Quantum Key Distribution Can Improve The Security Of Internet
The security of Internet has many aspects. One key element of Internet's security is cryptography which allows transfer of messages between two parties without allowing third parties to read them. Modern cryptography is based on creation and distribution of keys that are difficult to break with the prevailing techniques and machines. In particular, a key made up of more bits is expected to be more difficult to crack. But a key is always vulnerable to eavesdropping during distribution thus breaking the entire edifice of security.
Concepts of Quantum Mechanics e.g. Uncertainty Principle, Entanglement etc offers a solution to issue. One technique called QKD (Quantum Key Distribution) allows a key to be shared without the risk of being intercepted. There are 2 main implementations of this, one based on Uncertainty principle and the other based on Entanglement. BB84 was the first protocol using the former while E91 was the first protocol using the latter principle. Errors are likely to be introduced in QKD during distribution. Entanglement based protocols are more actively researched than Uncertainty Principle based protocols as they are more efficient for reduction of errors which are introduced during key distribution.
The concept of Entanglement implies that two entangled photons separated from each other still get their properties linked and changes to one are instantaneously transferred to the other despite no visible contact between them. It uses particles, such as photons, to enable two remote parties to produce a shared random secret key known only to them, which can then be used to encrypt and decrypt confidential messages in a classical way. Any attempt to intercept the key during creation and distribution will disturb the correlation, alerting users not to use the key thus preempting eavesdropping.
The biggest challenge at present is to extend the range and increase the data rate of QKD systems and to integrate these systems with existing information security solutions. In optical fibers, this has been achieved over a distance of a few hundred kilometres which restricts their reach to a city or between 2 close by cities. However, in June 2017, China demonstrated entanglement using a special satellite between 2 cities 700 miles apart. The satellite created a pair of entangled particles which were beamed to 2 different ground-based stations. The advantage of using a satellite is that the particles of light travel through space for much of their journey and hence less likely to et disturbed.
QKD is slowly but steadily moving from labs to commercial implementation. The Chinese government has started adopting it. China is also trying to make quantum link over a distance of 2000 km on the ground between Shanghai and Beijing. Various startups are already active in this area and one of them, ID Quantique has actually deployed several QKD networks including one in Soccer World Cup held in South Africa in 2010. Even established companies e.g. Toshiba, Symantec etc. are working on QKD. All this will eventually contribute to the emergence of a quantum internet, where signals would be sent through a quantum network using entangled quantum particles and would be more secure than today's internet.
