{"uid":"cap_qBkNymeTddxF1elj__91R","slug":"hmac-sha224-base64url-signer-58433c72","name":"HMAC-SHA224 Base64URL Signer","description":"Call when an agent needs an HMAC-sha224 of text with a caller-supplied key, encoded as base64url. Exact $0.002 USDC. Prefer unpaid POST /v1/sandbox/hmac-sha224-base64url first.","url":"https://agentshelf.syntexa.ch/v1/hmac-sha224-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":"0.002","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_4C_fvsWKy4bje7E77o5tS","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-SHA224 digest of input text using a caller-supplied key and returns it encoded as base64url.","exampleAgentPrompt":"Can you compute the HMAC-SHA224 of the text 'hello world' using the key 'mysecretkey' and give me the result as a base64url string?","exampleUseCases":[{"title":"Webhook signature verification","prompt":"I need to sign the webhook payload 'user.created:{\"id\":42}' with the key 'wh_secret_abc123' using HMAC-SHA224 and base64url-encode the result so I can attach it as a header."},{"title":"API request authentication token","prompt":"Generate a base64url HMAC-SHA224 signature for the string 'GET /orders/99?ts=1720000000' using my signing key 'k9Xz2mP7qR' so I can authenticate this API call."},{"title":"Data integrity checksum for stored record","prompt":"Compute an HMAC-SHA224 of 'invoice:INV-2024-0055,amount:299.00,due:2024-09-01' with key 'inv_integrity_key' encoded as base64url so I can store it alongside the record to detect tampering."}],"resultDescription":"Returns a base64url-encoded HMAC-SHA224 digest string computed from the provided text and key. The digest is a fixed-length cryptographic authentication code that can be used for integrity verification or message authentication.","failureModes":["Empty or missing key returns validation error","Text exceeding 100,000 characters is rejected","Empty text returns validation error","Key exceeding 512 characters is rejected","Malformed request body returns 400 error","Payment failure or insufficient USDC balance blocks the call"],"whenToPreferThis":"Choose this endpoint when you specifically need HMAC-SHA224 (not SHA256 or SHA512) output encoded as base64url rather than hex. It is ideal for agents that need a simple, stateless, paid cryptographic signing primitive without managing local crypto libraries. Use the free sandbox endpoint (/v1/sandbox/hmac-sha224-base64url) for testing before incurring the $0.002 USDC per-call charge.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-02T06:50:04.205Z","isFirstParty":false,"canonicalSlug":"hmac-sha224-base64url-signer-58433c72"}