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 ·
Code
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
Function secret sharing (FSS) has seen many applications in privacy-preserving systems.
An important feature in these systems is the ability to enforce access control privately.
We formalize this notion and provide several constructions for access control in FSS.
We evaluate several applications of access control for FSS, including PIR with access control and faster anonymous communication.
Paper ·
Slides ·
Code
Talk given at: IRIF laboratory at the CNRS and University of Paris Cité, IEEE S&P.
Mix-nets offer great scalability properties and can be used to instantiate anonymous broadcast (and communication) efficiently.
We design and build
Trellis, a new mix-net based anonymous broadcast system that offers:
(1) concrete efficiency,
(2) network robustness in the face of malicious servers,
(3) scalability with added servers,
and (4) security even when a majority of mix servers are malicious.
Paper ·
Slides ·
Code
Tor can be significantly slower compared to regular browsing largely due to the way
in which Tor routes traffic over the internet.
Tor requires routing packets through multiple
relays forming a "circuit."
Traffic congestions between relays on a Tor circuit can lead to delays, increasing latency, and hindering user experience.
ShorTor is an overlay for the Tor network which can help find
shorter paths between relays using a trick deployed by major CDNs.
ShorTor reduces latency between relays, is incrementally deployable, and minimally impacts the security of Tor.
Paper ·
Slides ·
Code