A Reversible Encryption Routine for PHP

By Tony Marston
2005-04-15

The ApplyFudgeFactor function

This function will return an adjustment value using the contents of the $fudgefactor array. Note that $fudgefactor is passed by reference so that it can be modified.

   function _applyFudgeFactor (&$fudgefactor) 

   {

Here we extract the first entry in the array and remove it from the array.

$fudge = array_shift($fudgefactor);

Next we add in the optional $adj value and put the result back into the end of the array.

$fudge = $fudge + $this->adj;

      $fudgefactor[] = $fudge;

If a $modulus value has been supplied we use it and possibly reverse the sign on the output value.

 if (!empty($this->mod)) {                   // if modifier has been supplied 

         if ($fudge % $this->mod == 0) {  // if it is divisible by modifier 

            $fudge = $fudge * -1;            // reverse then sign 

         } // if 

      } // if

There is no more 'fudging' left to do, so we can return the value to the calling process.

    return $fudge; 

       

   } // _applyFudgeFactor

Tutorial Pages:
» A Reversible Encryption Routine for PHP
» Rotating each character a fixed number of positions
» Swapping between two different character strings
» Manipulating the index number between the two strings
» Customising the Encryption Algorithm
» Class Variables
» Class Constructor
» The ConvertKey function
» The ApplyFudgeFactor function
» The CheckRange Function
» The Decrypt function
» Using the Encryption Class
» Summary

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