Trying to make a low level encryption

[Napster]

I am trying to make a low level encryption, my current code for it is...

<?php

function encryption($string, $char='e') {

  $array = array(A => "m", B=>"F", C=>"t", D=>"K", E=>"3", F=>"Q", G=>"2", H=>"z", I=>"c", J=>"A", K=>"i", L=>"x", M=>"0",

             N=>"Z", O=>"a", P=>"L", Q=>"p", R=>"H", S=>"7", T=>"1", U=>"e", V=>"T", W=>"g", X=>"l", Y=>"C", Z=>"W",

		     a=>"B", b=>"f", c=>"O", d=>"w", e=>"r", f=>"y", g=>"5", h=>"o", i=>"G", j=>"X", k=>"u", l=>"k", m=>"9",

		     n=>"v", o=>"J", p=>"R", q=>"S", r=>"b", s=>"D", t=>"N", u=>"P", v=>"6", w=>"q", x=>"S", y=>"h", z=>"E",

		     1=>"I", 2=>"V", 3=>"Y", 4=>"d", 5=>"4", 6=>"8", 7=>"M", 8=>"j", 9=>"U", 0=>"n", " "=>"ß", "ß"=>" "

			);

  for ($x = 0; $x < strlen($string); $x++) {

if ($char == 'e') $replace = $array[$string[$x]];

if ($char == 'd') { foreach ($array as $key=>$value) { if ($value == $string[$x]) { $replace = $key; } } }

$string[$x] = str_replace($string[$x], $replace, $string[$x]);

  }

  return $string;

}

?>

Now my code to use it is...

   $e = encryption("Hello World, My Name is Josh Weißböck");

   $d = encryption($e, 'd');

   $content = "Encrypted: $e<br>Decrypted: $d";

Now echoing the variable this is what I get for a result...

Encrypted: zrkkJßgJbkwß0hßZB9rßGDßAJDoßgrG fOu
Decrypted: Hello Worldd My Name is Josh Weißbbck

Which is not exactly the same, and I can not figure out how to get it to work correctly.

[goaman]

Hi!
try this simple encryption/decryption:

//encrypt
function encrypt($string, $key) {
   $result = '';
   for($i=0; $i<strlen($string); $i++) {
     $char = substr($string, $i, 1);
     $keychar = substr($key, ($i % strlen($key))-1, 1);
     $char = chr(ord($char)+ord($keychar));
     $result.=$char;
   }

   return base64_encode($result);
  }




//decrypto
  function decrypt($string, $key) {
   $result = '';
   $string = base64_decode($string);

   for($i=0; $i<strlen($string); $i++) {
     $char = substr($string, $i, 1);
     $keychar = substr($key, ($i % strlen($key))-1, 1);
     $char = chr(ord($char)-ord($keychar));
     $result.=$char;
   }

   return $result;
  }



$test = encrypt("Hello Worldd My Name is Josh Weißbbck", "MYKEY");
echo $test;

$back = decrypt($test, "MYKEY");
echo $back;

[Weedpacket]

Well, once you've made one change, any code letters risk being mistaken for original letters and being changed again. If you've got a rule that turns "A" to "B" and a rule that turns "B" to "C", then if you do the first one first and then the second, "A" becomes "B" becomes "C".

But if you're changing single characters for single characters, look at [man]strtr[/man].

function encryption($string, $char='e')
{
	$from = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890 ß';
	$to = 'mFtK3Q2zcAix0ZaLpH71eTglCWBfOwry5oGXuk9vJRSbDNP6qShEIVYd48MjUnß ';
	if($char=='e')
		return strtr($string, $from, $to);
	elseif($char=='d')
		return strtr($string, $to, $from);
	else
	{
		// Errrr... maybe just pass a boolean instead of a character?
	}
}

Incidentally, I can tell you don't develop with error reporting set to E_ALL.

[Napster]

Just to let you know, the char parameter is to tell the function if I am going to encrypt or decrypt the string parameter. The array array is what the letters should be converted into when encrypted and changed back to when decrypted.

[Weedpacket]

Yeah, I figured that, but why use a whole char and therefor at least one and sometimes two string comparisons?

function encryption($string, $encrypt=true)
{
    $from = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890 ß';
    $to = 'mFtK3Q2zcAix0ZaLpH71eTglCWBfOwry5oGXuk9vJRSbDNP6qShEIVYd48MjUnß ';
    if($encrypt)
        return strtr($string, $from, $to);
    else
        return strtr($string, $to, $from);
}