| Author | Günther, Daniel; Schneider, Thomas; Wiegand, Felix |
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| Date | 2021 |
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| Type | Conference Proceedings |
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| Abstract | Private Information Retrieval (PIR) allows a client to request entries from a public database held by k servers without revealing any information about the requested data to the servers. PIR is classified into two classes: (i) Multi-server PIR protocols where the request is split among k≥2 non-colluding servers, and Single-server PIR protocols where exactly k=1 server holds the database while the query is protected via certain computational hardness assumptions.
Devet & Goldberg (PETS'14) showed that both can be combined into one recursive PIR protocol in order to improve the communication complexity. Their hybrid PIR protocol is instantiated with the multi-server PIR protocol of Goldberg (S&P'07) and the single-server PIR protocol by Melchar & Gaborit (WEWoRC'07), resulting in online request runtime speedups and guaranteeing at least partial privacy if the multi-server PIR servers do in fact collude.
In this work we show that the hybrid PIR protocol by Devet & Goldberg still has practical relevance by designing a hybrid approach using the state-of-the-art multi-server protocol CIP-PIR (Günther et al., ePrint'21/823) and the single-server protocol SealPIR (Angel et al., S&P'18). Our novel hybrid PIR protocol massively improves the linear communication complexity of CIP-PIR and obtains the strong property of client-independent preprocessing, which allow batch-preprocessing among multiple clients without the clients being involved. We implement and benchmark our protocol and get speedups of ≈4.36× over the original implementation of Devet & Goldberg (8 GiB DB), speedups of ≈26.08× (8 GiB DB) over CIP-PIR, and speedups of ≈11.16× over SealPIR (1 GiB DB). |
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| Conference | 27th ACM SIGSAC Conference on Computer and Communications Security |
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| Isbn | 978-1-4503-8454-4 |
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| In | CCS '21: Proceedings of the 2021 ACM SIGSAC Conference on Computer and Communications Security, p.2408-2410 |
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| Publisher | ACM |
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| Url | https://tubiblio.ulb.tu-darmstadt.de/id/eprint/132914 |
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