Verifiable random function — deterministic, publicly verifiable randomness bound to your seed and signed by the 2s key. proof = deterministic EIP-191 signature over the seed (same seed always yields the same proof, so the outcome cannot be re-rolled or cherry-picked); random = keccak256(proof), a uniform 32-byte value. Returns the seed, signed message, proof, signer address, random (hex + uint + float in [0,1)). Verify offline: recover the signer from (message, proof) and confirm keccak256(proof) == random. For provably-fair draws, lotteries, sortition, and tie-breaks between agents.
/api/crypto/vrfPAYMENT-SIGNATURE.The vrf API is a pay-per-call crypto endpoint built for AI agents and autonomous software. Verifiable random function — deterministic, publicly verifiable randomness bound to your seed and signed by the 2s key.
There is no signup and no API key. An agent (or any HTTP client) hits the endpoint, receives an x402 "402 Payment Required" challenge, signs a sub-cent USDC payment on Base or Solana, and retries — the data comes back on the paid request. That makes it a drop-in vrf data source for an agent tool-use loop, an MCP host, or a backend that needs crypto data on demand without onboarding to yet another vendor portal.
| Name | Type | Description |
|---|---|---|
seedrequired | string | Any seed string — a request id, block hash, commitment, etc. min 1 chars · max 256 chars |
# 1. Probe with no auth → 402 envelope with PaymentRequirements curl -sS 'https://2s.io/api/crypto/vrf?seed=example' # 2. Sign + retry with PAYMENT-SIGNATURE: curl -sS 'https://2s.io/api/crypto/vrf?seed=example' \ -H 'PAYMENT-SIGNATURE: <base64-json-payload>' # Or use the canonical runner (handles probe → sign → retry): # EVM_PRIVATE_KEY=0x... node --env-file=.env.local \ # --experimental-strip-types scripts/x402-pay.ts \ # 'https://2s.io/api/crypto/vrf?seed=example'
import { TwoS } from '@2sio/sdk'
const client = new TwoS({
privateKey: process.env.EVM_PRIVATE_KEY as `0x${string}`,
})
const result = await client.crypto.vrf({
"seed": "example"
})
console.log('endpoint:', result.endpoint)
console.log('cost:', result.costUsd, 'USDC')
console.log('tx:', result.settlement?.txHash)
console.log('data:', result.data)import os
from twosio import TwoS
client = TwoS(private_key=os.environ["EVM_PRIVATE_KEY"])
result = client.crypto.vrf(seed="example")
print("endpoint:", result.endpoint)
print("cost:", result.cost_usd, "USDC")
print("tx:", (result.settlement or {}).get("tx_hash"))
print("data:", result.data)// 1. Add @2sio/mcp to your MCP host config (Claude Desktop example below).
// EVM_PRIVATE_KEY funds x402 payments per call.
// claude_desktop_config.json
{
"mcpServers": {
"2sio": {
"command": "npx",
"args": ["-y", "@2sio/mcp"],
"env": { "EVM_PRIVATE_KEY": "0x..." }
}
}
}
// 2. Once the server is running, agents call this tool via standard MCP:
{
"jsonrpc": "2.0",
"id": 1,
"method": "tools/call",
"params": {
"name": "crypto.vrf",
"arguments": {
"seed": "example"
}
}
}| Field | Type | Description |
|---|---|---|
ok | boolean | one of: true |
items | array | |
total | integer | Total matching rows upstream; null when unknown. |
source | object |
{
"ok": true,
"items": [
{
"seed": "example",
"signer": "example",
"alg": "example",
"version": "example",
"message": "example",
"proof": "example",
"random": "example",
"randomUint": "example",
"randomFloat": 1
}
],
"total": 1,
"source": {
"provider": "example",
"url": "example",
"license": "example"
}
}