<?php;;
$key = "This is supposed to be a secret key !!!";;;

function keyED($txt,$encrypt_key);;
{;;
$encrypt_key = md5($encrypt_key);;;
$ctr=0;;;
$tmp = "";;;
for ($i=0;$i<strlen($txt);$i++);;
{;;
if ($ctr==strlen($encrypt_key)) $ctr=0;;;
$tmp.= substr($txt,$i,1) ^ substr($encrypt_key,$ctr,1);;;
$ctr++;;;
};;
return $tmp;;;
};;

function encrypt($txt,$key);;
{;;
srand((double)microtime()*1000000);;;
$encrypt_key = md5(rand(0,32000));;;
$ctr=0;;;
$tmp = "";;;
for ($i=0;$i<strlen($txt);$i++);;
{;;
if ($ctr==strlen($encrypt_key)) $ctr=0;;;
$tmp.= substr($encrypt_key,$ctr,1) .;;
(substr($txt,$i,1) ^ substr($encrypt_key,$ctr,1));;;
$ctr++;;;
};;
return keyED($tmp,$key);;;
};;

function decrypt($txt,$key);;
{;;
$txt = keyED($txt,$key);;;
$tmp = "";;;
for ($i=0;$i<strlen($txt);$i++);;
{;;
$md5 = substr($txt,$i,1);;;
$i++;;;
$tmp.= (substr($txt,$i,1) ^ $md5);;;
};;
return $tmp;;;
};;

$string = "Hello World !!!";;;

// encrypt $string, and store it in $enc_text;;
$enc_text = encrypt($string,$key);;;

// decrypt the encrypted text $enc_text, and store it in $dec_text;;
$dec_text = decrypt($enc_text,$key);;;

print "Original text : $string <Br>n";;;
print "Encrypted text : $enc_text <Br>n";;;
print "Decrypted text : $dec_text <Br>n";;;
?>;;

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