Pulls the cipher signature decipher JS code from youtube. Youtube protects its videos using a cipher signature ,which is decoded by player before playing so to decrypt the cipher use the code below code to get the cipher code from YouTube and run it in WebView or JavaScript engine to decipher the signature. Demo : http://detectivec.de/ytcipher.php

YTCipher.php

<?php

function startsWith ($string, $startString) 
{ 
    $len = strlen($startString); 
    return (substr($string, 0, $len) === $startString); 
}


$url="https://www.youtube.com/";

//$regex_player="/(?<=ytplayer.config\s=).*?(\})(?=;)/m";



$regex_player_url="/(?<=PLAYER_JS_URL\":\").*?(?=\")/m";
$regex_desipher_function_code="/\\{[a-zA-Z]{1,}=[a-zA-Z]{1,}.split\\(\"\"\\);[a-zA-Z0-9$]{2}\\.[a-zA-Z0-9$]{2}.*?[a-zA-Z]{1,}.join\\(\"\"\\)\\};/s";
$regex_var_name="/[a-zA-Z0-9$]{2}\\.[a-zA-Z0-9$]{2}\\([a-zA-Z]\\,(\\d\\d|\\d)\\)/s";
    

$source=file_get_contents($url);
preg_match($regex_player_url, $source, $matches, PREG_OFFSET_CAPTURE, 0);
$player_url=str_replace("\\","" ,urldecode($matches[0][0]));


if(!startsWith($player_url,"wwww") || !startsWith($player_url,"http")){
    $player_url="https://www.youtube.com".$player_url;
}


$js= file_get_contents($player_url);


preg_match($regex_desipher_function_code, $js, $ds_fun, PREG_OFFSET_CAPTURE, 0);

preg_match($regex_var_name, $ds_fun[0][0], $var_name, PREG_OFFSET_CAPTURE, 0);
$var_name=str_replace("$","\\$",$var_name[0][0]);

$varname=explode(".",$var_name);
$regex_var_code = "/var\\s" . $varname[0] . "=.*?\\};/s";
preg_match($regex_var_code, $js, $var_code, PREG_OFFSET_CAPTURE, 0);


$decipher_fun="decipher=function(a)".$ds_fun[0][0]."\n\n".$var_code[0][0];

echo ($decipher_fun);

?>