Locally trying to decrypt a binary file with the given ciper. The data separated with 0A in hexadecimal. In the decrypting phase my array works like an int, and I do not know why. Is there a proper solution to it?

• php version:8.0.11

• tried to reinstall xampp

• tried castings

   <?php
           if(count($_POST)>0)
           {
  
               $ciper = array(5, -14, 31, -9, 3);
  
               $dec_arr = [];
               $ind = 0;
               $handle = fopen("secret.txt", "r");
               if ($handle) {
                   while (!feof($handle)) {
                       $hex = bin2hex(fread ($handle , 1 ));
                       $dec_arr[$ind] = hexdec($hex);
                       $ind  ;
                   }
                   fclose($handle);
               }
               unset($dec_arr[(count($dec_arr)-1)]);                   
  
               $raw_data = "";
               for($i = 0, $k = 0; $i < count($dec_arr); $i  )//Warning: Trying to access array offset on value of type int
               {                           
                   if($dec_arr[$i]==10)
                   {
                       $dec_arr[$i] = 59;
                       $k = 0;
                   }
                   else
                   {
                       $dec_arr = ((($dec_arr[$i]   256) - $ciper[$k])%256);//Fatal error: Uncaught TypeError: count(): Argument #1 ($value) must be of type Countable|array, int given
                   }
                   $raw_data .= chr($dec_arr[$i]);
                   $k = (($k 1)%5);                    
               }
           }?>
  

CodePudding user response：

Like @aynber mentioned you are assigning an int value to the $dev_arr. Your line should be

$dec_arr[$i] = ((($dec_arr[$i]   256) - $ciper[$k])%256);

Also you could replace

unset($dec_arr[(count($dec_arr)-1)]);

with

array_pop($dec_arr);