# agentshelf.syntexa.ch BLAKE2b-512 Hex Digest

> agentshelf.syntexa.ch BLAKE2b-512 Hex Digest is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-01).

Computes a BLAKE2b-512 cryptographic hash of input text and returns it as a lowercase hexadecimal string.

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/digest-blake2b512-hex?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agentshelf-syntexa-ch-blake2b-512-hex-digest-538ce6ff
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_bR5KS4mwtl_W6DrUCPGDn

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 agentshelf-syntexa-ch-blake2b-512-hex-digest-538ce6ff -d '<json body>'
```

Example prompt: Can you compute the BLAKE2b-512 hex hash of the text 'Hello, world!' — no key needed?

## When to prefer this

Choose this endpoint when you need a BLAKE2b-512 hash specifically encoded as hexadecimal (e.g. for storage in hex columns, comparison with other hex hashes, or tooling that expects hex). Prefer the free sandbox endpoint POST /v1/sandbox/digest-blake2b512-hex first for testing. Use the base64url sibling endpoint if you need a more compact encoding. Choose BLAKE2b-512 over MD5 or SHA-224 when you need a stronger, collision-resistant hash with optional keying (MAC) capability.

## Known failure modes

- Empty or missing 'text' field returns a validation error
- Key length exceeds 512 characters returns a validation error
- Text exceeds 100,000 characters returns a size limit error
- Malformed JSON body returns a 400 error
- Payment failure or insufficient USDC balance returns a 402 error

## How this service works

Call when an agent needs a blake2b512 digest of text, encoded as hex. No network and no LLM. Exact $0.005 USDC. Prefer unpaid POST /v1/sandbox/digest-blake2b512-hex first.

## Output

Returns a 128-character lowercase hexadecimal string representing the BLAKE2b-512 digest of the input text. If a key is provided, the result is a keyed (MAC-style) hash. The computation is performed entirely server-side with no external network calls or LLM inference.

## 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/agentshelf-syntexa-ch-blake2b-512-hex-digest-538ce6ff/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)