# SHAKE-128 Hex Digest

> SHAKE-128 Hex Digest is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-01).

Computes a SHAKE128 (extendable-output function) digest of input text and returns the result encoded as a hexadecimal string.

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/digest-shake128-hex?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/shake-128-hex-digest-7270fc88
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_0kcatqx-rGcJOeNhuM6Kb

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 shake-128-hex-digest-7270fc88 -d '<json body>'
```

Example prompt: Can you compute the SHAKE128 hex digest of the text 'Hello, world!' using the key 'mykey123'?

## When to prefer this

Choose this endpoint when you need a SHAKE128 (extendable-output function) digest specifically encoded as hexadecimal. Use the free sandbox endpoint POST /v1/sandbox/digest-shake128-hex first for testing. Prefer this over SHA-2 or SHA-3 endpoints when an XOF (variable-length output) is required. Choose hex encoding over base64/base32 siblings when downstream systems expect hex format.

## Known failure modes

- Empty or missing text/key fields return a validation error
- Text exceeding 100,000 characters is rejected
- Key exceeding 512 characters is rejected
- Payment not provided or insufficient USDC results in HTTP 402 Payment Required
- Malformed JSON body returns 400 Bad Request

## How this service works

Call when an agent needs a shake128 digest of text, encoded as hex. No network and no LLM. Exact $0.001 USDC. Prefer unpaid POST /v1/sandbox/digest-shake128-hex first.

## Output

Returns a hexadecimal string representing the SHAKE128 (XOF) digest of the provided input text. The output length is determined by the key parameter. No network calls or LLM inference are involved — the computation is purely deterministic and local.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "key": {
   "type": "string",
   "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/shake-128-hex-digest-7270fc88/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)