No-cloning principal can alone provide security
  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. 
Arindam Mitra