“In simple terms, you may say that the main advantage of the protocol is that it allows us to perform a task that, as far as we know, would not be possible to achieve by classical means: that is, it guarantees both user and data privacy without requiring any costly communication and computational overheads, ..."
From the article:
I found it interesting that in describing the interchange between the person looking for information and the repository of that information, the names of Alice and Bob were used. Distracting sort of shortcut (until one gets used to it, I suppose, as with most shortcuts):When an Internet user types a word or phrase into a search engine, the Web server has the ability to find out that inquiry. As more people and businesses are becoming concerned about privacy, researchers are developing new ways to make online activity more secure for both users and servers.
Recently, physicists have created a cheat-sensitive protocol called quantum private queries (QPQ). The quantum-based system allows a user to search for and retrieve an item from a database without revealing that item to the server. If the server tries to find out the item, the user can tell, and modify their use accordingly.
As the physicists explain, the QPQ strategy is designed to protect the user’s privacy and the server’s information. Normally, these two goals are in conflict, since complete privacy for one side means vulnerability for the other. But QPQ takes advantage of elements of quantum theory to provide a compromise.Continue reading: New Quantum Strategy Keeps Web Searches Private
In the QPQ strategy, the user Alice performs a search query, and receives a limited number of answers from the server Bob. If Alice suspects that Bob is trying to figure out her queries, she can perform a search query that is a quantum superposition of different queries. Her answer from Bob will reveal whether the superposition has been altered or not, and she will know if he has been trying to read her queries.
In order for the strategy to work, Alice must send her queries in random order, one at a time. This way, Bob doesn’t know if a query is a normal query or a superposition query intended to detect his attempts at cheating. Sending queries one at a time prevents Bob from making joint measurements, which might go unnoticed.
Although Bob may be lucky and successfully determine one of Alice’s queries by choosing to intercept the normal query instead of the superposition of queries, chances are that he will get caught sooner or later. In fact, the physicists showed that, no matter what sophisticated methods Bob might use to try to intercept Alice’s queries, she will likely discover his attempts.
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