Verifiable Random pick — string selection with or without replacement bound to a

Verifiable Random pick — string selection with or without replacement bound to a future drand round the server waits for (typically 3-6s) and verifies locally, with a reproducible proof transcript.

Paid test badge: not yet. The checks above are free: we call the tool without paying and read the payment request it sends back. The Verified badge needs paid calls whose answers match the promised output, and nobody can buy a badge.

Endpoint

POST https://verifiable-random.use.x402atlas.com/pick

Our checks, last 30 days

Example input (from the provider)

{
  "body": {
    "algorithm_version": "drand-hkdf-sha256-v1",
    "client_seed": "example",
    "count": 2,
    "items": [
      "red",
      "green",
      "blue"
    ],
    "replacement": false,
    "target_round": 0
  },
  "bodyType": "json",
  "method": "POST",
  "type": "http"
}

Promised output schema (from the provider)

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "properties": {
    "input": {
      "additionalProperties": false,
      "properties": {
        "body": {
          "additionalProperties": false,
          "description": "String selection request bound to a future drand round.",
          "properties": {
            "algorithm_version": {
              "default": "drand-hkdf-sha256-v1",
              "description": "Optional version guard; when supplied it must match the server's pinned derivation algorithm.",
              "enum": [
                "drand-hkdf-sha256-v1"
              ],
              "type": "string"
            },
            "client_seed": {
              "default": "",
              "description": "Optional public domain-separation label, not secret entropy.",
              "maxLength": 256,
              "type": "string"
            },
            "count": {
              "description": "Number of values to select.",
              "maximum": 1000,
              "minimum": 1,
              "type": "integer"
            },
            "items": {
              "description": "Candidate strings to select from, at most 131072 UTF-8 bytes combined; duplicate values are allowed and remain distinguishable by original_indices.",
              "items": {
                "maxLength": 256,
                "type": "string"
              },
              "maxItems": 1000,
              "minItems": 1,
              "type": "array"
            },
            "replacement": {
              "default": false,
              "description": "False selects each input position at most once; true makes independent draws and permits repeated positions.",
              "type": "boolean"
            },
            "target_round": {
              "default": 0,
              "description": "0 asks the server to choose the next safe unpublished round; a positive value makes a client_fixed commitment and must still be safely in the future.",
              "minimum": 0,
              "type": "integer"
            }
          },
          "required": [
            "items",
            "count"
          ],
          "type": "object"
        },
        "bodyType": {
          "enum": [
            "json",
            "form-data",
            "text"
          ],
          "type": "string"
        },
        "method": {
          "enum": [
            "POST"
          ],
          "type": "string"
        },
        "type": {
          "const": "http",
          "type": "string"
        }
      },
      "required": [
        "type",
        "method",
        "bodyType",
        "body"
      ],
      "type": "object"
    },
    "output": {
      "properties": {
        "example": {
          "additionalProperties": false,
          "description": "Verifiable Random result and complete drand derivation transcript.",
          "properties": {
            "algorithm_version": {
              "description": "Pinned canonicalization, derivation, and sampling algorithm version required to reproduce the result.",
              "enum": [
                "drand-hkdf-sha256-v1"
              ],
              "type": "string"
            },
            "beacon": {
              "additionalProperties": false,
              "description": "Locally verified drand Quicknet proof used as the public randomness source.",
              "properties": {
                "chain_hash": {
                  "description": "Pinned Quicknet chain hash used to fetch and verify the round.",
                  "enum": [
                    "52db9ba70e0cc0f6eaf7803dd07447a1f5477735fd3f661792ba94600c84e971"
                  ],
                  "type": "string"
                },
                "network": {
                  "description": "Pinned drand network name.",
                  "enum": [
                    "quicknet"
                  ],
                  "type": "string"
                },
                "randomness": {
                  "description": "Lowercase hexadecimal randomness derived from the verified signature.",
                  "pattern": "^[0-9a-f]{64}$",
                  "type": "string"
                },
                "round": {
                  "description": "Exact verified Quicknet round used for this result.",
                  "minimum": 1,
                  "type": "integer"
                },
                "scheduled_time": {
                  "description": "Scheduled UTC publication time of the selected round.",
                  "format": "date-time",
                  "type": "string"
                },
                "scheme": {
                  "description": "Pinned drand signature scheme.",
                  "enum": [
                    "bls-unchained-g1-rfc9380"
                  ],
                  "type": "string"
                },
                "signature": {
                  "description": "Lowercase hexadecimal BLS signature verified against the pinned Quicknet public key.",
                  "pattern": "^[0-9a-f]{96}$",
                  "type": "string"
                }
              },
              "required": [
                "network",
                "chain_hash",
                "scheme",
                "round",
                "scheduled_time",
                "randomness",
                "signature"
              ],
              "type": "object"
            },
            "example_only": {
              "description": "True only in compiled catalog/keepalive examples; live paid results are false.",
              "type": "boolean"
            },
            "operation": {
              "description": "Random operation performed by this route.",
              "enum": [
                "pick"
              ],
              "type": "string"
            },
            "processed_at": {
              "description": "UTC time when the service accepted the request and committed to the round-selection decision.",
              "format": "date-time

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