FOR ROBUST ONLINE PRIVACY.

In today's climate of zilch online privacy, communicating effectively and secretly has become a dream for individuals as much as for institutions and governments. Everything that is communicated over the Internet today gets copied. Perhaps there are several copies worldwide. This is a problem that bothers Nicolas Gisin, Group Leader, Group of Applied Physics at Geneva University, who has co-founded ID Quantique, a company that manufactures Quantum Key Distribution Systems. He says, "In ten or twenty years, there is no way to guarantee that today's classical cryptographic systems cannot be broken; either by progress in mathematics or classical computer technologies or by quantum computation". He is quick to add, "If we want our exchanges to remain confidential for decades to come, we have to act today...we cannot wait".

While classical key distribution systems rely on the difficulty of factoring large prime numbers for their efficacy, a quantum key distribution relies on the physical properties - namely that when you observe a quantum mechanical system it gets altered completely. So if a quantum state is exchanged between two people, and a third person eavesdrops on the system, they would be destroying the state and thereby bringing it to the notice of the two people that they are being spied on. 

Speaking of the importance of Quantum Key Distribution, Prof. Gisin adds, "So if you want your secrecy to remain confidential for ten, twenty years hence, you have to change your encryption system today. That is a very important thing to understand". A quantum computer may not yet be available for use, but several related products have already made their way into the commercial sector, notably, the Quantum Key Distribution System. Being proven to be secure theoretically makes these systems very exciting. The first company to bring out these systems commercially was ID Quantique, a small company in Geneva, started by academicians in 2001.

The cost of purchasing and maintaining such a system today could be anywhere between 50,000 to a 1,00,000 dollars, according to Prof. Gisin. It is certainly not for the average to use at the moment. The systems use optical fibres to connect the sender and receiver (Alice and Bob as most computation textbooks would use). So far, QKD system has been demonstrated over distances of fifty kilometers. Gisin's team first demonstrated this in a famous experiment across Lake Geneva. Today, they have a line of such products. However, hackers could get around even this apparently fool-proof system. In 2010 and 2011, Vadim Makarov from the Quantum Hacking Lab, Waterloo, Canada, suggested a way of eavesdropping on QKD. This involves temporarily blinding the receiver Bob by shining high intensity light and intercepting the quantum key, and sending a classical communication of the sequence to Bob, who would not detect the difference.

As a counterpoint to this, ID Quantique has come up with introducing random checks. With their work on quantum cryptography being at this stage, the company has also started manufacturing quantum random number generators: Random numbers can be generated very quickly - four mega bits per second. Thus, four million random bits are generated whose randomness is guaranteed by the laws of physics.

C.S. Chakravarthy

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