问我要提交转码任务，为什么一直就提示身份验证失败？

<?php
//header('Content-type:text/json'); 

$fileId = $_REQUEST['fileId'];

echo $fileId;
echo '<br>';


// 确定 App 的云 API 密钥
$secret_id = "AKIDwgAU2Jq1UcV8Ucs65sKVP2OTO2ThQJD1";
$secret_key = "xuc7YmTuoY6RcXBcquMax6yZu2OWN5tQ";


// 确定签名的当前时间和失效时间
$current = time();
$expired = $current + 86400;  // 签名有效期：1天
$num = rand(10000000, 100000000);

// 向参数列表填入参数
$arg_list = array(
    "secretId" => $secret_id,
    "currentTimeStamp" => $current,
    "expireTime" => $expired,
    "random" => rand());

// 计算签名
$orignal = http_build_query($arg_list);
$signature = base64_encode(hash_hmac('SHA1', $orignal, $secret_key, true).$orignal);

		$uri = "https://vod.api.qcloud.com/v2/index.php";
		// 參数数组
		$natvie = array (
				'Action' => 'ConvertVodFile',
				'fileId' => $fileId,
				'isScreenshot' => '0',
				'isWatermark' => '0',
				'Region' => 'bj',
				'Timestamp' => $current,
				'Nonce' => $num,
				'SecretId'=>$secret_id
		);
		ksort($natvie);
		$srcStr = 'POSTvod.api.qcloud.com/?';
		foreach ($natvie as $key => $val) {
			$srcStr = $srcStr . $key . "=" . $val . "&";
		};
		$srcStr1 = '';
		if(substr($srcStr,-1) == '&'){
			$srcStr1 = substr($srcStr,0,-1);
		}else{
			$srcStr1 = $srcStr;
		}
		
		
		echo $srcStr;
		echo '<br>';
		echo $srcStr1;
		echo '<br>';
		$signStr = base64_encode(hash_hmac('SHA1', $srcStr1, $secret_key, true));
		echo $signStr;
		echo '<br>';
		
		
		$data = array (
				'Action' => 'ConvertVodFile',
				'fileId' => $fileId,
				'isScreenshot' => '0',
				'isWatermark' => '0',
				'Region' => 'bj',
				'Timestamp' => $current,
				'Nonce' => $num,
				'SecretId'=>$secret_id,
				'Signature'=> $signStr
		);
		 
		$ch = curl_init ();
		//print_r($ch);
		curl_setopt ( $ch, CURLOPT_URL, $uri );
		curl_setopt ( $ch, CURLOPT_POST, 1 );
		curl_setopt ( $ch, CURLOPT_HEADER, 0 );
		curl_setopt ( $ch, CURLOPT_RETURNTRANSFER, 1 );
		curl_setopt ( $ch, CURLOPT_POSTFIELDS, $data );
	    $return = curl_exec ( $ch );
		
		curl_close ( $ch );
		die($return);
?>