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Simple file shredder in PHP

Posted May 10th, 2007 by Mgccl

in

File shredding is used to destroy the data written on the disk. Usually rewrite the data once is enough to destroy the data, but for extreme measure, use super strong magnetic field.
The function I wrote below WORKS ONLY IF new data is written directly on top of the original file. This will be determined by your file system, and I don't know which file system works, but I know that NFS or Journaling file systems does not work.

function shred($filename,$strength=1,$fast=null){
	$size = filesize($filename);
 
	while($i < $strength){
		$fh = fopen($filename,'w');
		if($fast){
		$str = chr(rand(0,255));
			$str = str_repeat($str,$size);
		}else{
			$str = md5(rand(0,2147483647));
			$n = 32;
			while($n<$size){
				$str .= md5($str);
				$n+=32;
			}
		}
 
		fwrite($fh,substr($str,0,$size));
		fclose($fh);
		++$i;
	}
	return true;
}