Uniform integers in [min, max] derived from ONE verified randomness draw by rejection samp

[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "payTo": "0x5D17c40FD6b119dc6006C4Ab3C20a917FCaB2aCD",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "5808",
    "maxTimeoutSeconds": 60
  },
  {
    "scheme": "exact",
    "network": "animica:1",
    "payTo": "anim1zqpsmegc0qcvzjfukm89xs0zeu3eqyyyel7kelehuszvwfarqypky2gr946ga",
    "asset": "ANM",
    "amount": "68989547038",
    "maxTimeoutSeconds": 60
  }
]

{
  "animica": {
    "catalog": "https://animica.dev/.well-known/x402",
    "content_type": "application/json",
    "currency": "USDC",
    "description": "Uniform integers in [min, max] derived from ONE verified randomness draw by rejection sampling (never modulo bias) — up to 1000 per request. The response carries the raw draw, the node's source/health/attestation and the exact rule, so you can recompute every integer offline.",
    "documentation": "https://animica.dev/x402#product-random_int",
    "free_trial": {
      "endpoint": "POST /x402/random/int/trial",
      "limit_per_day": 3,
      "note": "Same code and same response shape as the paid endpoint. No payment, no payment headers. Quota is per client per UTC day; when it is spent this endpoint says so and points back here.",
      "price": "0",
      "url": "https://animica.dev/x402/random/int/trial"
    },
    "name": "Uniform random integers",
    "openapi": "https://animica.dev/x402/openapi.json",
    "price": "0.005808",
    "product": "random_int",
    "provider": "Animica",
    "terms": {
      "amount_atomic": "5808",
      "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
      "chain_id": 8453,
      "network": "eip155:8453",
      "pay_to": "0x5D17c40FD6b119dc6006C4Ab3C20a917FCaB2aCD",
      "scheme": "exact"
    },
    "x402_version": 2
  },
  "bazaar": {
    "discoverable": true,
    "info": {
      "input": {
        "body": {
          "count": 3,
          "max": 6,
          "min": 1
        },
        "bodyType": "json",
        "method": "POST",
        "type": "http"
      },
      "output": {
        "example": {
          "attestation": {
            "alg": "ed25519",
            "attested": false,
            "backend": "software",
            "digest_hex": "14a2636cf09e18539ab6ed62de65af350c2f6014d269b74d127fc1604c7aa68a",
            "public_key_hex": "8a2228f4bde8f72964a7ff4aa759f24932ae1cccd9462ad94ca6e508d6b87a64",
            "signature_hex": "bee4d32ee31dd92b07f1eee3113ed722c3c96c5fae98c509bcca8f66a5ceaff3eb4a6cd41cd97fc32deebdeeab18b4affea467549dd4ef387ddbdae6d415e900"
          },
          "bytes": 32,
          "derivation": {
            "algorithm": "uniform-int-rejection-sampling",
            "domain": "animica/qrng/public/v1",
            "entropy_hex": "8e8d85d9c03247ffdff7b3db1c917b7a0e97a569e8cf098071dd91cc9121ae55",
            "kind": "range",
            "recompute": {
              "beacon_hex": "8e8d85d9c03247ffdff7b3db1c917b7a0e97a569e8cf098071dd91cc9121ae55",
              "kind": "range",
              "output": [
                5,
                1,
                2
              ],
              "params": {
                "count": 3,
                "hi": 6,
                "lo": 1
              },
              "request_id": "",
              "round_id": 0
            },
            "request_id": "",
            "rules": {
              "seed": "seed = sha3_256(\"animica/qrng/public/v1\" || \"|k:\" || kind || \"|r:\" || request_id || \"|b:\" || bytes(randomness))",
              "stream": "stream = sha3_256(seed || be8(counter)) for counter = 0,1,2,… concatenated; consumed left to right, never reused",
              "uniform_int": "randbelow(n): k = floor((bitlen(n)+7)/8)+1 bytes per attempt, read big-endian as x; limit = 2^(8k); accept when x < limit - (limit mod n); value = x mod n. Rejected attempts still consume their k bytes. n <= 1 consumes nothing and returns 0. This is rejection sampling — plain \"x mod n\" would bias small values."
            },
            "seed_hex": "5fb4cc0e8007c201060453ee9b7cacb38444d32d76d423c61e601117fadd3068",
            "steps": [
              "seed the DRNG with kind=\"range\" and your request_id over the raw randomness above",
              "for i = 0..2: ints[i] = 1 + randbelow(6)"
            ],
            "stream_bytes_consumed": 6,
            "verifier": {
              "api": "AnimicaBeacon.drngSeed(entropy, kind, request_id) + AnimicaBeacon.QDRNG reproduce the stream; AnimicaBeacon.verifyResult(derivation.recompute) === true whenever `recompute` is present",
              "file": "randomness/beacon_api/static/verify.js (Animica repo, github.com/animicaorg) — zero-dependency, runs in Node and the browser",
              "note": "verify.js calls the seed material `beacon` because it was written for beacon rounds. This product is NOT a beacon round: the seed material is the raw `randomness` bytes above, which the node signed (see `verification`)."
            }
          },
          "encoding": "hex",
          "health": {
            "min_entropy_per_byte": 7.8216,
            "passed": true
          },
          "product": "random_int",
          "randomness": "8e8d85d9c03247ffdff7b3db1c917b7a0e97a569e8cf098071dd91cc9121ae55",
          "result": {
            "count": 3,
            "ints": [
              5,
              1,
              2
            ],
            "max": 6,
            "min": 1
          },
          "source": {
            "attested": false,
            "device_path": null,
            "is_hardware": false,
            "is_quantum": false,
            "model": "os.urandom CSPRNG",
            "name": "software-fallback",
            "notes": "non-attested fallback for testing/degraded mode",
            "vendor": "os"
          },
          "verification": {
            "attested": false,
            "method": "signed-digest-attestation",
            "rules": [
              "attestation.digest_hex == sha3_256(bytes(randomness))",
              "ed25519_verify(pubkey=attestation.public_key_hex, message=raw_bytes(attestation.digest_hex), signature=attestation.signature_hex)"
            ],
            "trust_model": "signed by the serving node, not client-recomputable: you trust the node's entropy source, then verify it signed exactly these bytes. Check health.passed and attestation.attested before relying on it.",
            "verifier": "randomness/beacon_api/static/verify.js in the animica repo (github.com/animicaorg) — dependency-free Node module exporting sha3_256; pair with any ed25519 verifier"
          }
        },
        "type": "json"
      }
    },
    "schema": {
      "$schema": "https://json-schema.org/draft/2020-12/schema",
      "properties": {
        "input": {
          "properties": {
            "body": {
              "properties": {
                "count": {
                  "description": "how many integers, 1..1000 (default 1; alias n)",
                  "type": "integer"
                },
                "max": {
                  "description": "upper bound, inclusive (>= min)",
                  "type": "integer"
                },
                "min": {
                  "description": "lower bound, inclusive",
                  "type": "integer"
                },
                "request_id": {
                  "description": "your own tag; mixed into the DRNG seed so you can recompute this exact draw",
                  "type": "string"
                }
              },
              "required": [
                "min",
                "max"
              ],
              "type": "object"
            },
            "bodyType": {
              "enum": [
                "json"
              ],
              "type": "string"
            },
            "method": {
              "enum": [
                "POST"
              ],
              "type": "string"
            },
            "type": {
              "const": "http",
              "type": "string"
            }
          },
          "required": [
            "type",
            "method"
          ],
          "type": "object"
        },
        "output": {
          "properties": {
            "example": {},
            "type": {
              "type": "string"
            }
          },
          "required": [
            "type"
          ],
          "type": "object"
        }
      },
      "required": [
        "input"
      ],
      "type": "object"
    }
  },
  "discovery": {
    "discoverable": true,
    "info": {
      "entropy": {
        "attested": false,
        "health_passed": true,
        "is_hardware": false,
        "is_quantum": false,
        "min_entropy_per_byte": 7.7725,
        "model": "os.urandom CSPRNG",
        "note": "observed on the gateway's own readiness draw, published unpaid so the trust model is knowable before purchase; the same fields ride verbatim on every paid response",
        "observed_at": "2026-08-22T08:41:02.928Z",
        "signer_backend": "software",
        "source": "software-fallback",
        "vendor": "os"
      },
      "input": {
        "bodyFields": {
          "count": {
            "description": "how many integers, 1..1000 (default 1; alias n)",
            "required": false,
            "type": "integer"
          },
          "max": {
            "description": "upper bound, inclusive (>= min)",
            "required": true,
            "type": "integer"
          },
          "min": {
            "description": "lower bound, inclusive",
            "required": true,
            "type": "integer"
          },
          "request_id": {
            "description": "your own tag; mixed into the DRNG seed so you can recompute this exact draw",
            "required": false,
            "type": "string"
          }
        },
        "bodyType": "json",
        "method": "POST",
        "type": "http"
      },
      "output": {
        "description": "result {ints}, randomness (hex raw draw), source, health, attestation, verification, derivation {rules, steps, recompute} for offline recomputation, payment metadata",
        "type": "json"
      }
    }
  }
}

curl "https://animica.dev/x402/random/int"
# -> 402 Payment Required, accepts[] lists how to pay
# retry with a PAYMENT-SIGNATURE (or PAYMENT header) once paid

const res = await fetch("https://animica.dev/x402/random/int");
if (res.status === 402) {
  const { accepts } = await res.json();
  // pay one of accepts[] via an x402 client, then retry with the payment header
}

import httpx
res = httpx.get("https://animica.dev/x402/random/int")
if res.status_code == 402:
    accepts = res.json()["accepts"]
    # pay one of accepts[] via an x402 client, then retry with the payment header