{"uid":"cap_khs8GVpRkMqt2oWJBR5Sb","slug":"hmac-sha3-512-base64url-signing-2c102223","name":"HMAC-SHA3-512 Base64url Signing","description":"Call when an agent needs an HMAC-sha3-512 of text with a caller-supplied key, encoded as base64url. Exact $0.008 USDC. Prefer unpaid POST /v1/sandbox/hmac-sha3-512-base64url first.","url":"https://agentshelf.syntexa.ch/v1/hmac-sha3-512-base64url?utm_source=zero.xyz","method":"POST","headers":{},"bodySchema":{"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."}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.008","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.008/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.008","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.008","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_ooEjB0dfQ7-NXkkcpZZmr","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.008","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Computes an HMAC-SHA3-512 digest of a given text using a caller-supplied key and returns the result encoded as base64url.","exampleAgentPrompt":"Can you compute an HMAC-SHA3-512 of the text 'order:12345:confirmed' using the key 'my-secret-key-abc' and give me the result as base64url?","exampleUseCases":[{"title":"Webhook payload integrity signing","prompt":"I need to sign the webhook body '{\"event\":\"payment.completed\",\"amount\":42}' with the HMAC-SHA3-512 algorithm using my secret key 'wh-secret-xK9p' and get back the base64url signature so I can attach it to the X-Signature header."},{"title":"API request authentication token","prompt":"Generate an HMAC-SHA3-512 base64url MAC for the string 'GET /api/orders/99?ts=1720000000' using the key 'api-signing-key-prod' so I can include it as the auth token in my request."},{"title":"Data tamper-detection checksum","prompt":"I want to create a tamper-detection MAC for this blob of config data: 'db_host=prod.db.internal;port=5432;ssl=true' — use the key 'config-integrity-key-2024' and give me the SHA3-512 HMAC as base64url."}],"resultDescription":"Returns a base64url-encoded string representing the HMAC-SHA3-512 digest of the input text computed with the provided key. The output is URL-safe and padding-free, ready to embed in headers, query strings, or JSON payloads.","failureModes":["Missing or empty 'key' field returns a validation error","Missing or empty 'text' field returns a validation error","Text exceeding 100,000 characters is rejected","Key exceeding 512 characters is rejected","Payment of $0.008 USDC not provided results in HTTP 402 Payment Required"],"whenToPreferThis":"Choose this endpoint when you specifically need SHA3-512 as the hash function for HMAC (rather than SHA2-256 or SHA2-512), and want the output pre-encoded as base64url without additional transformation. Prefer the free sandbox variant POST /v1/sandbox/hmac-sha3-512-base64url for testing before using this paid endpoint.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-02T06:49:58.050Z","isFirstParty":false,"canonicalSlug":"hmac-sha3-512-base64url-signing-2c102223"}