From Quantum Cheating to Quantum Security

Hoi-Kwong Lo, University of Toronto, Canada

The contest between code-makers and code-breakers has been going on for thousands of years. Recently quantum mechanics has made a remarkable entry in the subject. On one hand, quantum computing can break standard encryption schemes, thus threatening the very foundation of data security. On the other hand, quantum cryptography can come to the rescue by allowing perfectly secure communication guaranteed by the laws of physics. However, some cryptographic tasks such as bit commitment have been shown to be fundamentally impossible, even with the help of quantum mechanics. Here, I survey the power and limitation of quantum cryptography. I also remark that quantum cryptographic products are currently available in the commercial market.

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