schema.json

{ "title": "Cardano Off-Chain Metadata"
, "$schema": "https://json-schema.org/draft-07/schema"
, "required":
  [ "subject"
  ]
, "additionalProperties": { "$ref": "#/definitions/entry" }
, "properties":
  { "subject":
    { "type": "string"
    , "description": "The subject, a namespace for multiple metadata entries, typically a hash digest."
    , "minLength": 1
    , "maxLength": 255
    }
  , "policy":
    { "type": "string"
    , "description": "A CBOR-serialized phase-1 monetary policy, used as a pre-image to produce a policyId."
    , "encoding": "base16"
    , "minLength": 56
    , "maxLength": 120
    }
  , "preimage":
    { "type": "object"
    , "description": "A hashing algorithm identifier and a base16-enocoded bytestring, such that the bytestring is the preimage of the metadata subject under that hash function."
    , "requiredProperties": [ "alg", "msg" ]
    , "properties":
      { "alg":
          { "type": "string"
          , "description": "A hashing algorithm identifier. The length of the digest is given by the subject."
          , "enum":
            [ "sha1", "sha", "sha3", "blake2b", "blake2s", "keccak", "md5" ]
          }
      , "msg":
        { "type": "string"
        , "description": "The actual preimage."
        , "encoding": "base16"
        }
      }
    }
  , "name":
    { "type": "string"
    , "description": "A human-readable name for the metadata subject, suitable for use in an interface or in running text."
    , "maxLength": 50
    , "minLength": 1
    }
  , "description":
    { "type": "string"
    , "description": "A longer description of the metadata subject, suitable for use when inspecting the metadata subject itself."
    , "maxLength": 500
    }
  , "ticker":
    { "type": "string"
    , "description": "A short identifier for the metadata subject, suitable to show in listings or tiles."
    , "maxLength": 9
    , "minLength": 2
    }
  , "decimals":
    { "type": "integer"
    , "description": "When the metadata subject refers to a monetary policy, refers to the number of decimals of the currency."
    , "minimum": 1
    , "maximum": 19
    }
  , "url":
    { "type": "string"
    , "description": "A universal resource identifier pointing to additional information about the metadata subject."
    , "format": "uri"
    , "maxLength": 250
    }
  , "logo":
    { "type": "string"
    , "description": "A `image/png` object which is 64KB in size at most."
    , "encoding": "base64"
    , "maxLength": 87400
    }
  }
, "definitions":
  { "entry":
    { "type": "object"
    , "additionalProperties": false
    , "required":
      [ "value"
      , "sequenceNumber"
      , "signatures"
      ]
    , "properties":
      { "value": {}
      , "sequenceNumber": { "$ref": "#/definitions/sequenceNumber" }
      , "signatures": { "$ref": "#/definitions/signatures" }
      }
    }
  , "sequenceNumber":
    { "type": "integer"
    , "minimum": 0
    }
  , "signatures":
    { "type": "array"
    , "items":
      { "type": "object"
      , "additionalProperties": false
      , "required":
        [ "publicKey"
        , "signature"
        ]
      , "properties":
        { "publicKey":
          { "type": "string"
          , "description": "An Ed25519 Public key, verifying the companion signature."
          , "encoding": "base16"
          , "minLength": 64
          , "maxLength": 64
          }
        , "signature":
          { "type": "string"
          , "description": "A signed attestation."
          , "encoding": "base16"
          , "minLength": 128
          , "maxLength": 128
          }
        }
    }
    }
  }
}