Cryptography Research Group
Who We Are
The MongoDB Cryptography Research Group conducts research in cryptography and works with MongoDB engineering and product teams to transfer and deploy the latest advances in cryptography and privacy.Research Areas
Encrypted search
Encrypted search algorithms (ESAs) enable efficient searching on encrypted data and are used in technologies like Queryable Encryption. Practical ESAs balance performance and information leakage, making leakage analysis and suppression essential for assessing security guarantees.
Secure multi-party computation
Secure multi-party computation enables multiple parties to collaboratively compute a function on their respective inputs while keeping the inputs private and revealing only the function’s output. A commonly studied example is computing the set intersection or set union of privately held datasets.
Encrypted distributed systems
Encrypted distributed and concurrent algorithms enable the design of distributed systems with cryptographic security guarantees. This area specifically examines the interplay between key distributed system concepts, such as concurrency and consistency, and their impact on security guarantees.
Our Team
Archita Agarwal
Senior Research ScientistArchita’s research bridges the gap between encrypted search and distributed computing.
Zachary Espiritu
Senior Research EngineerZachary’s research focuses on both cryptographic design and cryptanalysis of encrypted search algorithms.
Marilyn George
Senior Research ScientistMarilyn’s research focuses on understanding the efficiency and security trade-offs of the real-world use of cryptography.
Seny Kamara
Distinguished Research Scientist and Head of ResearchSeny has worked extensively on the design and cryptanalysis of encrypted search algorithms.
Tarik Moataz
Principal Research ScientistTarik’s research interests are in the area of cryptography and computer security with a focus on encrypted search.
Andrew Park
Senior Research EngineerAndrew’s research focuses on practical design of cryptographic protocols.
Archita received her Ph.D. in computer science from Brown University in 2021. Before joining MongoDB, she was an assistant professor of computer science at Denison University in Ohio. Her work focuses on bridging the gaps between encrypted search and distributed computing. Specifically, she designs and analyzes end-to-end encrypted, distributed, and concurrent systems. She was the first to design encrypted distributed dictionaries and key-value stores, two primitives that underlie encrypted distributed databases. Her work also highlights the fundamental connections between cryptography and distributed/concurrent systems, such as how security, consistency, and efficiency interact with each other. Archita is also interested in augmenting her encrypted database designs with additional privacy-preserving features, such as differentially private analytical queries and GDPR-compliant access requests.
Zachary received bachelor's and master's degrees in computer science from Brown University, graduating in 2021. Prior to MongoDB, Zachary worked with the Cloud Security Group and Encrypted Systems Lab at Brown University, specializing in cryptography, data structures, algorithms, and computer systems. Zachary's research focuses on cryptanalysis of encrypted search protocols and designing practical tooling and infrastructure to help cryptographers understand and design protocols. Zachary has created multiple frameworks for rapidly prototyping and evaluating cryptographic schemes. He has also designed and implemented attacks against various types of encrypted databases.
Marilyn received her Ph.D. in computer science from Brown University’s Encrypted Systems Lab in 2022. Her research focuses on understanding the efficiency and security trade-offs associated with the real-world use of cryptography, with an emphasis on encrypted search. Her work addresses the theoretical limits of encrypted search algorithms and introduces new techniques for their design. Marilyn’s work showed, for the first time, how to design dynamic leakage suppression techniques, resulting in efficient zero and almost-zero leakage encrypted search algorithms. Marilyn is also interested in the legal and social aspects of secure systems. In earlier work, she designed a GDPR compliance tool for legacy databases as well as an encrypted database for public policy studies.
Seny is head of research at MongoDB. He has worked extensively on the design and cryptanalysis of encrypted search algorithms, which are efficient algorithms for searching on end-to-end encrypted data. His work first showed how to search on encrypted data in optimal time, how to formalize the security of searchable symmetric encryption (SSE), how to optimally search on dynamic encrypted data, and how to cryptanalyze property-preserving encryption. He maintains interests in various aspects of theory and systems, including applied and theoretical cryptography, data structures and algorithms, and technology policy.
Before joining MongoDB, Seny was an associate professor of computer science at Brown University. Before that, he was a research scientist at Microsoft Research. In 2017, he co-founded Aroki Systems and served as its chief scientist until its acquisition by MongoDB. He has been appointed to two National Academies of Sciences committees on encryption and surveillance and has provided testimony to the U.S. House of Representatives Financial Services Committee and to the Committee on Space, Science, and Technology. He has given keynotes at the IACR’s Annual International Cryptology Conference (CRYPTO), the ACM’s Symposium on Principles of Distributed Computing (PODC), and the ACM’s Conference on Advances in Financial Technologies (AFT). In 2022, Seny and his collaborators won the ACM Conference on Computer and Communications Security’s (CCS) Test-of-Time Award for their work on dynamic searchable symmetric encryption.
Tarik manages the Cryptography Research Group at MongoDB. Prior to joining MongoDB, he was a co-founder and chief technology officer at Aroki Systems (acquired by MongoDB) and before that, he was a visiting scientist and a postdoctoral researcher at Brown University in the Encrypted Systems Lab (ESL). His research is in the area of cryptography and computer security, with a focus on encrypted search. He works primarily on the design and cryptanalysis of encrypted search algorithms that offer different efficiency, security, and expressiveness trade-offs. His work introduced the first worst-case sublinear Boolean searchable symmetric encryption scheme, the first structured encryption-based encrypted relational database, the notion of leakage suppression along with the first volume-hiding structured encryption schemes, and the first volumetric leakage attacks against exact keyword search.
Tarik served on the organizing committee of the first workshop on the Theory and Practice of Encrypted Search (TPES) as well as ICERM’s workshop on encrypted search. He has also served on the program committees of IACR’s Annual International Cryptology Conference (CRYPTO), IACR’s Annual International Conference on the Theory and Applications of Cryptology (Eurocrypt), and the ACM’s Conference on Computer and Communications Security (CCS).
Andrew graduated from Brown University with a B.S. in applied mathematics and an M.S in computer science in 2020. Prior to MongoDB, he was a research assistant in the Encrypted Systems Lab at Brown University, as well as a research assistant at Cylab at Carnegie Mellon University.
His research focuses on the practical design of cryptographic protocols and their application to privacy-preserving technologies. His prior work spans areas such as Oblivious RAM (ORAM) and Private Information Retrieval (PIR), and their applications to solve interesting real-world problems.
Research Papers
Bayesian Leakage Analysis: A Framework for Analyzing Leakage in Encrypted Search
Zachary Espiritu, Seny Kamara, and Tarik MoatazIACR Communications in Cryptology, 2025
This work proposes a theoretical framework for analyzing and better understanding leakage.
Concurrent Encrypted Multimaps
Archita Agarwal, Seny Kamara, and Tarik MoatazAsiacrypt, 2024
This work initiates the study of encrypted data structures in the concurrent setting.
MAPLE: MArkov Process Leakage attacks on Encrypted Search
Seny Kamara, Abdelkarim Kati, Tarik Moataz, Jamie DeMaria, Andrew Park, and Amos TreiberPrivacy Enhancing Technologies Symposium, 2024
This work studies query equality leakage on dependent queries and presents two new attacks that can work either as known-distribution or known-sample attacks.
Synq: Public Policy Analytics Over Encrypted Data
Zachary Espiritu, Marilyn George, Seny Kamara, and Lucy QinIEEE Symposium on Security and Privacy, 2024
We design Synq, a system that supports analytics over encrypted data while accounting for the usability considerations of institutions conducting public policy studies.
Design and Analysis of a Stateless Database Encryption Scheme
Seny Kamara and Tarik MoatazTechnical report, 2023
In this work, we design the first encrypted document database scheme focusing on designing a scheme that is practical with respect to real-world constraints.
An Overview of MongoDB’s Queryable Encryption
Technical report, 2023An overview of Queryable Encryption, its design goals, threat model, security properties, and performance.
Injection-Secure Structured and Searchable Symmetric Encryption
Ghous Amjad, Seny Kamara and Tarik MoatazAsiacrypt, 2024
We propose the first injection-secure multi-map encryption scheme and use it as a building block to design the first injection-secure searchable symmetric encryption (SSE) scheme.