/**
* @return string
*/
public function __debugInfo()
{
return ['value' => self::SAFE_OUTPUT, 'bytes' => ByteString::strlen($this->value)];
}
/**
* @param string $encrypted
*
* @throws CryptoException
*
* @return string
*/
public function decrypt($encrypted)
{
if (!$encrypted || !is_string($encrypted)) {
throw new CryptoException(sprintf(self::ERR_CANNOT_DECRYPT, gettype($encrypted)));
}
// Sanity check size of payload is larger than MAC + NONCE
if (ByteString::strlen($encrypted) < self::NONCE_SIZE_BYTES + \Sodium\CRYPTO_AUTH_BYTES) {
throw new CryptoException(self::ERR_SIZE);
}
// Split into nonce, mac, and encrypted payload
$nonce = ByteString::substr($encrypted, 0, self::NONCE_SIZE_BYTES);
$mac = ByteString::substr($encrypted, self::NONCE_SIZE_BYTES, \Sodium\CRYPTO_AUTH_BYTES);
$encrypted = ByteString::substr($encrypted, self::NONCE_SIZE_BYTES + \Sodium\CRYPTO_AUTH_BYTES);
// Verify MAC
try {
$isVerified = \Sodium\crypto_auth_verify($mac, $nonce . $encrypted, $this->authSecret->getValue());
} catch (Exception $ex) {
throw new CryptoException(sprintf(self::ERR_DECODE_UNEXPECTED, $ex->getMessage()), $ex->getCode(), $ex);
}
if (!$isVerified) {
throw new CryptoException(self::ERR_DECODE);
}
// Decrypt authenticated payload
try {
$unencrypted = \Sodium\crypto_secretbox_open($encrypted, $nonce, $this->cryptoSecret->getValue());
} catch (Exception $ex) {
throw new CryptoException(sprintf(self::ERR_DECRYPT, $ex->getMessage()), $ex->getCode(), $ex);
}
return $unencrypted;
}
/**
* Validates the given string is a correct byte stream for a GUID.
*
* This does some seemingly crazy things, but basically it validates that the given value will be within the set
* of possible GUID's that GUID::create() can produce.
*
* @param string $guid
*
* @return bool
*/
private static function validate($guid)
{
if (ByteString::strlen($guid) !== 16) {
return false;
}
$byte = $guid[6];
$byte = (ord($byte) & 0xf0) >> 4;
if ($byte !== 4) {
return false;
}
$byte = $guid[8];
$byte = ord($byte) & 0xc0;
if ($byte !== 0x80) {
return false;
}
return true;
}