Nono. the master-key never leaves the device. Via the master-key, the program derives(locally) the key to encrypted the data and a different secondary key for

Nono. the master-key never leaves the device. Via the master-key, the program derives(locally) the key to encrypted the data and a different secondary key for authentication against the server. without knowing the master-key you can't decrypt the vault even if you were able to trick the server into sending you the vault. The vault is decrypted locally