{"uid":"cap_Dc28JIx7DW3Td65eQDbnr","slug":"hmac-sha224-base64-signing-b00296d8","name":"HMAC-SHA224 Base64 Signing","description":"Call when an agent needs an HMAC-sha224 of text with a caller-supplied key, encoded as base64. Exact $0.001 USDC. Prefer unpaid POST /v1/sandbox/hmac-sha224-base64 first.","url":"https://agentshelf.syntexa.ch/v1/hmac-sha224-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":"0.001","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":"$0.001/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.001","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.001","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_Ev0-2j30pBZ-Fjv7fbahQ","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.001","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 message authentication code over a given text using a caller-supplied key and returns the result encoded as base64.","exampleAgentPrompt":"Compute an HMAC-SHA224 of the text 'hello world' using the secret key 'mysecretkey' and give me the result as base64.","exampleUseCases":[{"title":"Webhook signature verification","prompt":"I need to sign the webhook payload '{\"event\":\"order.completed\",\"id\":\"abc123\"}' using HMAC-SHA224 with the key 'wh_secret_xyz' and get the base64 result so I can include it in my signature header."},{"title":"API request authentication","prompt":"Generate an HMAC-SHA224 base64 signature for the string 'GET/v2/users1700000000' using the key 'api_secret_456' — I need to attach it as an auth token to my outgoing API request."},{"title":"Data integrity tagging","prompt":"Compute the HMAC-SHA224 of the text 'invoice-2024-09-01:$4200.00:client-789' with key 'ledger_key_001' and return it as base64 so I can store it alongside the record as a tamper-evident tag."}],"resultDescription":"A JSON response containing the base64-encoded HMAC-SHA224 digest of the input text, computed using the provided secret key. The output is a deterministic, fixed-length string suitable for use in authentication headers, integrity checks, or storage alongside records.","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 (insufficient USDC balance) results in a 402 response","Network timeout if the service is temporarily unavailable"],"whenToPreferThis":"Prefer this endpoint when you specifically need HMAC-SHA224 (not SHA256 or SHA512) with base64 output encoding and a caller-supplied key. It is a pure computational endpoint with no side effects, making it safe to call repeatedly. Use the free sandbox endpoint POST /v1/sandbox/hmac-sha224-base64 for testing before incurring the $0.001 USDC charge on this paid endpoint.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-01T06:47:56.466Z","isFirstParty":false,"canonicalSlug":"hmac-sha224-base64-signing-b00296d8"}