{"uid":"cap_hI63ehNOc8Z7HyWWnnPDx","slug":"hmac-sha512-base64-signing-f1e7872a","name":"HMAC-SHA512 Base64 Signing","description":"Call when an agent needs an HMAC-sha512 of text with a caller-supplied key, encoded as base64. Exact $0.002 USDC. Prefer unpaid POST /v1/sandbox/hmac-sha512-base64 first.","url":"https://agentshelf.syntexa.ch/v1/hmac-sha512-base64?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":"0.002","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":"$0.002/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_S4SPIY4U8-iRwqCOLVVa8","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.002","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Computes an HMAC-SHA512 signature of a given text using a caller-supplied key and returns the result encoded as base64.","exampleAgentPrompt":"Compute an HMAC-SHA512 signature for the text 'order_id=42&amount=99.99&currency=USD' using the secret key 'my-super-secret-key-2024' and give me the result as base64.","exampleUseCases":[{"title":"Signing webhook payloads for verification","prompt":"I need to sign this webhook payload 'user_id=1001&event=purchase&timestamp=1720000000' with the secret 'wh_secret_abc123' using HMAC-SHA512 and get the base64 result so I can include it as a signature header."},{"title":"Authenticating API request bodies","prompt":"Generate an HMAC-SHA512 base64 signature for the request body '{\"action\":\"transfer\",\"amount\":500}' using the key 'api-signing-key-xyz' so I can attach it to my outgoing API call."},{"title":"Integrity check for stored data","prompt":"Take this JSON string '{\"record_id\":\"R-9988\",\"value\":\"critical-data\"}' and produce an HMAC-SHA512 base64 MAC using the key 'storage-integrity-key' so I can store it alongside the record for tamper detection."}],"resultDescription":"Returns a base64-encoded string representing the HMAC-SHA512 digest of the input text computed with the provided key. No network calls or external dependencies are involved in the computation.","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 failure or insufficient USDC balance results in a 402 response"],"whenToPreferThis":"Choose this endpoint when you need a deterministic, server-side HMAC-SHA512 computation with base64 output and do not want to run crypto libraries locally. Prefer the free sandbox endpoint (POST /v1/sandbox/hmac-sha512-base64) for testing. Use this paid endpoint for production signing where a trusted remote computation is required.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-01T06:48:01.256Z","isFirstParty":false,"canonicalSlug":"hmac-sha512-base64-signing-f1e7872a"}