@ur4ndom.dev.bsky.social
Cryptography @ 3MI Labs PhD @ COSIC, KU Leuven CTF @ organizers
Check out the new open letter signed by more than 450 scientists who have serious concerns on the latest (July 2025) version of the chat control proposal. csa-scientist-open-letter.org/Sep2025
09.09.2025 09:00 — 👍 4 🔁 5 💬 0 📌 0The EU wants to spend your money to assemble a giant mass surveillance machine with little effect on harm against children. Chat Control is not effective, weakens security for all and does not respect privacy. Contact your EU representatives and let them know.
csa-scientist-open-letter.org/Sep2025
Abstract. Multiparty fully homomorphic encryption (MPFHE) is a generalization of (multi-key) fully homomorphic encryption ((MK)FHE) that lives on the cusp between multiparty computation (MPC) and FHE, enabling a computation over encrypted data using multiple keys. However, contrary to MKFHE it seeks to reduce the noise inflation based on the number of parties by allowing the parties to first compute shared data in MPC before executing the computation in FHE. Generally, MPFHE protocols have required ad-hoc constructions and adaptations to already existing protocols. In this work we present a new framework that standardizes the approach of MPFHE to allow the use of a broad spectrum of MPC and FHE protocols, while eliminating the noise inflation based on the participating number of parties. This presents the first ever multiparty FHE protocol which allows an arbitrary number of participants. We then show a case study of this using the FINAL scheme and show that we reduce the required key material by 40-99.9% compared to the MKFHE FINAL scheme, FINALLY, 8-71% compared to the AKÖ scheme, and 65-70% compared to the Park-Rovira scheme. Moreover, we reduce the bootstrapping time for the AKÖ, Park-Rovira, and KMS schemes by 75-99.7%.
Image showing part 2 of abstract.
Multiparty FHE Redefined: A Framework for Unlimited Participants (Robin Jadoul, Barry van Leeuwen, Oliver Zajonc) ia.cr/2025/965
28.05.2025 05:59 — 👍 1 🔁 1 💬 0 📌 0
Congratulations to our researcher Robin Jadoul for successfully defending his PhD thesis on "Secure Multiparty Computation, Inside and Out of the Head"! 🎓🥳🎉
31.01.2025 11:44 — 👍 15 🔁 3 💬 0 📌 0
About 250 scientists from 31 countries have signed another open letter homes.esat.kuleuven.be/~preneel/Ope... criticizing the latest EU #chatcontrol draft
See x.com/bpreneel1/st... for full post
Also check out the original challenge, and several other great ones straight from the source.
github.com/dicegang/dic...
I also made a cpython issue for it, and hopefully I'll manage to find some time to propose a PR to fix it too :)
github.com/python/cpyth...
I did a CTF writeup from the "diligent auditor" pyjail challenge from last weeks DiceCTF quals.
It goes a bit deeper into some python import mechanics and has several tricks that avoid the audit hook system to read files and directories and execute arbitrary commands.
ur4ndom.dev/posts/2024-0...
Abstract. In this work, we extend the MPC-in-the-head framework, used in recent efficient zero-knowledge protocols, to work over the ring ℤ_(2^(k)), which is the primary operating domain for modern CPUs. The proposed schemes are compatible with any threshold linear secret sharing scheme and draw inspiration from MPC protocols adapted for ring operations. Additionally, we explore various batching methodologies, leveraging Shamir’s secret sharing schemes and Galois ring extensions, and show the applicability of our approach in RAM program verification. Finally, we analyse different options for instantiating the resulting ZK scheme over rings and compare their communication costs.
ZK-for-Z2K: MPC-in-the-Head Zero-Knowledge Proofs for ℤ_(2^(k))
(Lennart Braun, Cyprien Delpech de Saint Guilhem, Robin Jadoul, Emmanuela Orsini, Nigel P. Smart, Titouan Tanguy) ia.cr/2023/1057
"This space intentionally left blank"
06.07.2023 11:56 — 👍 4 🔁 0 💬 1 📌 0
