<?php
/**************************************
    Usage:
     function CryptAlg($dString,$dKey,$dType,$dIntense,$dCalcNum)
     * Where:
     $dString is the string you wish to encrypt
     $dKey is your encryption key
     $dType is to encrypt or decrypt the string ($dType values are 0 or 1,
        0 is encrypt and 1 is decrypt)
     $dIntense is how many times you wish to encrypt the
        string (makes for a more secure and harder to break string)
        Since the highest ascii value for a text character is 255, if
        you set the $dIntense value to 255, it will just loop back to
        where it was, and intern decrypt what you encrypted.
     $dCalcNum is the number that will be added or subtracted with when
        ever encryption begins. The math will take place and will affect
        the first ascii number in the two statements.
    Notes:
     When crypting a string, remember that you MUST have the exact
     same $dKey, $dIntense, and $dCalcNum variables as the encrypted
     or decrypted string for it to accurately do it's job.

*/
    function CryptAlg($dString,$dKey,$dType,$dIntense,$dCalcNum)
    {
        $dString = str_replace(" ","",str_replace("-","",$dString));
        if ($dIntense > 254)
            $dIntense = 254;
        $dNewString = $dString;
        for ($y = 0; $y <= $dIntense; $y++)
        {
            $strOutput = "";
            $x = 0;
            for ($i = 0; $i < strlen($dNewString); $i++)
            {
                if ($x >= strlen($dKey))
                    $x = 0;
                if ($dType == 0)
                    $strOutput .= Chr((Ord($dNewString[$i]) + $dCalcNum) - Ord($dKey[$x]));
                if ($dType == 1)
                    $strOutput .= Chr((Ord($dNewString[$i]) - $dCalcNum) + Ord($dKey[$x]));
                $x++;
            }
            $dNewString = $strOutput;
        }
        return $dNewString;
    }

    # GLOBAL CREDITCARD ENCRYPTION KEY/CALCNUM
    $dKey = "SkeletonKey";
    $dIntense = 1;
    $dCalcNum = 1234567890;

    /*$test = CryptAlg("Crypt Algorithm", "testkey1234567890", 0, 110, 1234567890);
    echo "Encrypted text: $test<br>";
    $test = CryptAlg($test, "testkey1234567890", 1, 110, 1234567890);
    echo "Decrypted text: $test<br>";*/
?>