private int registerChallenge() {
		try {
			String GET_URL = apiUrl + registerUrl+"?gt=" + this.captchaId;
			if (this.userId != ""){
				GET_URL = GET_URL + "&user_id=" + this.userId;
				this.userId = "";
			}
			gtlog("GET_URL:" + GET_URL);
			String result_str = readContentFromGet(GET_URL);
			gtlog("register_result:" + result_str);
			if (32 == result_str.length()) {

				this.responseStr = this.getSuccessPreProcessRes(this.md5Encode(result_str + this.privateKey));
				
				return 1;
			} else {
				gtlog("gtServer register challenge failed");
				return 0;
			}
		} catch (Exception e) {
			gtlog("exception:register api");
		}
		return 0;
	}