generateKey function
Implementation
Uint8List generateKey(Uint8List salt, Uint8List passphrase){
KeyDerivator derivator = PBKDF2KeyDerivator( HMac( SHA1Digest(), 64));
Pbkdf2Parameters params = Pbkdf2Parameters(salt, 12, 32);
derivator.init(params);
return derivator.process(passphrase);
}