90) {
$rand += 6;
}
$codeword .= chr($rand);
}
return $codeword;
}
function getLetterValue($char) {
return ord($char) - 33;
}
function getNumberValue($nr) {
return chr((($nr + 94) % 94) + 33);
}
function encodeChar($char, $offset) {
return getNumberValue(getLetterValue($char) + getLetterValue($offset));
}
function decodeChar($char, $offset) {
return getNumberValue(getLetterValue($char) - getLetterValue($offset));
}
function encode($codeword, $message) {
$encrypted = "";
for ($i = 0; $i < strlen($message); $i++) {
$encrypted .= encodeChar(substr($message, $i, 1), substr($codeword, $i % strlen($codeword), 1));
}
return $encrypted;
}
function hideCodeword($codeword, $message) {
$len = strlen($codeword);
$hidden = "";
for ($i = 0; $i < $len; $i++) {
$hidden .= substr($message, $i, 1);
$hidden .= substr($codeword, $i, 1);
}
$hidden .= substr($message, $len, strlen($message) - $len - 1);
$hidden .= chr(64 + $len);
$hidden .= substr($message, -1);
return $hidden;
}
function encrypt($message) {
$cw = generateCodeword(rand(7, 14));
return hideCodeword($cw, encode($cw, $message));
}
function decrypt($code) {
$len = ord(substr($code, -2, 1)) - 64;
$code = substr($code, 0, -2) . substr($code, -1);
$codedMessage = "";
$codeword = "";
for ($i = 0; $i < (2 * $len); $i += 2) {
$codedMessage .= substr($code, $i, 1);
$codeword .= substr($code, $i + 1, 1);
}
$codedMessage .= substr($code, 2 * $len);
$decrypted = "";
for ($i = 0; $i < strlen($codedMessage); $i++) {
$decrypted .= decodeChar(substr($codedMessage, $i, 1), substr($codeword, $i % strlen($codeword), 1));
}
return $decrypted;
}
?>
Encryption/Decryption tool