json_schema: {
      "$schema": "http://json-schema.org/draft-04/schema#",
      "id": "https://github.com/ml-learning/digital-certificates-schema/issuer-schema-v2.json",
      "type": "object",
      "properties": {
          "issuer_key": {
              "type": "array",
              "items": {
                  "type": "object",
                  "properties": {
                      "date": {
                          "type": "string",
                          "format": "date-time",
                          "description": "Date time ISO-8601 format of the date that the keys were issued."
                      },
                      "key": {
                          "type": "string",
                          "description": "Bitcoin address (compressed public key, usually 24 characters) that the issuer uses to issue the certificates."
                      }
                  },
                  "additionalProperties": false,
                  "required": [
                      "date",
                      "key"
                  ]
              }
          },
          "revocation_key": {
              "type": "array",
              "items": {
                  "type": "object",
                  "properties": {
                      "date": {
                          "type": "string",
                          "format": "date-time",
                          "description": "Date time ISO-8601 format of the date that the keys were issued."
                      },
                      "key": {
                          "type": "string",
                          "description": "Bitcoin address (compressed public key, usually 24 characters) that the issuer uses to revoke the certificates."
                      }
                  },
                  "additionalProperties": false,
                  "required": [
                      "date",
                      "key"
                  ]
              }
          }
      },
      "additionalProperties": false,
      "required": [
          "issuer_key",
          "revocation_key"
      ]
  }