A fiber optic QKD system is developed by using the optical fiber as a standard telecommunications and that QKD system is a short wavelength gigahertz clocked system which is useful for the quantum key distribution along a short distance metropolitan scale networks or metropolitan campus networks. Z.L.Yuan has achieved a quantum key distribution across a constant telecom fiber network of 122km distance. The photon that is entangled is directly distributed to the 7.8 km distanced receiver’s station particularly at night. In the year 2007, a QKD system was executed across an optic fiber network of 25km, this QKD system is a “reverse re-conciliated coherent-state continuous variable system.

A free space system or a QKD system based on entanglement is established over 144km network. Later in the year 2008, an entangled QKD system is established over a links of two free space optical fibers, nearly 1,575 m is separated completely by these links. T. Honjo et al has experimented on the QKD system based on primary entanglement across a 100 km distanced optical fiber network in the year 2008 itself. These White Paper experiments of various researchers have continued for the year 2009 also and in the year 2009, a QKD system based on the entangled state is established between the source and the destination over a network of a distance of 300 km and even in if in a more distanced networks.

All the above experiments of various researchers have proved that the usage of quantum cryptography and quantum communication is precise in real life applications. The fact is that earlier commercial quantum cryptographic device is offered for the application in real time. And so the QKD protocol is presented in the year 2004 along with the analysis of QKA protocol and its efficiency. In Quantum cryptography, most important and technical support is achieved by the quantum key distribution. QKD can be considered as the advanced tool for the cryptographers for making a secure key agreement using an un-trusted channel, which means QKD permits an channel that is un-trusted to make a secure key agreement. In quantum cryptography White Paper Presentation, the out is dependent on the input in using QKD and this is not possible in traditional cryptography. QKD is used build the systems using the designed security properties and so the additional cryptographic primitives like authentication are also existed in the system.

The additional primitives that are existed in quantum cryptography are quantum money, blind quantum computation, quantum coin tossing and quantum public key encryption; these primitives are designed by using the medium-to-large quantum computer. Many research groups has researched on the QKD systems and the implementations are done and considered as complex economically and so the usage of QKD will be high in the future security infrastructures.

This Paper is written & submitted by **Vamshidhar A.**