Physics

Quantum Privacy

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Science  04 Jul 2008:
Vol. 321, Issue 5885, pp. 17
DOI: 10.1126/science.321.5885.17b

For those that have it and for those that seek it, the saying that information is power is as true today as it ever was. Closely coupled to that, however, is the question of privacy—how to ensure that the information stored in a database is secure (data privacy), and that the information retrieved by users, as in a Web search, is not used against them (user privacy). For good reason, holders of information do not wish to compromise their advantage and so make it difficult to access the information (storing log files). That, however, tends to put users at the disadvantage of having to compromise their privacy or trust the database provider not to use the information in any dishonest way.

Giovannetti et al. show theoretically how quantum mechanics may be able to help ensure privacy for both parties. They have produced a quantum protocol that allows users to access information from a classical database without revealing which item of information it was they retrieved, and also allows perfect data privacy of the database. By quantum mechanically entangling the questions (queries would be addressed as a pulse of entangled photons, for example), any attempt by the database handler to identify which piece of information was retrieved would be scuppered as the user would be alerted. With such a quantum protocol, all parties retain their privacy. — ISO

Phys. Rev. Lett. 100, 230502 (2008).

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