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Existing privacy protection strategies predominantly rely on source-side solutions, such as hardware modifications to encrypt wireless channels. While partially effective, these approaches often necessitate costly and impractical hardware upgrades and, in some cases, fail to accommodate the needs of authorized users, thereby compromising their sensing performance in practical scenarios. To overcome these limitations, we propose MetAegis, an innovative channel-side obfuscation system that leverages a programmable metasurface for flexible and cost-effective deployment. MetAegis dynamically alters the wireless channel to achieve selective feature obfuscation across multiple directions, effectively shielding against malicious users while ensuring that authorized users experience no degradation in performance. This is accomplished through a feature obfuscation technique driven by switching coding configurations on the metasurface, coupled with a feature recovery framework that enables authorized users to accurately reconstruct activity-related features from obfuscated signals. We implemented MetAegis using off-the-shelf Wi-Fi devices and conducted extensive evaluations across three real-world scenarios. Experimental results demonstrate that MetAegis reduces eavesdropper recognition accuracy to below 24% on average, while authorized users maintain average accuracy exceeding 88% through the recovery mechanism under the regular deployment. Remarkably, unlike traditional source-side solutions that require close integration with transmitters, MetAegis sustains its effectiveness even under challenging conditions, such as when the metasurface is positioned over 5 meters from the transmitter. These findings underscore the practicality and robustness of MetAegis in safeguarding privacy without sacrificing usability.<\/jats:p>","DOI":"10.1145\/3790113","type":"journal-article","created":{"date-parts":[[2026,3,16]],"date-time":"2026-03-16T17:51:14Z","timestamp":1773683474000},"page":"1-28","update-policy":"https:\/\/doi.org\/10.1145\/crossmark-policy","source":"Crossref","is-referenced-by-count":1,"title":["MetAegis: Defend Against Physical-layer Wireless Sensing Leakage via Metasurface Obfuscation"],"prefix":"10.1145","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0009-0003-7485-1713","authenticated-orcid":false,"given":"Jinjiang","family":"Yang","sequence":"first","affiliation":[{"name":"Northwest University, Xi'an, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0869-7266","authenticated-orcid":false,"given":"Chenghan","family":"Jiang","sequence":"additional","affiliation":[{"name":"Northwest University, Xi'an, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9176-170X","authenticated-orcid":false,"given":"Jie","family":"Zhang","sequence":"additional","affiliation":[{"name":"Xi'an University of Posts and Telecommunications, Xi'an, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9702-3417","authenticated-orcid":false,"given":"Xinyi","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Computer Science and Software, Northwest University, Xi'an, Shannxi, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0005-8475-7880","authenticated-orcid":false,"given":"Boxuan","family":"Yang","sequence":"additional","affiliation":[{"name":"Northwest University, Xi'an, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-2023-118X","authenticated-orcid":false,"given":"Shibo","family":"Zhang","sequence":"additional","affiliation":[{"name":"Northwest University, Xi'an, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4485-457X","authenticated-orcid":false,"given":"Xianjia","family":"Meng","sequence":"additional","affiliation":[{"name":"Northwest University, Xi'an, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-9717-1377","authenticated-orcid":false,"given":"Zhuzhu","family":"Wang","sequence":"additional","affiliation":[{"name":"Northwest University, Xi'an, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5816-6922","authenticated-orcid":false,"given":"Dingyi","family":"Fang","sequence":"additional","affiliation":[{"name":"Northwest University, Xi'an, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4333-2334","authenticated-orcid":false,"given":"Zhanyong","family":"Tang","sequence":"additional","affiliation":[{"name":"Northwest University, Xi'an, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"320","published-online":{"date-parts":[[2026,3,16]]},"reference":[{"key":"e_1_2_1_1_1","unstructured":"[n.d.]. Burglaries. https:\/\/www.covesmart.com\/blog\/10-signs-burglars-are-casing-a-house\/ ."},{"key":"e_1_2_1_2_1","unstructured":"[n.d.]. CareClaim. https:\/\/www.accidentclaimsadvice.org.uk\/care-home-negligence-claims\/."},{"key":"e_1_2_1_3_1","unstructured":"[n.d.]. CSI tool. https:\/\/dhalperi.github.io\/linux-80211n-csitool\/ ."},{"key":"e_1_2_1_4_1","unstructured":"[n.d.]. ESP32. https:\/\/stevenmhernandez.github.io\/ESP32-CSI-Tool\/ ."},{"key":"e_1_2_1_5_1","unstructured":"[n. d.]. Home carer stole from elderly. https:\/\/www.bbc.com\/news\/uk-england-kent-19946587 ."},{"key":"e_1_2_1_6_1","unstructured":"[n. d.]. iperf3 network tool. http:\/\/software.es.net\/iperf ."},{"key":"e_1_2_1_7_1","unstructured":"[n. d.]. SMP1340-040LF. https:\/\/www.skyworksinc.com\/Products\/ Diodes\/SMP1340-Series. ."},{"key":"e_1_2_1_8_1","doi-asserted-by":"publisher","DOI":"10.1145\/2746285.2755969"},{"key":"e_1_2_1_9_1","doi-asserted-by":"publisher","DOI":"10.1109\/JIOT.2022.3177410"},{"key":"e_1_2_1_10_1","doi-asserted-by":"publisher","DOI":"10.1109\/ICC51166.2024.10622873"},{"key":"e_1_2_1_11_1","doi-asserted-by":"publisher","DOI":"10.1109\/JIOT.2022.3181592"},{"key":"e_1_2_1_12_1","unstructured":"Alexey Dosovitskiy Lucas Beyer Alexander Kolesnikov Dirk Weissenborn Xiaohua Zhai Thomas Unterthiner Mostafa Dehghani Matthias Minderer Georg Heigold Sylvain Gelly et al. 2020. An image is worth 16x16 words: Transformers for image recognition at scale. arXiv preprint arXiv:2010.11929 (2020)."},{"key":"e_1_2_1_13_1","doi-asserted-by":"publisher","DOI":"10.1145\/3555600"},{"key":"e_1_2_1_14_1","doi-asserted-by":"publisher","DOI":"10.1109\/ICCV48922.2021.01204"},{"key":"e_1_2_1_15_1","doi-asserted-by":"publisher","DOI":"10.1109\/GLOBECOM38437.2019.9014297"},{"key":"e_1_2_1_16_1","doi-asserted-by":"publisher","DOI":"10.1109\/CVPR52688.2022.01553"},{"key":"e_1_2_1_17_1","doi-asserted-by":"publisher","DOI":"10.1109\/LCN52139.2021.9525003"},{"key":"e_1_2_1_18_1","volume-title":"Wishield: Privacy against wi-fi human tracking","author":"Hu Jingyang","year":"2024","unstructured":"Jingyang Hu, Hongbo Jiang, Siyu Chen, Qibo Zhang, Zhu Xiao, Daibo Liu, Jiangchuan Liu, and Bo Li. 2024. Wishield: Privacy against wi-fi human tracking. 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