{
   "success": true|false,     // is the passcode valid, and does it meet security criteria you specified, e.g. sitekey?
   "challenge_ts": timestamp, // timestamp of the challenge (ISO format yyyy-MM-dd'T'HH:mm:ssZZ)
   "hostname": string,        // the hostname of the site where the challenge was passed
   "credit": true|false,      // optional: deprecated field
   "error-codes": [...]       // optional: any error codes
   "score": float,            // ENTERPRISE feature: a score denoting malicious activity.
   "score_reason": [...]      // ENTERPRISE feature: reason(s) for score.
}