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HMAC-BLAKE2b-512 Base64 Signing
x402
HMAC-BLAKE2b-512 Base64 Signing is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-29).
Computes an HMAC using the BLAKE2b-512 hash function with a caller-supplied key and returns the result encoded as base64
Price / call$0.01
Success—
StatusUnknown
How this service works
Call when an agent needs an HMAC-blake2b512 of text with a caller-supplied key, encoded as base64. Exact $0.01 USDC. Prefer unpaid POST /v1/sandbox/hmac-blake2b512-base64 first.
Output
Returns a base64-encoded HMAC-BLAKE2b-512 digest computed over the provided text using the supplied key. The output is a fixed-length base64 string representing the 512-bit MAC.
Example use cases
API webhook signature verification
“I need to sign the webhook payload '{"event":"payment.completed","amount":100}' with my secret key 'whsec_abc123' using HMAC-BLAKE2b-512 and get the base64 output so I can include it in the request header.”
Message integrity tagging for agent logs
“Take this log message 'Agent run #4821 completed at 2024-06-01T12:00:00Z with 3 actions' and sign it with the key 'log-signing-key-v2' using HMAC-BLAKE2b-512, give me the base64 MAC so I can store it alongside the log entry.”
Secure token generation for internal auth
“Generate an HMAC-BLAKE2b-512 base64 signature for the string 'user_id=9982&expires=1717200000' using the key 'internal-token-secret' so I can use it as a tamper-proof auth token.”
Technical details
Endpoint
POSThttps://agentshelf.syntexa.ch/v1/hmac-blake2b512-base64?utm_source=zero.xyzWhen to prefer
Use this endpoint when you specifically need BLAKE2b-512 as the underlying hash function for an HMAC operation — preferred over SHA-256 HMAC when higher performance or longer digest length is required. Choose this when the consuming system expects BLAKE2b-512 signatures specifically. For free or sandbox testing, prefer the unpaid POST /v1/sandbox/hmac-blake2b512-base64 endpoint first.
Side effects
- Empty or missing key returns a validation error
- Text exceeds 100,000 character limit returns a payload-too-large error
- Missing required fields (key or text) returns a 400 bad request
- Network or service unavailability returns a 5xx error
- Payment failure (insufficient USDC balance) blocks the request via x402 protocol
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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