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Topology-Hiding Communication from Minimal Assumptions

Published in TCC 2020

Abstract Topology-hiding broadcast (THB) enables parties communicating over an incomplete network to broadcast messages while hiding the topology from within a given class of graphs. THB is a central tool underlying general topology-hiding secure computation (THC) (Moran et al. TCC’15). Although broadcast is a privacy-free task, it was recently shown that THB for certain graph classes necessitates computational assumptions, even in the semi-honest setting, and even given a single corrupted party.

In this work we investigate the minimal assumptions required for topology-hiding communication: both Broadcast or Anonymous Broadcast (where the broadcaster’s identity is hidden). We develop new techniques that yield a variety of necessary and sufficient conditions for the feasibility of THB/THAB in different cryptographic settings: information theoretic, given existence of key agreement, and given existence of oblivious transfer. Our results show that feasibility can depend on various properties of the graph class, such as connectivity, and highlight the role of different properties of topology when kept hidden, including direction, distance, and/or distance-of-neighbors to the broadcaster.

An interesting corollary of our results is a dichotomy for THC with a public number of at least three parties, secure against one corruption: information-theoretic feasibility if all graphs are 2-connected; necessity and sufficiency of key agreement otherwise.

Eprint: 2021/388

Breaking the Circuit Size Barrier for Secure Computation under Quasi-Polynomial LPN

Published in Eurocrypt 2021

Abstract In this work we introduce a new (circuit-dependent) homomorphic secret sharing (HSS) scheme for any $log/\log\log$-local circuit, with communication proportional only to the width of the circuit and polynomial computation, which is secure assuming the super-polynomial hardness of learning parity with noise (LPN). At the heart of our new construction is a pseudorandom correlation generator (PCG) which allows two parties to locally stretch short seeds into pseudorandom instances of an arbitrary $\log/\log\log$-local additive correlation.

Our main application, and the motivation behind this work, is a generic two-party secure computation protocol for every layered (boolean or arithmetic) circuit of size with total communication $O(\log/\log\log)$ and polynomial computation, assuming the super-polynomial hardness of the standard learning parity with noise assumption (a circuit is layered if its nodes can be partitioned in layers, such that any wire connects adjacent layers). This expands the set of assumptions under which the `circuit-size barrier' can be broken, for a large class of circuits. The strength of the underlying assumption is tied to the sublinearity factor: we achieve communication $O(s/k(s))$ under the $s^{2^{k(s)}}$-hardness of LPN, for any $k(s)\leq (\log\log s)/4$.

Previously, the set of assumptions known to imply a PCG for correlations of degree $\omega(1)$ or generic secure computation protocols with sublinear communication was restricted to LWE, DDH, and a circularly secure variant of DCR.

Eprint: 2021/943

Sublinear Secure Computation from New Assumptions

Published in TCC 2022

Abstract Secure computation enables mutually distrusting parties to jointly compute a function on their secret inputs, while revealing nothing beyond the function output. A long-running challenge is understanding the required communication complexity of such protocols---in particular, when communication can be sublinear in the circuit representation size of the desired function. For certain functions, such as Private Information Retrieval (PIR), this question extends to even sublinearity in the input size.

We develop new techniques expanding the set of computational assumptions for sublinear communication in both settings:

1) [Circuit size] We present sublinear-communication protocols for secure evaluation of general layered circuits, given any 2-round rate-1 batch oblivious transfer (OT) protocol with a particular ``decomposability'' property.

In particular, this condition can be shown to hold for the recent batch OT protocols of (Brakerski et al. Eurocrypt 2022), in turn yielding a new sublinear secure computation feasibility result: from Quadratic Residuosity (QR) together with polynomial-noise-rate Learning Parity with Noise (LPN).
Our approach constitutes a departure from existing paths toward sublinear secure computation, all based on fully homomorphic encryption or homomorphic secret sharing.

2) [Input size.] We construct single-server PIR based on the Computational Diffie-Hellman (CDH) assumption, with polylogarithmic communication in the database input size $n$. Previous constructions from CDH required communication $\Omega(n)$.
In hindsight, our construction comprises of a relatively simple combination of existing tools from the literature.

Eprint: 2023/513

On Low-End Obfuscation and Learning

Published in ITCS 2023

Abstract Most recent works on cryptographic obfuscation focus on the high-end regime of obfuscating general circuits while guaranteeing computational indistinguishability between functionally equivalent circuits. Motivated by the goals of simplicity and efficiency, we initiate a systematic study of "low-end" obfuscation, focusing on simpler representation models and information-theoretic notions of security. We obtain the following results.

[Positive results via “white-box” learning.] We present a general technique for obtaining perfect indistinguishability obfuscation from exact learning algorithms that are given restricted access to the representation of the input function. We demonstrate the usefulness of this approach by obtaining simple obfuscation for decision trees and multilinear read-k arithmetic formulas.

[Negative results via PAC learning.] A proper obfuscation scheme obfuscates programs from a class C by programs from the same class. Assuming the existence of one-way functions, we show that there is no proper indistinguishability obfuscation scheme for k-CNF formulas for any constant k ≥ 3; in fact, even obfuscating 3-CNF by k-CNF is impossible. This result applies even to computationally secure obfuscation, and makes an unexpected use of PAC learning in the context of negative results for obfuscation.

[Separations.] We study the relations between different information-theoretic notions of indistinguishability obfuscation, giving cryptographic evidence for separations between them.

Sublinear-Communication Secure Multiparty Computation does not require FHE

Published in Eurocrypt 2023

Abstract Secure computation enables mutually distrusting parties to jointly compute a function on their secret inputs, while revealing nothing beyond the function output. A long-running challenge is understanding the required communication complexity of such protocols---in particular, when communication can be sublinear in the circuit representation size of the desired function.

Significant advances have been made affirmatively answering this question within the two-party setting, based on a variety of structures and hardness assumptions. In contrast, in the multi-party setting, only one general approach is known: using Fully Homomorphic Encryption (FHE). This remains the state of affairs even for just three parties, with two corruptions.

We present a framework for achieving secure sublinear-communication (N+1)-party computation, building from a particular form of Function Secret Sharing for only N parties. In turn, we demonstrate implications to sublinear secure computation for various function classes in the 3-party and 5-party settings based on an assortment of assumptions not known to imply FHE.

Eprint: 2023/1802

Constrained Pseudorandom Functions from Homomorphic Secret-Sharing

Published in Eurocrypt 2023

Abstract We propose and analyze a simple strategy for constructing 1-key constrained pseudorandom functions (CPRFs) from homomorphic secret sharing. In the process, we obtain the following contributions. First, we identify desirable properties for the underlying HSS scheme for our strategy to work. Second, we show that (most) recent existing HSS schemes satisfy these properties, leading to instantiations of CPRFs for various constraints and from various assumptions. Notably, we obtain the first (1-key selectively secure, private) CPRFs for inner-product and (1-key selectively secure) CPRFs for NC 1 from the DCR assumption, and more. Lastly, we revisit two applications of HSS, equipped with these additional properties, to secure computation: we obtain secure computation in the silent preprocessing model with one party being able to precompute its whole preprocessing material before even knowing the other party, and we construct one-sided statistically secure computation with sublinear communication for restricted forms of computation.

Eprint: 2023/387

Towards Topology-Hiding Computation from Oblivious Transfer

Published in TCC 2023

Abstract Topology-Hiding Computation (THC) enables parties to securely compute a function on an incomplete network without revealing the network topology. It is known that secure computation on a complete network can be based on oblivious transfer (OT), even if a majority of the participating parties are corrupt. In contrast, THC in the dishonest majority setting is only known from assumptions that imply (additively) homomorphic encryption, such as Quadratic Residuosity, Decisional Diffie-Hellman, or Learning With Errors.

In this work we move towards closing the gap between MPC and THC by presenting a protocol for THC on general graphs secure against all-but-one semi-honest corruptions from constant-round constant-overhead secure two-party computation.

Our protocol is therefore the first to achieve THC on arbitrary networks without relying on assumptions with rich algebraic structure. As a technical tool, we introduce the notion of locally simulatable MPC, which we believe to be of independent interest.

Eprint: <a href="https://eprint.iacr.org/2023/849>2023/849</a>

Topology-Hiding Communication from Minimal Assumptions

Published in Journal of Cryptology

Abstract Topology-hiding broadcast (THB) enables parties communicating over an incomplete network to broadcast messages while hiding the topology from within a given class of graphs. THB is a central tool underlying general topology-hiding secure computation (THC) (Moran et al. TCC’15). Although broadcast is a privacy-free task, it was recently shown that THB for certain graph classes necessitates computational assumptions, even in the semi-honest setting, and even given a single corrupted party.

In this work we investigate the minimal assumptions required for topology-hiding communication: both Broadcast or Anonymous Broadcast (where the broadcaster’s identity is hidden). We develop new techniques that yield a variety of necessary and sufficient conditions for the feasibility of THB/THAB in different cryptographic settings: information theoretic, given existence of key agreement, and given existence of oblivious transfer. Our results show that feasibility can depend on various properties of the graph class, such as connectivity, and highlight the role of different properties of topology when kept hidden, including direction, distance, and/or distance-of-neighbors to the broadcaster.

An interesting corollary of our results is a dichotomy for THC with a public number of at least three parties, secure against one corruption: information-theoretic feasibility if all graphs are 2-connected; necessity and sufficiency of key agreement otherwise.

Eprint: 2021/388

A Note on Low-Communication Secure Multiparty Computation via Circuit Depth-Reduction

Published in TCC 2024

Abstract We consider the graph-theoretic problem of removing (few) nodes from a directed acyclic graph in order to reduce its depth. While this problem is intractable in the general case, we provide a variety of algorithms in the case where the graph is that of a circuit of fan-in (at most) two, and explore applications of these algorithms to secure multiparty computation with low communication. Over the past few years, a paradigm for low-communication secure multiparty computation has found success based on decomposing a circuit into low-depth ``chunks''. This approach was however previously limited to circuits with a ``layered'' structure. Our graph-theoretic approach extends this paradigm to \emph{all} circuits. In particular, we obtain the following contributions:

[Fractionally linear-communication MPC in the correlated randomness model.] We provide an $N$-party protocol for computing an $n$-input, $m$-output $\F$-arithmetic circuit with $s$ internal gates (over any basis of binary gates) with communication complexity $(\frac{2}{3}s + n + m)\cdot N\cdot\log |\F|$, which can be improved to $((1+\epsilon)\cdot\frac{2}{5}s+n+m)\cdot N\cdot\log |\F|$ (at the cost of increasing the computational overhead from a small constant factor to a large one). Previously, comparable protocols either used more than $s\cdot N\cdot \log |\F|$ bits of communication, required super-polynomial computation, were restricted to layered circuits, or tolerated a sub-optimal corruption threshold.

[Sublinear-Communication MPC.] Assuming the existence of $N$-party Homomorphic Secret Sharing for logarithmic depth circuits (respectively doubly logarithmic depth circuits), we show there exists sublinear-communication secure $N$-party computation for \emph{all} $\log^{1+o(1)}$-depth (resp.~$(\log\log)^{1+o(1)}$-depth) circuits. Previously, this result was limited to $(\mathcal{O}(\log))$-depth (resp.~$(\mathcal{O}(\log\log))$-depth) circuits, or to circuits with a specific structure (\eg layered).

[The $\bm$-OT complexity of MPC.] We introduce the ``\emph{$N\choose 1$-OT complexity of MPC}'' of a function $f$, denoted $C_N(f)$, as the number of oracle calls required to securely compute $f$ in the $N\choose 1$-OT hybrid model. We establish the following upper bound: for every $N\geq 2$, $C_N(f) \leq (1+g(N))\cdot \frac{2 |f|}{5}$, where $g(N)$ is an explicit vanishing function.

We also obtain additional contributions to reducing the amount of bootstrapping for fully homomorphic encryption, and to other types of sublinear-communication MPC protocols such as those based on correlated symmetric private information retrieval.

Eprint: 2024/1473

Rate-1 Arithmetic Garbling From Homomorphic Secret Sharing

Published in TCC 2024

Abstract We present a new approach to garbling arithmetic circuits using techniques from homomorphic secret sharing, obtaining constructions with high rate that support free addition gates. In particular, we build upon non-interactive protocols for computing distributed discrete logarithms in groups with an easy discrete-log subgroup, further demonstrating the versatility of tools from homomorphic secret sharing. Relying on distributed discrete log for the Damgård-Jurik cryptosystem (Roy and Singh,~\emph{Crypto `21}), whose security follows from the decisional composite residuosity assumption (DCR), we get the following main results:

[Two ciphertexts per multiplication, from IND-CPA security of Damgård-Jurik.] Assuming the Damgård-Jurik cryptosystem is semantically secure (which follows from DCR), there is a garbling scheme for circuits with $B$-bounded integer arithmetic using only two ciphertexts per multiplication. The total bit-size of the resulting garbled circuit is $(n + 2s_\times+2D_\times)\cdot (\zeta + 1) \cdot \log N$, where $n$ is the number of inputs, $s_\times$ is the number of multiplications, $D_\times$ is the multiplicative depth of the circuit, $N$ is an RSA modulus and $N^{\zeta-1}$ is roughly the bound $B$ on the magnitude of wire values in the computation.

[One ciphertext per multiplication, from KDM security of Damgård-Jurik.] Assuming the Damgård-Jurik encryption scheme remains secure given encryption of the key and its inverse, the construction achieves rate-$1$. The total bit-size of the resulting garbled circuit is $(n + s_\times + 1) \cdot (\zeta + 1) \cdot \log N$, where the parameters are as above, except $N^{\zeta-2}$ is the magnitude bound.

As a side result, we show that our scheme based on IND-CPA security achieves rate $3/5$ for levelled circuits.

Eprint: 2024/820

Fast Public-Key Silent OT and More from Constrained Naor-Reingold

Published in Eurocrypt 2024

Abstract Pseudorandom Correlation Functions (PCFs) allow two parties, given correlated evaluation keys, to locally generate arbitrarily many pseudorandom correlated strings, e.g. Oblivious Transfer (OT) correlations, which can then be used by the two parties to jointly run secure computation protocols.

In this work, we provide a novel and simple approach for constructing PCFs for OT correlation, by relying on constrained pseudorandom functions for a class of constraints containing a weak pseudorandom function (wPRF). We then show that tweaking the Naor-Reingold pseudorandom function and relying on low-complexity pseudorandom functions allow us to instantiate our paradigm. We further extend our ideas to obtain efficient public-key PCFs, which allow the distribution of correlated keys between parties to be non-interactive: each party can generate a pair of public/secret keys, and any pair of parties can locally derive their correlated evaluation key by combining their secret key with the other party's public key.

In addition to these theoretical contributions, we detail various optimizations and provide concrete instantiations of our paradigm relying on the Boneh-Ishai-Passelègue-Sahai-Wu wPRF and the Goldreich-Applebaum-Raykov wPRF. Putting everything together, we obtain public-key PCFs with a throughput of 15k-40k OT/s, which is of a similar order of magnitude to the state-of-the-art interactive PCFs and about 4 orders of magnitude faster than state-of-the-art public-key PCFs.

As a side result, we also show that public-key PCFs can serve as a building block to construct reusable designated-verifier non-interactive zero-knowledge proofs (DV-NIZK) for NP. Combined with our instantiations, this yields simple and efficient reusable DV-NIZKs for NP in pairing-free groups.

Eprint: 2024/178

Instantiating the Hash-Then-Evaluate Paradigm: Strengthening PRFs, PCFs, and OPRFs

Published in SCN 2024

Abstract We instantiate the hash-then-evaluate paradigm for pseudorandom functions (PRFs), PRF(k, x) := wPRF(k, RO(x)), which builds a PRF PRF from a weak PRF wPRF via a public pre-processing random oracle RO. In applications to secure multiparty computation (MPC), only the low-complexity wPRF performs secret-depending operations. Our construction replaces RO by f (kH, elf(x)), where f is a non-adaptive PRF and the key kH is public and thus known to the distinguishing adversary.

We show that, perhaps surprisingly, several existing weak PRF candidates are plausibly also secure when their inputs are generated by f (kH, elf(.)). Firstly, analogous cryptanalysis applies (because pseudorandomness of f implies good statistical properties) and/or secondly an attack against the weak PRF with such pseudorandom inputs generated by f would imply surprising results such as key agreement from the hardness of the high-noise version of the Learning Parity with Noise (LPN) when implementing both wPRF and f from this assumption.

Our simple transformation of replacing RO(·) public pre-processing by f (kH, elf(x)) public pre-processing applies to the entire family of PRF-style functions. Specifically, we obtain results for oblivious PRFs, which are a core building block for password-based authenticated key exchange (PAKE) and private set intersection (PSI) protocols, and we also obtain results for pseudorandom correlation functions (PCF), which are a key tool for silent oblivious transfer (OT) extension.

Eprint: 2023/1145

<a href="https://pierremeyercs.github.io/2025/245" rel="permalink">Silent Circuit Relinearisation: Sublinear-Size (Boolean and Arithmetic) Garbled Circuits from DCR </a>

Published in Crypto 2025

Abstract We introduce a general template for building garbled circuits with low communication, under the decisional composite residuosity (DCR) assumption. For the case of layered Boolean circuits, we can garble a circuit of size $s$ with communication proportional to $O(s/\log\log s)$ bits, plus an additive factor that is polynomial in the security parameter. For layered arithmetic circuits with $B$-bounded integer computation, we obtain a similar result: the garbled arithmetic circuit has size $O(s/\log\log s)\cdot (\lambda + \log B)$ bits, where $\lambda$ is the security parameter. These are the first constructions of general-purpose, garbled circuits with sublinear size, without relying on heavy tools like indistinguishability obfuscation or attribute-based and fully homomorphic encryption.

To achieve these results, our main technical tool is a new construction of a form of homomorphic secret sharing where some of the inputs are semi-private, that is, known to one of the evaluating parties. Through a new relinearisation technique that allows performing arbitrary additions and multiplications on semi-private shares, we build such an HSS scheme that supports evaluating any function of the form $C(x)\cdot C'(y)$, where $C$ is any polynomially-sized circuit applied to the semi-private input $x$, and $C'$ is a restricted-multiplication (or, NC1) circuit applied to the private input $y$. This significantly broadens the expressiveness of prior known HSS constructions.

Eprint: 2025/245

Privately Constrained PRFs from DCR: Puncturing and Bounded Waring Rank

Published in TCC 2025

Abstract A privately constrained pseudorandom function (pCPRF) is a PRF with the additional property that one can derive a constrained key that allows evaluating the PRF only on inputs satisfying a constraint predicate , without revealing itself or leaking information about the PRF’s output on inputs that do not satisfy the constraint.

Existing privately constrained PRFs face significant limitations: either (1) they rely on assumptions known to imply fully-homomorphic encryption or indistinguishability obfuscation, (2) they support only highly restricted classes of constraints—for instance, no known group-based pCPRF even supports the simple class of puncturing constraints (where the constrained key permits evaluation on all but one point while hiding the punctured point), or (3) they are limited to polynomial-size input domains. A long-standing open question has been whether one can construct a privately constrained PRF from group-based assumptions for more expressive classes of constraints. In this work, we present a pCPRF based on the decisional composite residuosity (DCR) assumption that supports a highly expressive class of predicates, namely constraints with polynomially bounded Waring rank, which notably includes puncturing.

From a technical perspective, our work follows the general template of Couteau, Meyer, Passelègue, and Riahinia (Eurocrypt'23), who constructed a pCPRF from group-based homomorphic secret-sharing but were limited to inner-product constraints in the constraint-hiding setting. Leveraging novel techniques for computing with distributed discrete logarithms (DDLog), we enable the non-interactive authentication of powers of linear combinations of shares of some value. This, in turn, allows us to express constraints with polynomially bounded Waring rank.

Our construction is single-key, selectively secure, and supports an exponential-size domain.

Eprint: 2025/230

Instantiating the Hash-Then-Evaluate Paradigm: Strengthening PRFs, PCFs, and OPRFs

Published in Cryptography and Communications

Abstract We instantiate the hash-then-evaluate paradigm for pseudorandom functions (PRFs), PRF(k, x) := wPRF(k, RO(x)), which builds a PRF PRF from a weak PRF wPRF via a public pre-processing random oracle RO. In applications to secure multiparty computation (MPC), only the low-complexity wPRF performs secret-depending operations. Our construction replaces RO by f (kH, elf(x)), where f is a non-adaptive PRF and the key kH is public and thus known to the distinguishing adversary.

We show that, perhaps surprisingly, several existing weak PRF candidates are plausibly also secure when their inputs are generated by f (kH, elf(.)). Firstly, analogous cryptanalysis applies (because pseudorandomness of f implies good statistical properties) and/or secondly an attack against the weak PRF with such pseudorandom inputs generated by f would imply surprising results such as key agreement from the hardness of the high-noise version of the Learning Parity with Noise (LPN) when implementing both wPRF and f from this assumption.

Our simple transformation of replacing RO(·) public pre-processing by f (kH, elf(x)) public pre-processing applies to the entire family of PRF-style functions. Specifically, we obtain results for oblivious PRFs, which are a core building block for password-based authenticated key exchange (PAKE) and private set intersection (PSI) protocols, and we also obtain results for pseudorandom correlation functions (PCF), which are a key tool for silent oblivious transfer (OT) extension.

Eprint: 2023/1145

Maintaining Sublinear Locality Over Time: Adaptively Secure MPC on a Reusable Hidden Graph

Published in Eurocrypt 2026

Abstract Communication locality of an n-party protocol measures the maximum degree of the communication graph induced by the protocol execution. While secure multi-party computation (MPC) with small, sublinear locality exists in the static-corruption setting, this goal seems nearly paradoxical in the adaptive-corruption setting: Even against fail-stop adversaries, small neighbour sets of honest parties lie vulnerable to identification and corruption.

Surprisingly, Chandran et al. [ITCS ’15] showed that for a single MPC execution, sublinear locality and adaptive security can be simultaneously achieved, assuming honest-to-honest channels are hidden from the adversary. Their solution works in the ``hidden-graph model'', where a fresh, initially hidden, low-degree graph is being used in each round. In turn, the combined degree grows with every round—inherently limiting the approach to a single-shot MPC execution, and sublinear total rounds.

This raises the following question, which is the focus of our work:

Is it possible to maintain sublinear locality over an unbounded number of executions facing adaptive adversaries?

In this work, we provide an affirmative answer in two settings:

– First, we consider semi-honest adversaries and information-theoretic security, and construct reusable MPC with polylog(n) locality.

– Second, we consider fail-stop adversaries and computational security, and construct reusable MPC with Õ(n^{2/3}) locality.

Our results are obtained by devising low-locality protocols while hiding important information about the graph topology, enabling the parties to reuse a single hidden graph. As an independent contribution, this serves as new results for adaptively secure topology-hiding computation (Moran et al. [TCC ’15]).

Computationally Succinct Authentication from DCR: Attribute-Based Laconic Function Evaluation and More

Published in Eurocrypt 2026

Abstract We present the first construction of attribute-based laconic function evaluation (AB-LFE) from the decisional composite residuosity (DCR) assumption. This yields the first example of computationally succinct secure computation from a group-based assumption, avoiding reliance on noisy lattice assumptions such as LWE. Our construction builds on recent work in fully homomorphic MACs and homomorphic secret sharing by Ishai, Li and Lin (FOCS 2025) and Meyer, Orlandi, Roy, and Scholl (Crypto 2025), which we extend by constructing a fully homomorphic MAC for packed vector operations, where the evaluation time of one party is independent of the vector length.

As applications, we obtain full-fledged laconic function evaluation (LFE) from the combination of DCR and standard LWE, avoiding the need for sub-exponential modulus-to-noise ratio LWE used in previous work. We also obtain the first constrained pseudorandom function whose master evaluation key is succinct in the constraint.

These results highlight the unexplored power of group-based cryptography for succinct secure computation.

Eprint: 2025/2307

talks

Kernelization algorithms for some link stream editing problems

Published:

Abstract Given a link stream L and a positive integer k, the Sparse Split Link Stream Editing problem asks to transform L into a link stream which consists of a clique plus isolated vertices during an interval and is linkless outside that interval, by performing at most k edge insertions and deletions.

Distributed Discrete Logarithms and Applications – Part I

Published:

Here are the slides and video of my talk. Here are the slides and video of part II, by Lawrence Roy.

Abstract In this two-parts talk we will introduce the "distributed discrete logarithm" problem (DDLog) and present many of the exciting applications it has enabled in recent years. DDLog is a crucial tool in recent share-conversion protocols and has enabled many exciting such as MPC with sub-linear complexity, homomorphic- and function secret-sharing, pseudorandom correlation generators, garbling, and more. We will give examples of DDLog protocol from established assumptions, and dive into some of the applications.

teaching

Teaching experience 1

Undergraduate course, University 1, Department, 2014

This is a description of a teaching experience. You can use markdown like any other post.

Teaching experience 2

Workshop, University 1, Department, 2015

This is a description of a teaching experience. You can use markdown like any other post.