newSecretKey method
Generates a new SecretKey.
It will have the correct length (secretKeyLength).
The source of random bytes is Random.secure (a cryptographically secure random number generator) unless a custom random number generator was specified when you constructed the cipher (or your Cryptography instance).
Implementation
Future<SecretKey> newSecretKey() async {
return SecretKeyData.random(
length: secretKeyLength,
random: random,
);
}