{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,11,6]],"date-time":"2026-11-06T06:21:49Z","timestamp":1793946109815,"version":"4.8.0"},"reference-count":18,"publisher":"Springer Science and Business Media LLC","issue":"1","license":[{"start":{"date-parts":[[2026,6,8]],"date-time":"2026-06-08T00:00:00Z","timestamp":1780876800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"},{"start":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T00:00:00Z","timestamp":1791417600000},"content-version":"vor","delay-in-days":122,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"}],"funder":[{"DOI":"10.13039\/501100005416","name":"Norges Forskningsr\u00e5d","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100005416","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["link.springer.com"],"crossmark-restriction":false},"short-container-title":["npj Digit. Med."],"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>\n                    The proliferation of real-world health data enables multi-institutional survival studies, yet privacy constraints preclude centralizing sensitive records. We present a privacy-preserving federated Kaplan\u2013Meier framework based on threshold CKKS (Cheon-Kim-Kim-Song) homomorphic encryption that supports approximate floating-point computation and encrypted aggregation of per-time-point counts while exposing only public outputs. Sites compute aligned at-risk and event tallies on a shared time grid and encrypt compact vectors; a coordinator aggregates ciphertexts; and a decryptor committee produces partial shares fused per block to recover aggregated plaintexts without releasing per-time-point tables. We prove correctness, stability, and slot-optimal vector packing, and derive scaling laws showing that communication grows linearly with the number of sites and predictably with the number of time points. Empirically, using synthetic breast-cancer data (\n                    <jats:italic>N<\/jats:italic>\n                    \u2009=\u200960,000) distributed across 500 sites, encrypted federated curves match the pooled oracle to numerical precision. In contrast, plaintext protocols permit trivial reconstruction by subtraction; our threshold-gated design precludes this attack under the stated threat model, enabling high-fidelity survival estimation with predictable overhead and substantially reduced privacy risk.\n                  <\/jats:p>","DOI":"10.1038\/s41746-026-02790-4","type":"journal-article","created":{"date-parts":[[2026,6,8]],"date-time":"2026-06-08T14:36:13Z","timestamp":1780929373000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["A multiparty homomorphic encryption approach to confidential federated Kaplan\u2013Meier survival analysis"],"prefix":"10.1038","volume":"9","author":[{"given":"Narasimha Raghavan","family":"Veeraragavan","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Svetlana","family":"Boudko","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jan Franz","family":"Nyg\u00e5rd","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2026,6,8]]},"reference":[{"key":"2790_CR1","doi-asserted-by":"publisher","DOI":"10.1038\/s41467-021-25972-y","volume":"12","author":"D Froelicher","year":"2021","unstructured":"Froelicher, D. et al. Truly privacy-preserving federated analytics for precision medicine with multiparty homomorphic encryption. Nat. Commun. 12, 5910 (2021).","journal-title":"Nat. Commun."},{"key":"2790_CR2","doi-asserted-by":"publisher","first-page":"e2304415120","DOI":"10.1073\/pnas.2304415120","volume":"120","author":"R Geva","year":"2023","unstructured":"Geva, R. et al. Collaborative privacy-preserving analysis of oncological data using multiparty homomorphic encryption. Proc. Natl. Acad. Sci. USA. 120, e2304415120 (2023).","journal-title":"Proc. Natl. Acad. Sci. USA."},{"key":"2790_CR3","doi-asserted-by":"crossref","unstructured":"Rahimian, S., Kerkouche, R., Kurth, I. & Fritz, M. Private and collaborative Kaplan\u2013Meier estimators. In Proc. 23rd Workshop on Privacy in the Electronic Society (WPES \u201924) (eds Ayday, E. & Vaidya, J) 212\u2013241 (Association for Computing Machinery, 2024).","DOI":"10.1145\/3689943.3695039"},{"key":"2790_CR4","unstructured":"Veeraragavan, N. R. & Nyg\u00e5rd, J. F. Federated survival analysis with node-level differential privacy: private Kaplan\u2013Meier curves. Preprint at https:\/\/arxiv.org\/abs\/2509.00615 (2025)."},{"key":"2790_CR5","doi-asserted-by":"crossref","unstructured":"von Maltitz, M. et al. A privacy-preserving log-rank test for the Kaplan\u2013Meier estimator with secure multiparty computation: algorithm development and validation. JMIR Med. Inform. 9, https:\/\/www.sciencedirect.com\/science\/article\/pii\/S2291969421000326 (2021).","DOI":"10.2196\/22158"},{"key":"2790_CR6","doi-asserted-by":"crossref","unstructured":"Cheon, J. H., Kim, A., Kim, M. & Song, Y. Homomorphic encryption for arithmetic of approximate numbers. in Advances in Cryptology\u2014ASIACRYPT 2017 (eds Takagi, T. & Peyrin, T.), 409\u2013437 (Springer International Publishing, 2017).","DOI":"10.1007\/978-3-319-70694-8_15"},{"key":"2790_CR7","doi-asserted-by":"publisher","first-page":"e22158","DOI":"10.2196\/22158","volume":"9","author":"M von Maltitz","year":"2021","unstructured":"von Maltitz, M. et al. A privacy-preserving log-rank test for the Kaplan-Meier estimator with secure multiparty computation: algorithm development and validation. JMIR Med. Inform. 9, e22158 (2021).","journal-title":"JMIR Med. Inform."},{"key":"2790_CR8","doi-asserted-by":"publisher","first-page":"70","DOI":"10.1561\/3300000019","volume":"2","author":"D Evans","year":"2018","unstructured":"Evans, D., Kolesnikov, V. & Rosulek, M. A pragmatic introduction to secure multi-party computation. Found. Trends\u00ae Priv. Secur. 2, 70\u2013246 (2018).","journal-title":"Found. Trends\u00ae Priv. Secur."},{"key":"2790_CR9","doi-asserted-by":"crossref","unstructured":"Li, B. & Micciancio, D. On the security of homomorphic encryption on approximate numbers. in Advances in Cryptology \u2013 EUROCRYPT 2021 Vol. 12696 of Lecture Notes in Computer Science (eds Canteaut, A. & Standaert, F.-X.) 648\u2013677 (Springer, 2021).","DOI":"10.1007\/978-3-030-77870-5_23"},{"key":"2790_CR10","doi-asserted-by":"crossref","unstructured":"Asharov, G. et al. Multiparty computation with low communication, computation and interaction via threshold FHE. In Advances in Cryptology\u2014EUROCRYPT 2012 (eds Pointcheval, D. & Johansson, T.) 483\u2013501 (Springer Berlin Heidelberg, 2012).","DOI":"10.1007\/978-3-642-29011-4_29"},{"key":"2790_CR11","doi-asserted-by":"crossref","unstructured":"Cramer, R., Damg\u00e5rd, I. B. & Nielsen, J. B. Secure Multiparty Computation and Secret Sharing (Cambridge University Press, 2015).","DOI":"10.1017\/CBO9781107337756"},{"key":"2790_CR12","unstructured":"Badawi, A. A. et al. OpenFHE: Open-source fully homomorphic encryption library. Cryptology ePrint Archive, Paper 2022\/915. Accessed 01 October 2024. https:\/\/eprint.iacr.org\/2022\/915 (2022)."},{"key":"2790_CR13","unstructured":"Fan, J. & Vercauteren, F. Somewhat practical fully homomorphic encryption. Cryptology ePrint Archive, Paper 2012\/144. Accessed 01 October 2024. https:\/\/eprint.iacr.org\/2012\/144 (2012)."},{"key":"2790_CR14","doi-asserted-by":"crossref","unstructured":"Brakerski, Z. Fully homomorphic encryption without modulus switching from classical gapsvp. In Advances in Cryptology\u2014CRYPTO 2012 (eds Safavi Naini, R. & Canetti, R.) 868\u2013886 (Springer Berlin Heidelberg, 2012).","DOI":"10.1007\/978-3-642-32009-5_50"},{"key":"2790_CR15","doi-asserted-by":"crossref","unstructured":"Brakerski, Z., Gentry, C. & Vaikuntanathan, V. (Leveled) fully homomorphic encryption without bootstrapping. In Proc. 3rd Innovations in Theoretical Computer Science Conference (ITCS \u201912) (ed. Goldwasser, S.) 309\u2013325 (Association for Computing Machinery, New York, NY, USA, 2012).","DOI":"10.1145\/2090236.2090262"},{"key":"2790_CR16","doi-asserted-by":"crossref","unstructured":"Ducas, L. & Micciancio, D. Fhew: Bootstrapping homomorphic encryption in less than a second. In Advances in Cryptology\u2014EUROCRYPT 2015 (eds Oswald, E. & Fischlin, M.) 617\u2013640 (Springer Berlin Heidelberg, 2015).","DOI":"10.1007\/978-3-662-46800-5_24"},{"key":"2790_CR17","unstructured":"Chillotti, I., Gama, N., Georgieva, M. & Izabach\u00e8ne, M. TFHE: Fast fully homomorphic encryption over the torus. Cryptology ePrint Archive, Paper 2018\/421 (2018). https:\/\/eprint.iacr.org\/2018\/421."},{"key":"2790_CR18","doi-asserted-by":"crossref","unstructured":"Chillotti, I., Gama, N., Georgieva, M. & Izabach\u00e8ne, M. Faster fully homomorphic encryption: bootstrapping in less than 0.1 seconds. In Advances in Cryptology\u2014ASIACRYPT 2016 (eds Cheon, J. H. & Takagi, T.) 3\u201333 (Springer Berlin Heidelberg, 2016).","DOI":"10.1007\/978-3-662-53887-6_1"}],"container-title":["npj Digital Medicine"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.nature.com\/articles\/s41746-026-02790-4","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/www.nature.com\/articles\/s41746-026-02790-4.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/www.nature.com\/articles\/s41746-026-02790-4.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,10,7]],"date-time":"2026-10-07T23:10:37Z","timestamp":1791414637000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.nature.com\/articles\/s41746-026-02790-4"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,6,8]]},"references-count":18,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2026,12]]}},"alternative-id":["2790"],"URL":"https:\/\/doi.org\/10.1038\/s41746-026-02790-4","relation":{"has-preprint":[{"id-type":"doi","id":"10.21203\/rs.3.rs-6496298\/v1","asserted-by":"object"}]},"ISSN":["2398-6352"],"issn-type":[{"value":"2398-6352","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,6,8]]},"assertion":[{"value":"21 April 2025","order":1,"name":"received","label":"Received","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"14 May 2026","order":2,"name":"accepted","label":"Accepted","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"8 June 2026","order":3,"name":"first_online","label":"First Online","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"The authors declare no competing interests.","order":1,"name":"Ethics","label":"Competing interests","group":{"name":"EthicsHeading","label":"Ethics"}}],"article-number":"775"}}