Welcome to my digital corner!

Sacha Servan-Schreiber
3s [at] mit.edu

I'm a Ph.D. student at MIT CSAIL, advised by Srini Devadas. My research is focused on applied cryptography (and more recently on theoretical cryptography). Previously, I was also interested in algorithms, computer graphics, and database systems. I spent the fall and spring semesters of 2023-2024 visiting Geoffroy Couteau at IRIF. Before MIT, I was an undergrad at Brown University.
In my spare time I like to make art, cycle, and run around the Charles River.

GitHub · CV

Recent projects
QuietOT: OT extension with a public-key setup
Oblivious transfer is at the heart of secure computation protocols. In an OT extension, two parties can perform some secure computation protocol to generate "seeds" that they can then expand into many OT instances. In QuietOT, this setup process can be computed non-interactively using only the public key of the other party. Previous approaches offering a similar setup required computationally expensive techniques. In contrast, QuietOT generates millions of OTs per second, on commodity hardware. Separately, QuietOT offers a precomputability property that allows one party to generate all OT messages before even knowing the identity of the other party, which can be useful in practical settings.

Paper · Slides · Code
Constrained PRFs from weaker assumptions
Constrained PRFs (CPRFs) have many applications. Until recently, we only knew how to construct CPRFs for simple constraint predicates under standard assumptions. We examine the case of inner product predicates (which give rise to a number of other useful predicates such as predicates described by constant-degree polynomials). We show that it is possible to construct constraint-hiding CPRFs for inner product predicates (1) unconditionally in the random oracle model, (2) under DDH, and (3) from the minimal assumption that one-way functions exist under certain restrictions. Previously, CPRFs for inner product constraints were only known from the DCR and LWE assumptions, or from non-standard assumptions. Our constructions are also the first to be concretely practical.

Paper · Slides · Code
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© 2024 Sacha Servan-Schreiber