[PHP Reverse Solution] http://w3.tbd.my/thread-14121-post-163114.html#pid163114

php_reverse_solution.php

#!/usr/bin/php

<?php
    // http://w3.tbd.my/thread-14121-post-163114.html#pid163114

    //$key = "3"; // 3 = 51, "=" = 61

    //echo "Original Algo: \n";
    //var_dump(algo2($key));

    //$var = base64_encode(str_rot13(implode('.', algo2($key))));
    //$var = algo2($key);
    $var = "MSwxLDU1LjgsMS41LDEzLjEsMSwxMy41NSwzNC4xLDAsMC41LDEzLjEsMCw1NS4xLDIsMS4zLDIuMSwx​LDEzLjEsMCw1LjEsMCwxLjMsMi41NSwzNC4xLDAsMS4xLDEsOC4xLDEsMTMuMywyLjgsMzQuNSwx";
    $test = str_rot13(base64_decode($var));
    $arr = explode(".", $test);

    for($i = 0; $i < sizeof($arr); $i++)
    {
        $encode_str[] = explode(",", $arr[$i]);
    }

    for($let_i = 0; $let_i < sizeof($encode_str); $let_i++)
    {
        for($let_j = 0; $let_j < sizeof($encode_str[$let_i]); $let_j++)
        {
            $encode_str[$let_i][$let_j] = rev_algo1((int)$encode_str[$let_i][$let_j]);
        }
    }

    for($let_i = 0; $let_i < sizeof($encode_str); $let_i++)
    {
        $ascii_str[] = implode('', $encode_str[$let_i]);
    }

    for($index = 0; $index < sizeof($ascii_str); $index++)
    {
        echo chr($ascii_str[$index]);
    }
    
    function algo2($v){
        $b = array();
        for($i = 0;$i < strlen($v); $i++){
            $b[] = ord($v[$i]);
        }
        
        $c = array();
        $d = array();
        $e = array();
        
        for($i = 0;$i < sizeof($b); $i++){
            $temp = "";
            $str = (string) $b[$i];

            for($j = 0;$j < strlen($str);$j++ ){
                $d[] = algo1((int) $str[$j]);
            }

            $c[] = implode(',',$d);
            $e[] = $d;
            unset($d);
        }

        //return $c;
        return base64_encode(str_rot13(implode('.',$c)));
    }
    
    function algo1($v){
        if(is_int($v)){
            switch($v){
                case 0:
                    return 0;
                break;
                case 1:
                    return 1;
                break;
                case 2:
                    return 2;
                break;
                default:
                    $tempa = 1;
                    $tempb = 2;
                    for($i = 2; $i < $v; $i++){
                        $tem = $tempb; // tem = b
                        $tempb = $tempa + $tempb; // a + b
                        $tempa = $tem; // a = b
                    }
                break;
            }
            return $tempb;
        }
        return false;
    }

    function rev_algo1($v){
        if(is_int($v)){
            switch($v){
                case 0:
                    return 0;
                break;
                case 1:
                    return 1;
                break;
                case 2:
                    return 2;
                break;
                default:
                    $count = 0;

                    $tempa = 1;
                    $tempb = 2;
                    for($i = 2; $i < $v; $i++){
                        $tem = $tempb; // tem = b
                        $tempb = $tempa + $tempb; // a + b
                        $tempa = $tem; // a = b

                        $count++;

                        if($tempb == $v)
                        {
                            $count = $count + 2; 
                            $i = $v;

                            return $count;
                        }
                    }
                break;
            }
            return $count;
        }
        return false;
    }
?>