Editing (Symmetric) Private Information Retrieval (section)

==Description==
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Private information retrieval (PIR) is a classical cryptographic functionality that allows one party (user) to privately retrieve an element from a classical database owned by another party (server), i.e., without revealing to the other party which element is being retrieved (user privacy).<br></br>
Symmetric private information (SPIR) retrieval is PIR with the additional requirement that throughout and after the protocol, the user remains oblivious to other database elements, i.e., apart from the queried one (data privacy).<br></br>
In the quantum setting, the use of quantum systems is allowed to achieve (S)PIR: this may imply the use of a quantum channel between the user and the server, and the capability to prepare quantum states, apply quantum gates or measure quantum systems by one or both parties. (S)PIR in this setting is known as quantum (symmetric) private information retrieval (Q(S)PIR).<br></br>
In the classical or quantum setting, (Q)SPIR and one-out-of-n (quantum) [[Oblivious Transfer|oblivious transfer]] (OT) are similar cryptographic tasks; the only minor difference between those functionalities is that protocols for OT are two-party protocols, while attempts at achieving SPIR have considered both two-party and multi-party protocols where the user communicates with several servers, each holding a copy of the database.<br></br>
Apart from using quantum techniques to enhance the classical (S)PIR functionality (i.e., design better protocols than their classical counterparts in terms of different metrics like e.g., communication complexity), there has also been a recent interest in a ‘fully’ quantum (S)PIR where a user wants to query a quantum database (items are quantum states)[[#References|[1]]].<br></br>

'''Tags:''' 
[[:Category:Two Party Protocols|Two Party Protocol]],[[Category:Two Party Protocols]] 
[[:Category:Specific Task|Specific Task]], [[Category:Specific Task]] 
[[:Category: Quantum Enhanced Classical Functionality|Quantum Enhanced Classical Functionality]].[[Category:Quantum Enhanced Classical Functionality]]

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