Industrial Feasibility of Private Information Retrieval

A popular security problem in database management is how to guarantee to a querying party that the database owner will not learn anything about the data that is retrieved — a problem known as Private Information Retrieval (PIR). While a variety of PIR schemes are known, they are rarely considered for practical use cases yet. We investigate the feasibility of PIR in the telecommunications world to open up data of carriers to external parties. To this end, we first provide a comparative survey of the current PIR state of the art (including ORAM schemes as a generalized concept) as well as implementation and analysis of two PIR schemes for the considered use case. While an overall conclusion is that PIR techniques are not too far away from practical use in specific cases, we see ORAM as a more suitable candidate for further R&D investment. 1 Background and Motivation The telecommunications world is undergoing a transition where carriers not only provide services such as telephony or internet access, but also attempt to monetize the huge amount of data associated with their subscribers’ activity. Analyzing data such as call statistics or roaming behavior can be used to offer specifically tailored services and packages. The combination of such data with other data from 3 parties can potentially result in even more value. As such, one direction is to open up the existing databases to subscribing external parties. In fact, it may very well be the case that two rivaling carriers allow each other to query their subscriber databases, e.g. for detecting faults in the network or to support detection of fraudulent activities. Another real-world scenario is that of answering to the demands of public authorities which may want to verify that a user has been making a call at a certain time or to assess whether a certain IMEI or IMSI is part of the carriers subscriber base. An open practical problem is how to guarantee to the querying party that the database owner will not learn anything about the data that is retrieved — a problem known as Private Information Retrieval (PIR) [8]. Accordingly, we assessed the feasibility of PIR schemes to support such use cases, where the typical database consists of 400.000-800.000 entries of IMEIs and/or IMSIs. This paper provides a comparative survey of PIR schemes as part of Section 2. We