Strong attacks against quantum key distribution use quantum memories and quantum gates to attack directly the final key. In this paper we extend a novel security result recently obtained, to demonstrate proofs of security against a wide class of such attacks. To reach this goal we calculate information-dependent reduced density matrices, we study the geometry of quantum mixed states, and we find bounds on the information leaked to an eavesdropper. Our result suggests that quantum cryptography is ultimately secure.
The extend success of any communication system essentially depends on the strength of the secrecy of transporting the information between the partners.The classical cryptography for the wired and wireless communication systems can not withstand against the challenges of new technologies.So, it is necessary to invent a new method to encrypt the information.The solution is quantum cryptography in communication system.The absolute security can be achieve with quantum cryptography protocol via building an effective hardware for satisfying the single-photon source must requirement by controlling the value of mean photon number.This was approximately achieved in this work by building a driving circuit that provide very short pulses, less than 10 ns for Laser Diode with output maximum power of 0.99 mW and wavelength 650 nm.These short pulses enable getting faint laser pulses that were further attenuated to reach mean photon number equal to 0.08 or less.
Computer center The extend success of any communication system essentially depends on the strength of the secrecy of transporting the information between the partners. The classical cryptography for the wired and wireless communication systems can not withstand against the challenges of new technologies. So, it is necessary to invent a new method to encrypt the information. The solution is quantum cryptography in communication system. The absolute security can be achieve with quantum cryptography protocol via building an effective hardware for satisfying the single-photon source must requirement by controlling the value of mean photon number. This was approximately achieved in this work by building a driving circuit that provide very short pulses, less than 10 ns for Laser Diode with output maximum power of 0.99 mW and wavelength 650 nm. These short pulses enable getting faint laser pulses that were further attenuated to reach mean photon number equal to 0.08 or less.