{"uid":"cap_nWW_tEUnqQc4Mok3XZ2fR","slug":"agentshelf-syntexa-ch-hmac-blake2s256-hex-f14c45ca","name":"agentshelf.syntexa.ch HMAC-BLAKE2s256 Hex","description":"Call when an agent needs an HMAC-blake2s256 of text with a caller-supplied key, encoded as hex. Exact $0.007 USDC. Prefer unpaid POST /v1/sandbox/hmac-blake2s256-hex first.","url":"https://agentshelf.syntexa.ch/v1/hmac-blake2s256-hex?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":"0.007","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":"$0.007/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.007","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.007","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_pxIr0TKp7_c6eDtAVy9Et","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.007","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 hash function with a caller-supplied key over input text, returning the result as a lowercase hex string.","exampleAgentPrompt":"Can you compute the HMAC-BLAKE2s256 hex digest of the text 'hello world' using the secret key 'mysecretkey123'?","exampleUseCases":[{"title":"API request signing for webhooks","prompt":"I need to sign this webhook payload 'user_id=42&event=purchase' with my secret key 'wh_secret_abc789' using HMAC-BLAKE2s256 — give me the hex digest so I can attach it as a signature header."},{"title":"Message integrity verification token","prompt":"Generate an HMAC-BLAKE2s256 hex tag for the message 'transfer:1000:USD:account_9871' using the key 'integrity_key_xz12' so I can verify it hasn't been tampered with later."},{"title":"Keyed checksum for data pipeline","prompt":"I have a data record 'sensor_id=55;reading=98.6;timestamp=1720000000' that I want to integrity-stamp using HMAC-BLAKE2s256 with the key 'pipeline_secret_007' — what's the hex output?"}],"resultDescription":"Returns a hex-encoded HMAC-BLAKE2s256 digest string computed over the provided text using the supplied key. The output is a fixed-length lowercase hexadecimal string representing the 256-bit MAC.","failureModes":["Missing or empty 'key' field returns a validation error","Missing or empty 'text' field returns a validation error","Text exceeding 100,000 characters returns a length error","Key exceeding 512 characters returns a validation error","Payment of $0.007 USDC not provided or rejected triggers HTTP 402","Network timeout if the service is temporarily unavailable"],"whenToPreferThis":"Choose this endpoint when you need a BLAKE2s-256 based HMAC specifically — as opposed to SHA-256 or SHA-512 HMAC — because BLAKE2s is faster on constrained hardware and provides comparable security. Use it when your protocol or counterparty requires BLAKE2s keyed authentication. If cost is a concern, try the free sandbox endpoint POST /v1/sandbox/hmac-blake2s256-hex first.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-02T06:50:17.417Z","isFirstParty":false,"canonicalSlug":"agentshelf-syntexa-ch-hmac-blake2s256-hex-f14c45ca"}