{"uid":"cap_ld-z2cgGqwSEG5LpsvzfB","slug":"hmac-blake2s256-base64url-computation-ffdcb484","name":"HMAC-BLAKE2s256 Base64url Computation","description":"Call when an agent needs an HMAC-blake2s256 of text with a caller-supplied key, encoded as base64url. Exact $0.009 USDC. Prefer unpaid POST /v1/sandbox/hmac-blake2s256-base64url first.","url":"https://agentshelf.syntexa.ch/v1/hmac-blake2s256-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":"0.009","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":"$0.009/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.009","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.009","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_gx-JFeZzHACm842H0JUUZ","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.009","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 BLAKE2s256 algorithm on a given text with a caller-supplied key and returns the result encoded as base64url.","exampleAgentPrompt":"Compute an HMAC-BLAKE2s256 of the text 'Hello, world!' using the key 'mysecretkey' and give me the result as a base64url string.","exampleUseCases":[{"title":"API request signature generation","prompt":"I need to sign the payload 'user_id=42&action=purchase' with the secret key 'sk_prod_abc123' using HMAC-BLAKE2s256 — give me the base64url output so I can attach it as a request signature."},{"title":"Message integrity verification token","prompt":"Generate an HMAC-BLAKE2s256 tag for the message 'invoice:9981:amount:250.00' using the key 'billing_secret_xyz' encoded as base64url so I can include it as an integrity token on the invoice."},{"title":"Webhook payload authentication","prompt":"I'm sending a webhook payload 'event=order_shipped&order_id=7743' and need an HMAC-BLAKE2s256 of that text with key 'webhook_signing_key_prod' as base64url to authenticate the webhook delivery."}],"resultDescription":"Returns a base64url-encoded HMAC-BLAKE2s256 digest string computed over the provided text using the supplied key. The response is a compact, URL-safe cryptographic MAC suitable for embedding in URLs, headers, or tokens.","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 of $0.009 USDC not provided results in HTTP 402","Network or server error returns 5xx response"],"whenToPreferThis":"Choose this endpoint when you specifically need HMAC-BLAKE2s256 (not SHA-256 or MD5) with a caller-controlled secret key and require base64url encoding for URL-safe output. Prefer the sandbox unpaid endpoint (/v1/sandbox/hmac-blake2s256-base64url) for testing. Use over sibling endpoints when the consumer requires keyed authentication (HMAC) rather than a plain digest, and when base64url encoding is mandated by the downstream system.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-02T06:50:06.132Z","isFirstParty":false,"canonicalSlug":"hmac-blake2s256-base64url-computation-ffdcb484"}