RSA签名功能问题

function getCannedPolicy($resource, $expires, $key, $privatekeyfile){
         $priv_key = file_get_contents($privatekeyfile);
         $pkeyid = openssl_get_privatekey($priv_key);
         $policy_str = \'{\"Statement\":[{\"Resource\":\"\'.$resource.\'\",\"Condition\":{\"DateLessThan\":{\"AWS:EpochTime\":\'.$expires.\'}}}]}\';
         $policy_str = trim( preg_replace( \'/\\s+/\', \'\', $policy_str ) );
         $res = openssl_sign($policy_str, $signature, $pkeyid, OPENSSL_ALGO_SHA1);
         $signature_base64 = (base64_encode($signature));
         $repl = array(\'+\' => \'-\',\'=\' => \'_\',\'/\' => \'~\');
         $signature_base64 = strtr($signature_base64,$repl);
         $url = $resource . \'?Expires=\'.$expires. \'&Signature=\' . $signature_base64 . \'&Key-Pair-Id=\'. $key;

         return $url;
}

private function getCannedPolicy(resource:String, expires:uint, key:String, privatekey:String):String{          
    var unsigned:String = \'{\"Statement\":[{\"Resource\":\"\' +resource+ \'\",\"Condition\":{\"DateLessThan\":{\"AWS:EpochTime\":\' +expires+ \'}}}]}\';
    var signed:String = \'\';
    var signature:String = \'\';
    var regex:RegExp = /\\s+/g;          
    unsigned = unsigned.replace(regex,\'\');
    var src:ByteArray = new ByteArray();            
    src.writeUTFBytes(unsigned);            
    var dst:ByteArray = new ByteArray();            
    var hash:SHA1 = new SHA1();
    src = hash.hash(src);                       
    var rsa:RSAKey = PEM.readRSAPrivateKey(privatekey);
    trace(rsa.dump());
    rsa.sign(src, dst, src.length);
    dst.position = 0;           
    signature = Base64.encodeByteArray(dst);                            
    signature = signature.split(\"+\").join(\"-\");
    signature = signature.split(\"=\").join(\"_\");
    signature = signature.split(\"\\/\").join(\"~\");
    signed = resource+\'?Expires=\' +expires+ \'&Signature=\' +signature+ \'&Key-Pair-Id=\' +key; 

    return signed;
}