TOKYO, September 26, 2000--Mitsubishi Electric Corporation (President and CEO: Ichiro Taniguchi) and the Research Institute for Electronic Science, Hokkaido University (Associate Professor: Shigeki Takeuchi) announced today the success of their quantum cryptographic experimental system. This is the first report in Japan concerning quantum cryptosystem experiments for absolute security against cryptanalysis.

This experiment, which used optical fibers, has great significance for applicability to installed optical fiber networks.

Background and Abstract

The security of almost all of modern cryptography is evaluated on the basis of computational complexity. Cryptanalysis requires extraordinary complexity or time. Therefore, modern cryptography has two critical defects: one is that it could be breakable by the advent of high-performance computers like quantum computers and the other is that it cannot detect eavesdroppers. Therefore, there are demands for "absolutely secure cryptography that cannot be broken."

Quantum cryptography is based on the fundamental physical law that observation by eavesdroppers inevitably affects the quantum system and the information of the system before observation, making the information incomplete. That is, once communication content is tapped on the channel, the content itself changes irreversibly. The eavesdropped content, then, becomes meaningless and the legitimate recipient can detect the eavesdropper by the change in content. Thus the legitimate initiator and recipient are able to take measures against eavesdropping.

The first experiment in quantum cryptography was reported in the U.S. in 1989. It was practiced between 30cm via free space. Until now, some experiments using optical fiber have also been practiced in the U.S. and Europe. In Japan, however, such experiments almost have not been reported yet.

Mitsubishi has already developed linear cryptanalysis, the block cipher MISTY, which has provable security, and public key cryptosystems such as elliptic curve cryptography.

Recently KASUMI, based on the design of MISTY, has been adopted as the global standard algorithm for use in next-generation cellular phones (W-CDMA). Mitsubishi Electric is therefore in a dominant position in the information security and cryptography field.

In addition to these modern cryptographic technologies, Mitsubishi Electric has focused on quantum cryptography and, as a result, successfully realized quantum cryptographic communication systems as a security system. This technology provides us with absolutely secure communication channels.

Mitsubishi Electric will take the next step and apply quantum cryptography to installed fibers for general telecommunication use and make the bit rate (transmission speed) higher.

Results & Specifications

1. First successful experiment in Japan in quantum cryptography for communication systems

Basic features:
• Key distribution
• Detection of eavesdroppers


Data processing functions as a quantum cryptographic communication system:

• Error correcting, privacy amplification

• Bit rate: 1kbps
• Quantum bit error rate:  1%
• Transmission distance:  200m (optical fiber)
• Optical system which can compensate for fluctuation of phase and polarization

About Mitsubishi Electric Corporation

With more than 75 years of experience in providing reliable, high-quality products to both corporate clients and general consumers all over the world, Mitsubishi Electric Corporation (FTSE: 6503q.l) is a recognized world leader in the manufacture, marketing and sales of electrical and electronic equipment used in information processing and communications, space development and satellite communications, consumer electronics, industrial technology, energy, transportation and construction. With operations in 36 countries, Mitsubishi Electric Corporation recorded consolidated group sales of over US$35 billion in the year ended March 31, 2000. Additional information on Mitsubishi Electric Corporation is available at global.mitsubishielectric.com.