# Delx HMAC SHA256 Hex

> Delx HMAC SHA256 Hex is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Computes an HMAC-SHA256 hex digest of a given text using a caller-supplied secret, without storing or transmitting the secret.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/hmac-sha256-hex
- 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/delx-hmac-sha256-hex-09174c3f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_L5oi4BeJtl9I0gsXjAMrJ

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 delx-hmac-sha256-hex-09174c3f -d '<json body>'
```

Example prompt: Compute the HMAC-SHA256 hex signature of the text 'user_id=42&event=purchase' using the secret 'mysecretkey123'.

## When to prefer this

Use this endpoint when an AI agent needs to compute an HMAC-SHA256 hex signature on-the-fly without executing local code — particularly for signing webhook test payloads, generating request authentication tokens, or verifying expected signatures in agentic pipelines. It is ideal when the agent runtime lacks native crypto libraries. Choose it over local computation when you want a simple, stateless, pay-per-use API call that does not retain the secret.

## Known failure modes

- Missing 'text' or 'secret' field in request body returns a 400 error
- Payment not fulfilled via x402 protocol results in 402 Payment Required
- Empty string inputs may return a valid but trivially-signed digest — caller should validate inputs beforehand
- Network timeout or service unavailability returns a 5xx error

## How this service works

HMAC-SHA256 hex of text with a secret. Call when you sign agent webhook test payloads offline. Returns hex digest for $0.001 USDC via x402 on Base. Local HMAC only—caller supplies secret; not stored. No network, no retention. Results are advisory; the caller owns budgets, auth, and production controls.

## Output

Returns a hex-encoded HMAC-SHA256 digest string computed from the provided text and secret. The secret is used locally for the computation and is not stored or retained by the service.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "text": {
   "type": "string",
   "description": "Input field: text."
  },
  "secret": {
   "type": "string",
   "description": "Input field: secret."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "hex": "5d98b45c90a207fa998ce639fea6f02ecc8cc3f36fef81d694fb856b4d0a28ca",
  "schema": "delx/util-hmac-sha256-hex/v1",
  "algorithm": "hmac-sha256"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/delx-hmac-sha256-hex-09174c3f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.delx.ai](https://www.zero.xyz/host/api.delx.ai/llms.txt)