function encode($plaintext, $key)
{
$encryptedText = "";
$cleanText = clean($plaintext);
$paddedText = padText($cleanText, $key);
$counter = 0;
for ($i = 0; $i < $key; $i++) {
$encryptedText .= $paddedText[$i];
for ($j = $i + 1; $j < strlen($paddedText); $j++) {
$counter++;
if ($counter % $key == 0) {
$encryptedText .= $paddedText[$j];
$counter = 0;
}
}
$counter = 0;
}
return $encryptedText;
}
function encode($plaintext, $key, $sizeOfKey)
{
$encryptedText = "";
$cleanText = clean($plaintext);
$paddedText = padText($cleanText, $key, $sizeOfKey);
$paddedTextArray = explode(",", $paddedText);
$keyArray = explode(",", $key);
array_splice($keyArray, 0, 1);
// Moves through text one block at a time, converts it to the 0-25 value system,
// multiples key row against block as a column, mods by 26, then adds 97 to convert
// back to ascii letter.
for ($x = 0; $x < count($paddedTextArray); $x += $sizeOfKey) {
$plainBlock = array();
// Collects a block and converts to the 0-25 value.
for ($y = 0; $y < $sizeOfKey; $y++) {
array_push($plainBlock, $paddedTextArray[$x + $y]);
}
// Traverses the whole key, one row after the next.
for ($p = 0; $p < $sizeOfKey * $sizeOfKey; $p += $sizeOfKey) {
$letterTotal = 0;
// Collects the sum of products of a key row and plaintext block column.
for ($z = 0; $z < $sizeOfKey; $z++) {
$letterTotal += $keyArray[$p + $z] * $plainBlock[$z];
}
// Converts 0-25 value of encrypted letter back into ascii equivalent.
if ($letterTotal >= 0) {
$encryptedText .= NumToLetter($letterTotal % 26);
} else {
$result = $letterTotal;
while ($result < 0) {
$result += 26;
}
$encryptedText .= NumToLetter($result);
}
}
}
return $encryptedText;
}