{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://docs.qauth.dev/interaction/v1-rc.0/steps/captcha.json",
  "title": "urn:qauth:ia:captcha:v1-rc.0",
  "description": "A bot challenge, when a soft threshold requires one; the pending step resumes after it (ADR-017 Decisions 4 and 7). By default the built-in proof of work, whose script the ceremony app serves from the realm origin. An operator may name a hosted provider for the sign-up and sign-in pages only (ADR-019 Decision 5). A required challenge needs JavaScript and is never skipped.",
  "x-qauth-transports": [
    "interaction",
    "fipa"
  ],
  "type": "object",
  "properties": {
    "type": {
      "const": "urn:qauth:ia:captcha:v1-rc.0",
      "description": "The step name."
    },
    "params": {
      "$ref": "#/$defs/params"
    },
    "answer": {
      "$ref": "#/$defs/answer"
    },
    "personal": {
      "$ref": "#/$defs/personal"
    },
    "error": {
      "$ref": "#/$defs/error"
    },
    "amr": {
      "$ref": "#/$defs/amr"
    }
  },
  "required": [
    "type",
    "params",
    "answer",
    "personal",
    "amr"
  ],
  "examples": [
    {
      "type": "urn:qauth:ia:captcha:v1-rc.0",
      "params": {
        "provider": "pow",
        "challenge": "Qm9vbGVhbi1ub3QtYS1yZWFsLWNoYWxsZW5nZS0zMmI",
        "difficulty": 18
      },
      "answer": {
        "captcha_token": "AAAAAAAABl9x"
      },
      "personal": {},
      "amr": []
    }
  ],
  "$defs": {
    "params": {
      "description": "The challenge to solve: the built-in proof of work, or a hosted provider.",
      "oneOf": [
        {
          "type": "object",
          "properties": {
            "provider": {
              "const": "pow",
              "description": "The built-in proof of work."
            },
            "challenge": {
              "type": "string",
              "minLength": 22,
              "maxLength": 128,
              "pattern": "^[A-Za-z0-9_-]{22,128}$",
              "description": "The puzzle the engine issued."
            },
            "difficulty": {
              "type": "integer",
              "minimum": 1,
              "maximum": 32,
              "description": "How many leading zero bits the answer must produce."
            }
          },
          "required": [
            "provider",
            "challenge",
            "difficulty"
          ],
          "additionalProperties": false
        },
        {
          "type": "object",
          "properties": {
            "provider": {
              "const": "hosted",
              "description": "A hosted provider the operator named."
            },
            "name": {
              "type": "string",
              "minLength": 1,
              "maxLength": 32,
              "pattern": "^[a-z][a-z0-9_-]{0,31}$",
              "description": "The name the operator gave the hosted provider."
            },
            "site_key": {
              "type": "string",
              "minLength": 1,
              "maxLength": 256,
              "pattern": "^[A-Za-z0-9._-]+$",
              "description": "The provider’s public site key."
            }
          },
          "required": [
            "provider",
            "name",
            "site_key"
          ],
          "additionalProperties": false
        }
      ],
      "examples": [
        {
          "provider": "pow",
          "challenge": "Qm9vbGVhbi1ub3QtYS1yZWFsLWNoYWxsZW5nZS0zMmI",
          "difficulty": 18
        }
      ]
    },
    "answer": {
      "type": "object",
      "properties": {
        "captcha_token": {
          "type": "string",
          "minLength": 1,
          "maxLength": 4096,
          "pattern": "^[!-~]+$",
          "description": "The solution, or the provider’s token: printable ASCII, so 4096 characters are 4096 bytes."
        }
      },
      "required": [
        "captcha_token"
      ],
      "additionalProperties": false,
      "examples": [
        {
          "captcha_token": "AAAAAAAABl9x"
        }
      ]
    },
    "personal": {
      "type": "object",
      "properties": {},
      "additionalProperties": false,
      "examples": [
        {}
      ]
    },
    "error": {
      "type": "string",
      "enum": [
        "captcha_failed"
      ],
      "description": "Why the last answer was refused. A closed set."
    },
    "amr": {
      "type": "array",
      "items": {
        "type": "string"
      },
      "const": [],
      "description": "The RFC 8176 `amr` values a successful answer adds to the transaction: none, because the step proves no authenticator."
    }
  }
}