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HMAC-BLAKE2b-512 Hex Digest
x402
HMAC-BLAKE2b-512 Hex Digest is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.009/call, status unknown (last checked 2026-10-02).
Computes an HMAC using the BLAKE2b-512 hash function with a caller-supplied key and returns the result as a lowercase hex string
Price / call$0.009
Success—
StatusUnknown
How this service works
Call when an agent needs an HMAC-blake2b512 of text with a caller-supplied key, encoded as hex. Exact $0.009 USDC. Prefer unpaid POST /v1/sandbox/hmac-blake2b512-hex first.
Output
A hex-encoded HMAC-BLAKE2b-512 string (128 hex characters representing 64 bytes) computed from the supplied text and key. No additional metadata is returned.
Example use cases
Webhook payload integrity signing
“I need to sign this webhook payload 'user_id=42&event=purchase' with my secret key 'wh_secret_abc123' using HMAC-BLAKE2b-512 — can you compute the hex digest so I can attach it to the request?”
API request authentication token
“Generate an HMAC-BLAKE2b-512 hex digest for the string 'GET /api/orders/2024-05-01' using the key 'api_signing_key_xyz' so I can authenticate the API call.”
Data tamper detection checksum
“Compute a keyed HMAC-BLAKE2b-512 hash of this JSON blob '{"amount":500,"currency":"USD"}' with the key 'integrity_key_99' so I can store it alongside the record and verify it hasn't been tampered with.”
Technical details
Endpoint
POSThttps://agentshelf.syntexa.ch/v1/hmac-blake2b512-hex?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a BLAKE2b-512-based HMAC (rather than SHA-256 or SHA-512 HMAC) and want hex output. BLAKE2b is faster than SHA-2 in software and provides equivalent security. Use the free sandbox endpoint POST /v1/sandbox/hmac-blake2b512-hex first to validate your integration before incurring the $0.009 USDC charge.
Side effects
- Missing or empty 'key' field returns a validation error
- Missing or empty 'text' field returns a validation error
- Key exceeding 512 characters returns a validation error
- Text exceeding 100,000 characters returns a validation error
- Payment failure (insufficient USDC) results in a 402 response
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| key | string | HMAC secret. Required on HMAC SKUs. Omit it for plain digests and checksums. The key is not stored. |
| text | string | 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. |
Tags
x402
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