Quantum cryptography (or QKD) offers an automated procedure for distributing secret keys utilizing generally used communication fibres. The revolutionary characteristic of Q KD is that it is intrinsically secure: the key
cannot be acquired by an eavesdropper without the sender and addressee's knowledge. Moreover, QKD permits the key to be changed often.The philosophical meaning if quantum cryptography consists of
existing an absolute secure communication which guarantees on private inviolability from Big Brother's infringement.