<?php
function changedataout($cipher_data,$key){
$m=0;
$all_bin_chars="";
for($i=0;$i<strlen($cipher_data);$i++){
$c=substr($cipher_data,$i,1); // c = ciphertext
$decimal_value=base64todec($c); //convert to decimal value
$decimal_value=($decimal_value - $m) / 4; //substract by m where m=0,1,2,or 3 then divide by 4
$four_bit=decbin($decimal_value);
while(strlen($four_bit)<4){
$four_bit="0".$four_bit;
}
$all_bin_chars=$all_bin_chars.$four_bit;
$m++;
if($m>3){
$m=0;
}
}
$key_length=0;
$plain_data="";
for($j=0;$j<strlen($all_bin_chars);$j=$j+8){
$c=substr($all_bin_chars,$j,8);
$k=substr($key,$key_length,1);
$dec_chars=bindec($c);
$dec_chars=$dec_chars - strlen($key);
$c=chr($dec_chars);
$key_length++;
if($key_length>=strlen($key)){
$key_length=0;
}
$dec_chars=ord($c)^ord($k);
$p=chr($dec_chars);
$plain_data=$plain_data.$p;
}
return $plain_data;
}
function base64todec($base64_value){
// convert base64 value into decimal value
switch($base64_value){
case "A":$decimal_value=0;break;
case "B":$decimal_value=1;break;
case "C":$decimal_value=2;break;
case "D":$decimal_value=3;break;
case "E":$decimal_value=4;break;
case "F":$decimal_value=5;break;
case "G":$decimal_value=6;break;
case "H":$decimal_value=7;break;
case "I":$decimal_value=8;break;
case "J":$decimal_value=9;break;
case "K":$decimal_value=10;break;
case "L":$decimal_value=11;break;
case "M":$decimal_value=12;break;
case "N":$decimal_value=13;break;
case "O":$decimal_value=14;break;
case "P":$decimal_value=15;break;
case "Q":$decimal_value=16;break;
case "R":$decimal_value=17;break;
case "S":$decimal_value=18;break;
case "T":$decimal_value=19;break;
case "U":$decimal_value=20;break;
case "V":$decimal_value=21;break;
case "W":$decimal_value=22;break;
case "X":$decimal_value=23;break;
case "Y":$decimal_value=24;break;
case "Z":$decimal_value=25;break;
case "a":$decimal_value=26;break;
case "b":$decimal_value=27;break;
case "c":$decimal_value=28;break;
case "d":$decimal_value=29;break;
case "e":$decimal_value=30;break;
case "f":$decimal_value=31;break;
case "g":$decimal_value=32;break;
case "h":$decimal_value=33;break;
case "i":$decimal_value=34;break;
case "j":$decimal_value=35;break;
case "k":$decimal_value=36;break;
case "l":$decimal_value=37;break;
case "m":$decimal_value=38;break;
case "n":$decimal_value=39;break;
case "o":$decimal_value=40;break;
case "p":$decimal_value=41;break;
case "q":$decimal_value=42;break;
case "r":$decimal_value=43;break;
case "s":$decimal_value=44;break;
case "t":$decimal_value=45;break;
case "u":$decimal_value=46;break;
case "v":$decimal_value=47;break;
case "w":$decimal_value=48;break;
case "x":$decimal_value=49;break;
case "y":$decimal_value=50;break;
case "z":$decimal_value=51;break;
case "0":$decimal_value=52;break;
case "1":$decimal_value=53;break;
case "2":$decimal_value=54;break;
case "3":$decimal_value=55;break;
case "4":$decimal_value=56;break;
case "5":$decimal_value=57;break;
case "6":$decimal_value=58;break;
case "7":$decimal_value=59;break;
case "8":$decimal_value=60;break;
case "9":$decimal_value=61;break;
case "+":$decimal_value=62;break;
case "/":$decimal_value=63;break;
case "=":$decimal_value=64;break;
default: $decimal_value=0;break;
}
return $decimal_value;
}
?>
; the decryption file i got from a hacker like person . and i have been challanged to decrypt .
