Verschiebechiffre

<?php

/*



Verschiebechiffre.

Chiffriert einen String mit einem Passwort, mit selbigen (Naja, nicht ganz...) lässt sich wieder entschlüsseln.

Funktioniert nur mit ASCII!



Copyright (C) 2006  Basilius Sauter



This library is free software; you can redistribute it and/or

modify it under the terms of the GNU Lesser General Public

License as published by the Free Software Foundation; either

version 2.1 of the License, or (at your option) any later version.



This library is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

Lesser General Public License for more details.



You should have received a copy of the GNU Lesser General Public

License along with this library; if not, write to the Free Software

Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA



*/



function shiftcipher_encode($sEncode, $sPass) {

  $iPass = (crc32($sPass)%256);

  $iEncodeLenght = StrLen($sEncode);

  $sCrypt = '';

  

  for($i = 0; $i < $iEncodeLenght; $i++) {

	  $iAsciiVal = ord($sEncode{$i});

	  $iAsciiVal += $iPass;

	  while($iAsciiVal > 255) {

		  $iAsciiVal -= 256;

		}

		

		$sCript .= chr($iAsciiVal);

	}

  

  return $sCript;

}



function shiftcipher_decode($sDecode, $sPass) {

	$iPass = (crc32($sPass)%256);

  $iDecodeLenght = StrLen($sDecode);

	$sDecript = '';

	

	for($i = 0; $i < $iDecodeLenght; $i++) {

	  $iAsciiVal = ord($sDecode{$i});

	  $iAsciiVal -= $iPass;

	  while($iAsciiVal > 255) {

		  $iAsciiVal -= 256;

		}

		

		$sDecript .= chr($iAsciiVal);

	}

  

  return $sDecript; 

}





$var = shiftcipher_encode('Hello World', 'bla';

$var2 = shiftcipher_decode($var, 'bla';



var_dump($var, $var2);



?>

string(11) "ž¥¥¨Y¨«¥"

string(11) "Hello World"