openFile method
Implementation
Future<UAead> openFile(UVaultHeader header) async {
final Uint8List fileKey = await _master.open(Uint8List.sublistView(header.wrappedKey, 0, 12), Uint8List.sublistView(header.wrappedKey, 12));
final UAead aead = await _backend.aead(fileKey);
if (aead.algorithmId != header.algorithmId) throw const FormatException("Vault file was written by a different platform cipher.");
return aead;
}