{"uid":"cap_EdOPVKB80lr8VQRGAGzs1","slug":"hmac-sha3-384-base64url-signer-d9823064","name":"HMAC-SHA3-384 Base64URL Signer","description":"Call when an agent needs an HMAC-sha3-384 of text with a caller-supplied key, encoded as base64url. Exact $0.005 USDC. Prefer unpaid POST /v1/sandbox/hmac-sha3-384-base64url first.","url":"https://agentshelf.syntexa.ch/v1/hmac-sha3-384-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":"0.005","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":"$0.005/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_VG6r5PLIbdxQxNW4z0tZ7","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.005","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Computes an HMAC-SHA3-384 message authentication code of input text using a caller-supplied key, returning the result encoded as base64url.","exampleAgentPrompt":"Compute the HMAC-SHA3-384 of the text 'Hello, world!' using the key 'my-secret-key-abc123' and give me the result as base64url.","exampleUseCases":[{"title":"Signing webhook payload for delivery","prompt":"I need to sign this webhook payload 'order_id=42&status=shipped' with the secret key 'wh-secret-xyz' using HMAC-SHA3-384, and I want the signature as base64url so I can attach it to the request header."},{"title":"Authenticating API request body","prompt":"Can you produce an HMAC-SHA3-384 base64url MAC for the JSON string '{\"user\":\"alice\",\"action\":\"transfer\"}' using the key 'api-key-9f8e7d' so I can include it as a request signature?"},{"title":"Verifying data integrity token","prompt":"Generate an HMAC-SHA3-384 base64url digest for the message 'invoice:2024-001:$500.00' with the key 'invoice-signing-key-v2' — I need it to attach to the invoice as a tamper-evident token."}],"resultDescription":"Returns a base64url-encoded HMAC-SHA3-384 digest computed over the provided text using the supplied key. The output is a compact, URL-safe string suitable for use as a signature or MAC in headers, query parameters, or storage.","failureModes":["Missing or empty 'key' field returns a validation error","Missing or empty 'text' field returns a validation error","Key or text exceeding maximum length (512 and 100000 chars respectively) returns a 400 error","Payment failure or insufficient USDC balance prevents the call from completing","Malformed JSON request body results in a parse error"],"whenToPreferThis":"Choose this endpoint when you specifically need HMAC-SHA3-384 (not SHA-256 or SHA-512) with base64url output encoding — for example, when interoperating with a system that requires SHA3-family MACs or URL-safe base64 encoding. Prefer the free sandbox variant (/v1/sandbox/hmac-sha3-384-base64url) for testing; use this paid endpoint in production or when the sandbox is unavailable.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-02T06:50:18.031Z","isFirstParty":false,"canonicalSlug":"hmac-sha3-384-base64url-signer-d9823064"}