{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,28]],"date-time":"2026-05-28T21:03:39Z","timestamp":1780002219146,"version":"3.53.1"},"reference-count":0,"publisher":"Privacy Enhancing Technologies Symposium Advisory Board","issue":"2","license":[{"start":{"date-parts":[[2026,4,1]],"date-time":"2026-04-01T00:00:00Z","timestamp":1775001600000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["PoPETs"],"abstract":"<jats:p>Private information retrieval (PIR) allows a client to query a public database privately and serves as a key building block for privacy-enhancing applications. Minimizing query size is particularly important in many use cases, for example, when clients operate on bandwidth-constrained devices. However, existing PIR protocols exhibit large query sizes: to query 225 records, the smallest query size of 14.8 KB is reported in Respire [Burton et al., CCS24]. Respire is based on fully homomorphic encryption (FHE), where a common approach to lower the client-to-server communication cost is transciphering. When combining the state-of-the-art transciphering [Bon et al., CHES24] with Respire, the resulting protocol (which we refer to as T-Respire) has a 336 B query size, while incurring a 16.2x times higher server computation cost than Respire. Our work introduces a novel alternative to transciphering for reducing the client-to-server communication: the client transmits only one component of a high-precision LWE ciphertext, from which we design a modular procedure to extract the inputs for the subsequent homomorphic computation. The efficiency of this approach is demonstrated by our Pirouette protocol, which achieves a query size of just 36 B. This represents a 9.3x reduction compared to T-Respire and a 420x reduction to Respire. For queries over 225 records, the single-core server computation in Pirouette is only 2x slower than Respire and 8.1x faster than T-Respire, and the server computation is highly parallelizable. Furthermore, Pirouette requires no database-specific hint for clients, and its variant PirouetteH enables additional tradeoffs among query size, throughput, and offline communication, demonstrating the flexibility of our design<\/jats:p>","DOI":"10.56553\/popets-2026-0045","type":"journal-article","created":{"date-parts":[[2026,5,22]],"date-time":"2026-05-22T23:10:41Z","timestamp":1779491441000},"page":"215-241","source":"Crossref","is-referenced-by-count":0,"title":["Pirouette: Query Efficient Single-Server PIR"],"prefix":"10.56553","volume":"2026","author":[{"given":"Jiayi","family":"Kang","sequence":"first","affiliation":[{"name":"COSIC, KU Leuven"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Leonard","family":"Schild","sequence":"additional","affiliation":[{"name":"COSIC, KU Leuven"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"35752","published-online":{"date-parts":[[2026,4]]},"container-title":["Proceedings on Privacy Enhancing Technologies"],"original-title":[],"deposited":{"date-parts":[[2026,5,28]],"date-time":"2026-05-28T20:21:13Z","timestamp":1779999673000},"score":1,"resource":{"primary":{"URL":"https:\/\/petsymposium.org\/popets\/2026\/popets-2026-0045.php"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,4]]},"references-count":0,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2026,4]]}},"alternative-id":["10.56553\/popets-2026-0045"],"URL":"https:\/\/doi.org\/10.56553\/popets-2026-0045","relation":{},"ISSN":["2299-0984"],"issn-type":[{"value":"2299-0984","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,4]]}}}