index.php

<?php

/**
 * Author: Akhilesh Chandra Gupta
 * Author URI: http://www.bitnol.com
 * API URI: http://api.gitnol.com
 * Description: Demo of the application of Cipher API
 * License: MIT License
 */

	// Youtube Video ID 	
	if(isset($_GET['id']) && $_GET['id'] != ""){
		$video_id = $_GET['id'];
	}else{
		echo 'video id not provided';
		exit;
	}

	$CipherAPIkey = "Enter your Cipher apikey here";
	
	// get_video_info url formation
	// although for cipher signature we have to get the details from the video's webapge not from get_video_info object
	$info_url = "http://www.youtube.com/get_video_info?video_id=".$video_id."&el=vevo&el=embedded&hl=en_US";
	
	// youtube webpage url formation
	$yt_url = 'http://www.youtube.com/watch?v='.$video_id.'&gl=US&persist_gl=1&hl=en&persist_hl=1';;

	// get the contents from the url
	$raw_data = file_get_contents($info_url);
	
	// parse the data received and save it as an array
	$output = array();
	parse_str($raw_data,$output);

	// check the status of the get_video_info object
	if($output['status']=='ok'){
		
		// check for the cipher signature
		$cipher = (isset($output['use_cipher_signature']) &&  $output['use_cipher_signature']=='True') ? true : false;

			// if cipher is true then we have to change the plan and get the details from the video's youtube wbe page
			$yt_html = file_get_contents($yt_url);
			
			// parse for the script containing the configuration
			preg_match('/ytplayer.config = {(.*?)};/',$yt_html,$match);
			$yt_object = @json_decode('{'.$match[1].'}') ;

			/// check if we are able to parse data
			if(!is_object($yt_object)){
				echo 'Sorry! Unable to parse Data';
			}else{
				
				// parse available formats
				$formats = $yt_object->args->url_encoded_fmt_stream_map;
				// get the player id from assets section
				$player_id = strbtwn($yt_object->assets->js,'html5player-','.js');
				$player_id = explode("/", $player_id);
				$player_id = $player_id[0];
				
				echo 'Player ID: '.$player_id.'<br /><hr />';
								
				// get the algo dictionary
				// first check if the file exists
				if(file_exists('./algo.json'))
					$algos = json_decode(file_get_contents('algo.json'),true);
				else{
					// API call to fetch the algo dictionary
					$algos_dict = file_get_contents("http://api.gitnol.com/v4/getAlgo.php?playerID=".$player_id."&apikey=".$CipherAPIkey);
					
					// saving the algo dictonary in local env for easy access
					// Note: Developers should save the dictionary in their local env. 
					// Only make the API call for the new player ids which is not present in the algo dictionary.
					// Repeated violation will results in IP ban.
					file_put_contents('algo.json', $algos_dict);
					
					$algos = json_decode($algos_dict,true);
				}

				/// check if the algo exist for the given player id
				if(!array_key_exists($player_id, $algos)){
					
					// if the algo dictionary is old then fetch a new one
					$algos_dict = file_get_contents("http://api.gitnol.com/v4/getAlgo.php?playerID=".$player_id."&apikey=".$CipherAPIkey);
					file_put_contents('algo.json', $algos_dict);
					
					$algos = json_decode($algos_dict,true);
					$algo = $algos[$player_id][1];
					 
				}else{
					$algo = $algos[$player_id][1];
				}
				if($cipher){
					echo 'Algo Used: '.$algo.'<br /><hr />';
				} else {
					echo 'Non-Cipher<br /><hr />';
				}				
							
				// download links formation
				$dlinks = array();
				$links  = explode(',',$formats);
				
				echo 'Download links <br /><br />';
				
				foreach ($links as $link) {
					parse_str($link,$linkarr);
					// parse link array one by one and decrypt the signature
					// If cipher is true then we have to decode it
					if($cipher){
						$dlinks[$linkarr['itag']] = $linkarr['url'] . "&signature=" . decrypt($linkarr['s'],$algo);
					}else{
						if(!isset($linkarr['sig']) || !isset($linkarr['s']))
							$dlinks[$linkarr['itag']] = $linkarr['url'];
						else
							$dlinks[$linkarr['itag']] = $linkarr['url'] . "&signature=" . isset($linkarr['s']) ? $linkarr['s'] : $linkarr['sig'];
					}					
					echo $linkarr['itag'].'<br />';
					echo $dlinks[$linkarr['itag']].'<br /><br />';
				}
				echo '<hr />';
			}		
	}else{
		echo 'Unable to get Video Info';
	}
	
	// string helper function
	function strbtwn($content,$start,$end){
		$r = explode($start, $content);
		if (isset($r[1])){
			$r = explode($end, $r[1]);
			return $r[0];
		}
		return '';
	}
	
	// signature decoding 
	function decryptv3($sig, $algo){
		$dsig = '';
		foreach($algo as $key => $value){
			$dsig .= $sig[$value];
		}
		return $dsig;
	}
?>