buildKey function
Implementation
Key buildKey(String masterPassword) {
// use masterPassword to generate Key
// convert masterPassword into md5 hash
// convert md5 hash into 32 bytes
final mp = md5.convert(utf8.encode(masterPassword)).bytes;
final mp32 = mp.sublist(0, 16) + mp.sublist(0, 16).reversed.toList();
final b64 = base64.encode(mp32);
return encrypt.Key.fromBase64(b64);
}