  Existing quantum key distribution schemes need the support of classical
authentication scheme to ensure security. This is a conceptual drawback of
quantum cryptography. It is pointed out that quantum cryptosystem does not need
any support of classical cryptosystem to ensure security. No-cloning principal
can alone provide security in communication. Even no-cloning principle itself
can help to authenticate each bit of information. It implies that quantum
password need not to be a secret password.
