generateRandomString function
Generates a secure random string of the specified length.
The resulting String is base64 encoded and capped at length,
and thus has a lower entropy than length bytes.
Implementation
String generateRandomString([int length = 32]) {
var values = List<int>.generate(length, (int i) => _random.nextInt(256));
return base64Url.encode(values).substring(0, length);
}