{"uid":"cap_8gHWTnUcjMYimtmaDmY9x","slug":"hmac-blake2s256-base64-hash-ccb37eab","name":"HMAC-BLAKE2s256 Base64 Hash","description":"Call when an agent needs an HMAC-blake2s256 of text with a caller-supplied key, encoded as base64. Exact $0.008 USDC. Prefer unpaid POST /v1/sandbox/hmac-blake2s256-base64 first.","url":"https://agentshelf.syntexa.ch/v1/hmac-blake2s256-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":"0.008","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":"$0.008/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.008","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.008","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_3p5-mbUUn5JrMNhOReX4a","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.008","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Computes an HMAC using the BLAKE2s-256 algorithm over caller-supplied text with a caller-supplied key, returning the result encoded as base64.","exampleAgentPrompt":"Compute an HMAC-BLAKE2s256 hash of the text 'order:12345:confirmed' using the secret key 'my-secret-key-abc' and give me the result as base64.","exampleUseCases":[{"title":"Webhook signature generation","prompt":"I need to sign this webhook payload 'user_id=42&event=signup' with my secret key 'wh-secret-x9z' using HMAC-BLAKE2s256, and give me the base64 signature to attach to the request."},{"title":"API request integrity tagging","prompt":"Can you produce a base64 HMAC-BLAKE2s256 authentication tag for the string 'GET /api/orders/99 ts=1720000000' using the key 'api-signing-key-2024'?"},{"title":"Message authenticity verification prep","prompt":"I want to verify that a message hasn't been tampered with — generate the HMAC-BLAKE2s256 base64 hash for the text 'transfer:500:USD:alice:bob' using key 'shared-secret-key-77' so I can compare it against what the server sent."}],"resultDescription":"A base64-encoded string representing the HMAC-BLAKE2s256 digest of the input text, computed using the provided key. The result is a fixed-length cryptographic authentication tag suitable for integrity verification or message signing.","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 (402) if $0.008 USDC is not provided"],"whenToPreferThis":"Choose this endpoint when you specifically need HMAC-BLAKE2s256 (not SHA-256 or SHA-512 HMAC) with base64 output — for example when interoperating with systems that use BLAKE2s for its speed and modern security properties. Use the sandbox endpoint (POST /v1/sandbox/hmac-blake2s256-base64) first to test without incurring costs.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-02T06:50:19.245Z","isFirstParty":false,"canonicalSlug":"hmac-blake2s256-base64-hash-ccb37eab"}