Protocol Labs Research

Yolan Romailler

Research Engineer / drand


MEng in Information and Communication Technologies, 2017

HES-SO Haute école spécialisée de Suisse occidentale

BSc in Mathematics, 2015

École polytechnique fédérale de Lausanne (EPFL)

Yolan is an applied cryptographer delving into (and dwelling on) cryptography, secure coding, and other fun things. He has previously spoken at Black Hat USA, NorthSec, GopherCon, Real World Crypto and DEF CON on topics including automation in cryptography, public keys vulnerabilities, elliptic curves, post-quantum cryptography, functional encryption, open source security, distributed randomness, and more! He introduced the first practical fault attack against the EdDSA signature scheme and orchestrated the full disclosure with PoC of the CurveBall vulnerability. Nowadays he’s working on the distributed randomness project, drand, studying pairing-based cryptography, distributed key generation, and threshold systems. His most recent work was focused around Timelock Encryption.

Areas of Expertise

Threshold Cryptography, Digital Signatures, Distributed Key Generation


tlock: Practical timelock encryption based on threshold BLS
Real World Crypto 23 / 2023.03.29 / Tokyo, Japan
Timelock encryption based on drand
Protocol Labs Research Talks / 2022.09.14
drand: Publicly verifiable randomness explained
May Contain Hackers 2022 / 2022.07.25 / Zeewolde, The Netherlands


2023-02-13 / Report
tlock: Practical timelock encryption from threshold BLS
We present a practical construction and implementation of timelock encryption, in which a ciphertext is guaranteed to be decryptable only after some specified time has passed. We employ an existing threshold network, the League of Entropy, implementing threshold BLS [BLS01, B03] in the context of Boneh and Franklin’s identity-based encryption (IBE).
Nicolas Gailly , Kelsey Melissaris, Yolan Romailler