Time-polarization coding in quantum cryptography

We present a quantum key distribution (QKD) method that allows us to demonstrate practical quantum cryptography. It is used for obtaining the cryptographic key to encode the information communicated between to legitimate parties. It generally relates to a secured key sharing method and system between a plurality of transmitters and a plurality of receivers, more particularly to a system and method of QKD between transmitters and receivers. The aspect of the method is a QKD system capable of forming the first signals with different phases or polarization and the second signals with different delay time. The transmitter sends the two signals to share the key with receiver. The first signal is generated in different phases or polarization to protect the transmission channel and to be the reference time for second signal. The state of first signal and the delay time between the first signal and second signal is the key. The method leads to increase the length of the shared key. This method is used to implement the practical QKD system that can be used for switching between our protocol and BB84 protocol in optical fiber (one-way system) and free space setups with unconditionally security. Secure keys generated by the QKD network are managed in the key management layer by key management agents (KMAs), and used to encrypt the data and send it to receivers. The proposed schemes aimed to provide a secure end to end communication.