Practical quantum key distribution over a 48-km optical fiber network

The secure distribution of the secret random bit sequences known as "key" material, is an essential precursor to their use for the encryption and decryption of confidential communications. Quantum cryptography is a new technique for secure key distribution with single-photon transmissions: Heisenberg's uncertainty principle ensures that an adversary can neither successfully tap the key transmissions, nor evade detection (eavesdropping raises the key error rate above a threshold value). We have developed experimental quantum cryptography systems based on the transmission of non-orthogonal photon states to generate shared key material over multi-kilometer optical fiber paths and over line-of-sight links. In both cases, key material is built up using the transmission of a single-photon per bit of an initial secret random sequence. A quantum-mechanically random subset of this sequence is identified, becoming the key material after a data reconciliation stage with the sender. Here we report the most recent results of our optical fiber experiment in which we have performed quantum key distribution over a 48-km optical fiber network at Los Alamos using photon interference states with the B92 and BB84 quantum key distribution protocols.Comment: 13 pages, 7 figures, .pdf format submitted to Journal of Modern Optic

A Talk on Quantum Cryptography, or How Alice Outwits Eve

Alice and Bob wish to communicate without the archvillainess Eve eavesdropping on their conversation. Alice, decides to take two college courses, one in cryptography, the other in quantum mechanics. During the courses, she discovers she can use what she has just learned to devise a cryptographic communication system that automatically detects whether or not Eve is up to her villainous eavesdropping. Some of the topics discussed are Heisenberg's Uncertainty Principle, the Vernam cipher, the BB84 and B92 cryptographic protocols. The talk ends with a discussion of some of Eve's possible eavesdropping strategies, opaque eavesdropping, translucent eavesdropping, and translucent eavesdropping with entanglement.Comment: 31 pages, 8 figures. Revised version of a paper published in "Coding Theory, and Cryptography: From Geheimscheimschreiber and Enigma to Quantum Theory," (edited by David Joyner), Springer-Verlag, 1999 (pp. 144-174). To be published with the permission of Springer-Verlag in an AMS PSAPM Short Course volume entitled "Quantum Computation.

Study and Design of a Control System for generating and detecting Qubits for the Quantum Exchange of Cryptographic Key

We realized a system for quantum information exchange for cryptographic applications. VHDL describes the hardware for lasers driving and data reception; C++ implements the software for system management. The design is integrated on two boards. A synchronization method guarantees the right timing of the system. The unpredictably of qubit transmission is handled by a suitable time-calibrated receiving windows system. Achieved results improve previous system version in performaces and reliability.ope

Practical quantum cryptography for secure free-space communications

Quantum Cryptography is an emerging technology in which two parties may simultaneously generate shared, secret cryptographic key material using the transmission of quantum states of light. The security of these transmissions is based on the inviolability of the laws of quantum mechanics and information – theoretically secure post- processing methods. An adversary can neither successfully tap the quantum transmissions, nor evade detection, owing to Heisenberg’s uncertainty principle. In this paper we describe the theory of quantum cryptography and the most recent results from our experimental free space system with which we have demonstrated for the first time the feasibility of quantum key generation over a point-to-point outdoor atmospheric path in daylight. We achieved a transmission distance of 0.5km which was limited only by the length of the test range. Our results provide strong evidence that cryptographic key material could be generated on the demand between a ground station and a satellite (or between two satellites), allowing a satellite to be securely re-keyed on orbit. We present a feasibility analysis of surface-to-satellite quantum key generation

Computer science in a multidisciplinary environment : quantum cryptography and econophysics

Students of computer science are becoming increasingly specialized, but to work in multidisciplinary teams they need to appreciate different perspectives and methods. This Final Year Project was carried out in the Physics department at Kochi University of Technology (Japan), and it concerns two interdisciplinary fields: quantum cryptography and econophysics. In the field of quantum cryptography, two of the most representative protocols for quantum key distribution, BB84 and B92, were analyzed and compared; their practical implementation was also described. In the field of econophysics, we explored the properties of the statistical family of Lévy distributions, which are applied in financial computing to model the evolution of prices.Garcés Díaz-Munío, GV. (2009). Computer science in a multidisciplinary environment : quantum cryptography and econophysics. http://hdl.handle.net/10251/14792

Key distribution in PKC through Quantas

Cryptography literally means "The art & science of secret writing & sending a message between two parties in such a way that its contents cannot be understood by someone other than the intended recipient". and Quantum word is related with "Light". Thus, Quantum Cryptography is a way of descripting any information in the form of quantum particles. There are no classical cryptographic systems which are perfectly secure. In contrast to Classical cryptography which depends upon Mathematics, Quantum Cryptography utilizes the concepts of Quantum Physics which provides us the security against the cleverest marauders of the present age. In the view of increasing need of Network and Information Security, we do require methods to overcome the Molecular Computing technologies (A future technology) and other techniques of the various codebrakers. Both the parts i.e. Quantum Key distribution and Information transference from Sender to Receiver are much efficient and secure. It is based upon BB84 protocol. It can be of great use for Govt. agencies such as Banks, Insurance, Brokerages firms, financial institutions, e-commerce and most important is the Defense & security of any country. It is a Cryptographic communication system in which the original users can detect unauthorized eavesdropper and in addition it gives a guarantee of no eavesdropping. It proves to be the ultra secure mode of communication b/w two intended parties.Comment: 11 Pages, JGraph-Hoc Journal 201