Cryptology ePrint Archive: Report 1998/016

Quantum Computers Render Quantum Key Distribution Unconditionally Secure Over Arbitrarily Long Distances

Hoi-Kwong Lo and H. F. Chau

Abstract: Abstract: Quantum cryptography has long been claimed to be useful for achieving many tasks that are impossible from the perspective of conventional cryptography. Arguably, the most important problem in quantum cryptography has been a rigorous proof of the security of quantum key distribution, the most well-known application. This notoriously hard problem has eluded researchers for years and has become even more important after the recent surprising demonstration of the insecurity of many other quantum cryptographic schemes including quantum bit commitment. Here, we solve this long standing problem by showing that, given quantum computers, quantum key distribution over an arbitrarily long distance of a realistic noisy channel can be made unconditionally secure. The novel technique we use is reduction from a quantum scheme to a classical scheme. The security in realistic noisy environments is then proven by using the recent theory of fault-tolerant quantum computation.

Category / Keywords: Quantum key distribution, quantum cryptography, key-distribution problems, unconditional security.

Publication Info: Appeared in the THEORY OF CRYPTOGRAPHY LIBRARY and has been included in the ePrint Archive. This paper was removed from the library in January 1999 at the authors' request due to copyright issues.

Date: received May 22, 1998, withdrawn January 1999

Contact author: hkl at hplb hpl hp com

Available format(s): (-- withdrawn --)

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