Enhancing security in quantum cryptography

Quantum Key Distribution was named as one of the top ten emerging technologies by Technology Review Journal in 2003 in their annual edition. The growth in quantum cryptography since the beginning of the millennium has been expedited by new theories and ideas. The introduction of practical quantum cryptosystems offered by USA based company MagiQTech and its European rival idQuantique has changed the face of cryptography. With active experimental research in USA, Europe, Japan and Singapore, the scope of quantum cryptography seems to be growing daily. When Bennett and Brassard proposed their BB84 protocol in Bangalore in 1984, no one would have guessed the quantum revolution they had launched. Since then, new protocols have been proposed and new theories developed, but BB84 remains the simplest and probably the easiest to implement. Now that the practical implementation of basic quantum cryptography has been achieved, one can be almost certain that new protocols will sooner or later be tested for the efficiency they could provide. We have developed a Classical Authentication Aided (CAA) protocol, which merges the classical authentication policies with quantum transmission to make it even more secure. With the complexities of the authentication policies and the bit to qubit conversion, our system becomes a complex one. We also discuss the possibilities of free space quantum transmission of the protocol instead of only through optical fiber

Methods to Counter Attacks on Quantum Cryptography Protocols

The need for secure transmission in the fields of banking and defense has led to the interest in quantum cryptographic protocols which are theoretically more secure than any classical cryptographic protocol. However, the current implementations of the quantum cryptographic protocols have weaknesses. The main goal of this work is to find ways to strengthen quantum cryptographic protocols by using new implementation schemes. We present a method to improve the randomness of the sequence of polarization states used in BB84, the two-stage and the three-stage protocols. An analysis of quantum cryptography in the presence of noise is given. We also study a variant of the three-stage protocol where the intensity of the photons is tracked. We have developed a further improvement to this protocol where the state of the photons is also estimated.Computer Scienc

Fast Convergent and Secure Key Distribution Protocols Using a Dual-Quantum Channel

This dissertation presents three new quantum key distribution protocols over a dual quantum-channel to enhance the convergence speed of the key distribution process. The proposed protocols effectively use a dual-quantum channel between the communicating entities and, when combined with the proposed selection of the basis, improve the efficiency of the key distribution process as well as deter Eve. With the use of an initialization vector, one of the proposed protocols does not necessitate information exchange about the bases between Alice and Bob, and further eliminates the requirement of the availability of a two-way conventional channel. Simultaneously, it allows the detection of the presence of Eve in real time and proposes several effective defense mechanisms to frustrate Eve's attack