问机器翻译报错AuthFailure.SignatureFailure？

<?php
header('Content-type:text/html; Charset=utf-8');
$SecretId = 'xxx';
$SecretKey = 'xxx';
$uriData = 'tmt.tencentcloudapi.com';

$SourceText = "hello world!";
$Source = "en";
$Target = "zh";
$region = 'ap-chengdu';

$test = new fanyi($SecretId, $SecretKey, $uriData);
$ret = $test->translate($SourceText, $Source, $Target, $region);

$ret = json_decode($ret, true);
print_r($ret);

class fanyi {
	protected $SecretId;
	protected $SecretKey;
	public function __construct($SecretId, $SecretKey, $uriData) {
		$this->SecretId = $SecretId;
		$this->SecretKey = $SecretKey;
		$this->uriData = $uriData;
	}
	public function translate($SourceText, $Source, $Target, $region) {
		$arr = array(
			'Action' => 'TextTranslate',
			'ProjectId' => 0,
			'Region' => $region,
			'SecretId' => $this->SecretId,
			'SourceText' => urlencode($SourceText),
			'Source' => $Source,
			'Target' => $Target,
			'Nonce' => mt_rand(10000, 99999),
			'Timestamp' => time(),
			'Version' => '2018-03-21'
		);
        $arr['Signature'] = urlencode(self::sign($this->uriData, $arr, $this->SecretKey));
		print_r($arr);
		return self::curlPost("https://$this->uriData", $arr);
	}
	public static function sign($uriData, $params, $SecretKey){
		ksort($params, SORT_STRING);
		$params = http_build_query($params);
		$srcStr = "$uriData/?$params";
		$signStr = base64_encode(hash_hmac('sha1', $srcStr, $SecretKey, true));
		return $signStr;
	}
	public static function curlPost($url = '', $postData = '', $options = array()) {
		if (is_array($postData)) {
			$postData = http_build_query($postData, true);
		}
		$ch = curl_init();
		curl_setopt($ch, CURLOPT_URL, $url);
		curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
		curl_setopt($ch, CURLOPT_POST, 1);
		curl_setopt($ch, CURLOPT_POSTFIELDS, $postData);
		curl_setopt($ch, CURLOPT_TIMEOUT, 30);
		if (!empty($options)) {
			curl_setopt_array($ch, $options);
		}
		curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
		curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);
		$data = curl_exec($ch);
		curl_close($ch);
		return $data;
	}
}