{"uid":"cap_wRvCTPX3WLzuzobCdTDQA","slug":"aimarket-fair-random-ecvrf-e87abc4c","name":"AIMarket Fair Random (ECVRF)","description":"Verifiable random bytes for a draw, raffle or tie-break: an ECVRF output over your seed plus a proof anyone can check offline. The same seed always gives the same output, so publish the seed first.","url":"https://modelmarket.dev/x402/fair-random?utm_source=zero.xyz","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"seed":{"type":"string","description":"the seed or message the draw is bound to (up to 4096 bytes)"},"num_bytes":{"type":"integer","description":"output length, 1-64 (default 32)"}}},"responseSchema":{"type":"json","example":{"result":{},"status":"ok","receipt":{},"service":"fair-random","capability_id":"sortes.draw@v1"}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.006","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":"$0.006/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.006","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.006","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_2037DQlvI7cZGd_Mx-o57","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.006","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Generates verifiable random bytes using an Elliptic Curve Verifiable Random Function (ECVRF) over a caller-supplied seed, returning both the random output and a cryptographic proof anyone can verify offline.","exampleAgentPrompt":"Run a verifiable random draw for our raffle using the seed 'WorldCup2025FinalDraw' and give me 32 random bytes along with the ECVRF proof so participants can verify the result is fair.","exampleUseCases":[{"title":"Provably fair NFT mint lottery","prompt":"We're doing a whitelist lottery for our NFT drop — use the seed 'NFTDrop-Phase1-2025-07-01' to generate 32 verifiable random bytes with a proof so anyone can confirm the selection was unrigged."},{"title":"Tournament tie-break draw","prompt":"Two players are tied in our chess tournament and we need to pick who goes first — generate a verifiable random result from the seed 'ChessFinal-TieBreak-Alice-vs-Bob' with 8 bytes and include the proof so both players can verify it."},{"title":"On-chain raffle winner selection","prompt":"I need to pick a raffle winner from our list of 500 entries — generate 64 verifiable random bytes using the seed 'CharityRaffle-June2025-Entry500' and give me the ECVRF proof so we can publish it for public verification."}],"resultDescription":"Returns verifiable random bytes (1–64 bytes, default 32) derived deterministically from the input seed via ECVRF, along with a cryptographic proof. The proof allows any third party to independently verify offline that the output was faithfully computed from the committed seed without any manipulation.","failureModes":["Seed exceeds 4096 bytes — request rejected","num_bytes outside 1–64 range — validation error","Payment not attached or insufficient USDC — 402 Payment Required","Malformed request body — 400 Bad Request"],"whenToPreferThis":"Choose this endpoint when you need publicly auditable, tamper-proof randomness where participants must be able to verify the draw offline without trusting the operator — such as lotteries, raffles, NFT drops, or tie-breaks. The deterministic ECVRF property means committing the seed publicly before calling ensures no one (including the caller) can cherry-pick the outcome. Prefer this over a simple PRNG or opaque randomness source whenever fairness auditability is a requirement.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-12T06:38:13.965Z","isFirstParty":false,"canonicalSlug":"aimarket-fair-random-ecvrf-e87abc4c"}