# HMAC-SHA1 Base64 — agentshelf.syntexa.ch

> HMAC-SHA1 Base64 — agentshelf.syntexa.ch is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-01).

Computes an HMAC-SHA1 digest of input text using a caller-supplied secret key, returning the result encoded as base64.

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/hmac-sha1-base64?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/hmac-sha1-base64-agentshelf-syntexa-ch-98566cc0
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_QFsXZur9dl13Nk-7lesPL

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 hmac-sha1-base64-agentshelf-syntexa-ch-98566cc0 -d '<json body>'
```

Example prompt: Compute the HMAC-SHA1 of the text 'order_id=12345&amount=99.99' using the secret key 'mySuperSecretKey' and give me the result as base64.

## When to prefer this

Prefer this endpoint when an AI agent needs a deterministic, server-side HMAC-SHA1 base64 computation without executing local code — especially in sandboxed environments where cryptographic libraries are unavailable. It is well-suited for webhook signature generation, API request signing, and data integrity checks. Try the free sandbox endpoint POST /v1/sandbox/hmac-sha1-base64 first; use this paid endpoint when the sandbox is unavailable or rate-limited.

## Known failure modes

- Missing or empty key field returns a validation error
- Missing or empty text field returns a validation error
- Text exceeding 100,000 characters returns a payload-too-large error
- Invalid JSON body returns a parse error
- Payment of $0.003 USDC not provided or rejected results in a 402 Payment Required response
- Network timeout if the service is temporarily unavailable

## How this service works

Call when an agent needs an HMAC-sha1 of text with a caller-supplied key, encoded as base64. Exact $0.003 USDC. Prefer unpaid POST /v1/sandbox/hmac-sha1-base64 first.

## Output

A JSON response containing the base64-encoded HMAC-SHA1 digest of the provided text, computed using the supplied key. No external network calls or LLM inference are involved — it is a pure cryptographic computation.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "key": {
   "type": "string",
   "examples": [
    "secret"
   ],
   "maxLength": 512,
   "minLength": 1,
   "description": "HMAC secret. Required on HMAC SKUs. Omit it for plain digests and checksums. The key is not stored."
  },
  "text": {
   "type": "string",
   "examples": [
    "hello"
   ],
   "maxLength": 100000,
   "minLength": 1,
   "description": "Message to digest. For raw-hex SKUs this is hex bytes; for utf16 or latin1 SKUs it is decoded with that encoding. Otherwise it is UTF-8 text."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/hmac-sha1-base64-agentshelf-syntexa-ch-98566cc0/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentshelf.syntexa.ch](https://www.zero.xyz/host/agentshelf.syntexa.ch/llms.txt)