{
  "$schema": "http://json-schema.org/draft-04/schema",
  "title": "Base64",
  "description": "Base64 string",
  "type": "string",
  "pattern": "^(?:[A-Za-z0-9+\/]{4}\\n?)*(?:[A-Za-z0-9+\/]{2}==|[A-Za-z0-9+\/]{3}=)?$"
}