{"uid":"cap_jEKmeA8VaRtfMNaIvPyAB","slug":"hmac-sha384-base64url-signer-68d3e65d","name":"HMAC-SHA384 Base64url Signer","description":"Call when an agent needs an HMAC-sha384 of text with a caller-supplied key, encoded as base64url. Exact $0.01 USDC. Prefer unpaid POST /v1/sandbox/hmac-sha384-base64url first.","url":"https://agentshelf.syntexa.ch/v1/hmac-sha384-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":"0.01","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":"$0.01/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.01","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.01","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_v_uT_6O0AOjwfgpAnw8Sr","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.01","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Computes an HMAC-SHA384 digest of text using a caller-supplied key and returns it encoded as base64url","exampleAgentPrompt":"Compute an HMAC-SHA384 signature of the text 'order:12345:confirmed' using the secret key 'mySecretKey2024' and give me the result as base64url.","exampleUseCases":[{"title":"Signing webhook payloads securely","prompt":"I need to sign this webhook body — the text is '{\"event\":\"payment.completed\",\"id\":\"evt_99\"}' — using my secret key 'wh_secret_abc123' with HMAC-SHA384, encoded as base64url so I can include it in the header."},{"title":"Generating API request signatures","prompt":"My upstream API requires an HMAC-SHA384 base64url signature of the request body 'GET /resource?user=42' using the key 'api-signing-key-xyz'. Can you generate that signature for me?"},{"title":"Creating integrity tokens for data pipelines","prompt":"I want to produce an HMAC-SHA384 base64url digest of the string 'pipeline-run:2024-06-01:dataset-A' with the key 'pipeline-secret-88' so I can attach it as a tamper-proof integrity token."}],"resultDescription":"A base64url-encoded string representing the HMAC-SHA384 digest of the provided text, computed with the supplied key. The response contains the signature ready to be embedded in headers, tokens, or integrity checks.","failureModes":["Empty or missing 'key' field returns a validation error","Empty or missing 'text' field returns a validation error","Text exceeding 100,000 characters is rejected","Key exceeding 512 characters is rejected","Payment failure results in a 402 response; use the sandbox endpoint first to verify behavior","Malformed JSON body returns a 400 error"],"whenToPreferThis":"Choose this endpoint when you need an HMAC-SHA384 digest specifically encoded as base64url (URL-safe, no padding issues), rather than hex or standard base64. Prefer this over HMAC-SHA512 variants when the receiving system expects SHA384. Use the free sandbox endpoint (/v1/sandbox/hmac-sha384-base64url) during development to avoid costs; switch to this paid endpoint in production workflows requiring guaranteed compute.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-02T06:46:37.128Z","isFirstParty":false,"canonicalSlug":"hmac-sha384-base64url-signer-68d3e65d"}