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1. HERS: Homomorphically Encrypted Representation Search

   https://doi.org/10.1109/TBIOM.2021.3139866  

   Engelsma, Joshua J.; Jain, Anil K.; Boddeti, Vishnu Naresh (July 2022, IEEE Transactions on Biometrics, Behavior, and Identity Science)
2. Private Hierarchical Governance for Encrypted Messaging

   Namavari, Armin; Wang, Barry; Menda, Sanketh; Nassi, Ben; Tyagi, Nirvan; Grimmelmann, James; Zhang, Amy X; Ristenpart, Thomas (May 2024, Proceedings of the IEEE Symposium on Security and Privacy)

   The increasing harms caused by hate, harassment, and other forms of abuse online have motivated major platforms to explore hierarchical governance. The idea is to allow communities to have designated members take on moderation and leadership duties; meanwhile, members can still escalate issues to the platform. But these promising approaches have only been explored in plaintext settings where community content is public to the platform. It is unclear how one can realize hierarchical governance in the huge and increasing number of online communities that utilize end-to-end encrypted (E2EE) messaging for privacy. We propose the design of private, hierarchical governance systems. These should enable similar levels of community governance as in plaintext settings, while maintaining cryptographic privacy of content and governance actions not reported to the platform. We design the first such system, taking a layered approach that adds governance logic on top of an encrypted messaging protocol; we show how an extension to the message layer security (MLS) protocol suffices for achieving a rich set of governance policies. Our approach allows developers to rapidly prototype new governance features, taking inspiration from a plaintext system called PolicyKit. We report on an initial prototype encrypted messaging system called MlsGov that supports content-based community and platform moderation, elections of community moderators, votes to remove abusive users, and more. 

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3. Committee Moderation on Encrypted Messaging Platforms

   Pattison, Alistair; Hopper, Nicholas (May 2023, IEEE Symposium on Security and Privacy Posters)
4. Efficient Algorithms for Encrypted All-gather Operation

   https://doi.org/10.1109/IPDPS49936.2021.00045  

   Lahijani, Mehran Sadeghi; Naser, Abu; Wu, Cong; Gavahi, Mohsen; Hoang, Viet Tung; Wang, Zhi; Yuan, Xin (May 2021, 2021 IEEE International Parallel and Distributed Processing Symposium (IPDPS))

   null (Ed.)
5. Practical Volume-Based Attacks on Encrypted Databases

   https://doi.org/10.1109/EuroSP48549.2020.00030  

   Poddar, Rishabh; Wang, Stephanie; Lu, Jianan; Popa, Raluca Ada (September 2020, 2020 IEEE European Symposium on Security and Privacy (EuroS&P))

   null (Ed.)

   Recent years have seen an increased interest towards strong security primitives for encrypted databases (such as oblivious protocols) that hide the access patterns of query execution and reveal only the volume of results. However recent work has shown that even volume leakage can enable the reconstruction of entire columns in the database. Yet existing attacks rely on a set of assumptions that are unrealistic in practice for example they (i) require a large number of queries to be issued by the user or (ii) assume certain distributions on the queries or underlying data (e.g. that the queries are distributed uniformly at random or that the database does not contain missing values). In this work we present new attacks for recovering the content of individual user queries assuming no leakage from the system except the number of results and avoiding the limiting assumptions above. Unlike prior attacks our attacks require only a single query to be issued by the user for recovering the keyword. Furthermore our attacks make no assumptions about the distribution of issued queries or the underlying data. Instead our key insight is to exploit the behavior of real-world applications. We start by surveying 11 applications to identify two key characteristics that can be exploited by attackers-(l) file injection and (ii) automatic query replay. We present attacks that leverage these two properties in concert with volume leakage independent of the details of any encrypted database system. Subsequently we perform an attack on the real Gmail web client by simulating a server-side adversary. Our attack on Gmail completes within a matter of minutes demonstrating the feasibility of our techniques. We also present three ancillary attacks for situations when certain mitigation strategies are employed. 

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