service works

Metered web utilities for developers and AI agents: browser screenshot and PDF, crypto, DNS and net tools. Pay per request with x402 (USDC on Base) or prepaid API keys.

## Output

Returns a JSON object containing a boolean 'ok' status, the utility name, a unique requestId for tracing, the HMAC computation result (the MAC digest), and the number of credits charged for the call.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "properties": {
  "input": {
   "type": "object",
   "properties": {
    "body": {
     "type": "object",
     "description": "JSON request body (see OpenAPI for the utility schema).",
     "additionalProperties": true
    }
   }
  },
  "output": {
   "type": "object",
   "properties": {
    "example": {
     "type": "object",
     "properties": {
      "ok": {
       "type": "boolean"
      },
      "utility": {
       "type": "string"
      },
      "requestId": {
       "type": "string"
      },
      "chargedCredits": {
       "type": "number"
      }
     },
     "additionalProperties": true
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "utility": "…",
  "requestId": "req_…",
  "chargedCredits": 1
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/util-beauty-hmac-crypto-utility-dc1cbc30/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from util.beauty](https://www.zero.xyz/host/util.beauty/llms.txt)