CryptoField::decrypt

public function decrypt($data)
{
	if ($this->encryptionComplete)
		return parent::decrypt($data);

	if($data == '')
		return $data;

	try
	{
		$value = base64_decode($data);
		if (false === $value) // not base64 decoded so not encrypted
			return $data;

		if (mb_strlen($value, 'latin1') <= $this->ivLength) // too short to be encrypted
			return $data;

		$value = static::$cipher->decrypt($value, $this->cryptoKey);
		return $value;
	}
	catch(SecurityException $e)
	{
		return $data;
	}
}