A string specifying the encryption key. The default is a null reference (Nothing in Visual Basic) meaning no encryption.
All connections must use the same key as was specified when the database was created. Lost or forgotten keys result in completely
As with all passwords, it is best to choose a key value that cannot be easily guessed. The key can be of arbitrary length,
but generally the longer the key, the better, because a shorter key is easier to guess than a longer one. Using a combination
of numbers, letters, and special characters decreases the chances of someone guessing the key.