Tessera

Ashkan Tariverdi is a new visitor in COSIC, welcome! His research focuses on extending the CovFUZZ framework, a coverage-guided fuzzer for 4G and 5G protocol testing. #choosecosic

📢The COSIC newsletter for June-July is now online! Discover what our researchers have been working on over the past two months, from cybersecurity research to publications, awards, and events. Read more: www.esat.kuleuven.be/cosic/sites/...

Omid Mirzamohammadi and Jan Bobolz wrote a very nice blog post based on their paper “Multi-Verifier Keyed-Verification Anonymous Credentials,” co-authored by Emad Heydari Beni, Anja Lehmann, Cavit Özbay, and Mahdi Sedaghat. Read it here: www.esat.kuleuven.be/cosic/blog/m...

At COSIC, we believe research should be shared. The lecture recordings from the 18th International COSIC Course on Cybersecurity and Cryptography are now available on YouTube. The playlist includes most presentations from the 2026 edition. Enjoy! www.youtube.com/playlist?lis...

COSIC Course 2026 - YouTube

This playlist contains the lectures from the 18th edition of the International COSIC Course on Cybersecurity and Cryptography. It includes most of the lectur...

youtube.com

We’re excited to announce the 7th edition of the Leuven Isogeny Days (Sept 16–18, 2026)! Registration is now open, join us! More info & signup: esat.kuleuven.be/cosic/projec... #LID #Isogeny #IsogenyDays

This week in COSIC... On Thursday Jelena Zelenovic (COSIC) will give a seminar on "Post-Quantum Discovery as a Governance Capability: Evidence-Based Cryptographic Visibility and Exposure Prioritisation in a Critical Service Provider": www.esat.kuleuven.be/cosic/?post_...

Events Archive - COSIC

esat.kuleuven.be

ePrint Updates @eprint.ing.bot · 3w ago

Is there a Russian link behind a password manager used by the Brussels government? According to Bart Preneel, there is a real risk that Russian authorities could access password data, even if there is no hard proof this is happening today. www.tijd.be/politiek-eco... (paywall)

Schuilt er een Russische connectie achter uw wachtwoordkluis?

Een digitale ‘wachtwoordkluis’ die in ons land wordt gebruikt bij de Brusselse overheid, heeft Russische roots. Dat blijkt uit internationaal onderzoek waaraan De Tijd deelnam. Het doet vragen rijzen ...

tijd.be

The Isogeny Problems (Wouter Castryck, Luca De Feo, Steven D. Galbraith, Péter Kutas, Krijn Reijnders, Benjamin Wesolowski) ia.cr/2026/1431

Abstract. This work contains an exposition of the seven foremost unsolved problems in the domain of isogeny-based cryptography, obtained by asking eleven experts in isogeny-based cryptography what they considered to be the most important unsolved problems in isogeny-based cryptography, and curated down to the seven problems in this document. For each problem, an expert wrote a short write-up giving the precise statements and descriptions per problem.

ePrint Updates @eprint.ing.bot · 3w ago

Compressed Post-Quantum Silent OT from Isogenies (Pouria Fallahpour, Arthur Herlédan Le Merdy, Mahshid Riahinia) ia.cr/2026/1444

$Abstract. Oblivious transfer (OT) is a foundational tool in secure computation. Random OT-correlated pairs of the form (r₀, r₁) and (b, r_(b)), where $r_0,r_1,b \stackrel{{}_\$}{\leftarrow} \{0,1\}$, significantly speed up secure computation protocols. Pseudorandom correlation functions (PCFs), introduced by Boyle et al. (FOCS 2020), are an efficient means of non-interactively generating correlated pairs. In a PCF, two parties store short keys that are used to locally generate large amounts of correlated pairs. While pre-quantum PCFs for OT achieve highly compact key sizes (e.g., 30 kB), a significant gap remains in the post-quantum regime, where existing solutions rely on lattices or learning-parity-with-noise-style assumptions and yield much larger keys. We construct compact post-quantum PCFs for OT. Our construction has key sizes in the range of 100 kB, approaching the compactness of pre-quantum PCFs and seven times smaller than the most compact state-of-the-art post-quantum alternatives. The key size of our PCF remains invariant regardless of the target number of OTs, in contrast to prior alternatives. We estimate a throughput of 7 OTs per second for our PCF. We additionally provide a security proof in the quantum random oracle model, constituting the first such analysis of a post-quantum PCF. The core of our construction is a new, compact constrained pseudorandom function (CPRF) for inner-product membership predicates. Its security is based on a natural extension of the parallelization problem, which we introduce as the parallelization problem with auxiliary inputs. We provide an extensive analysis of this assumption as well as an implementation of our construction.$ Image showing part 2 of abstract.

ePrint Updates @eprint.ing.bot · 4mo ago

Divide-and-Pair: Faster subgroup membership testing for elliptic curves (Yu Dai, Youssef El Housni, Dimitri Koshelev, Krijn Reijnders) ia.cr/2026/749

Abstract. Subgroup membership testing (SMT) on an elliptic curve with non-trivial cofactor is essential to prevent small-subgroup attacks in cryptographic protocols. In the existing literature, there exist two non-trivial methods for SMT on elliptic curves with modest cofactor (typically a power of 2): Pornin’s approach tests membership by repeatedly dividing by prime divisors of the cofactor (mostly halving), finishing with Legendre symbols; Koshelev’s approach replaces all divisions with Tate pairings (possibly in the quadratic extension of the base field), but requires non-degeneracy conditions that are not always met. In this paper, we observe that both approaches sit at the extremes of a single division-pairing trade-off. The resulting method, Divide-and-Pair, is always at least as fast as either Pornin’s or Koshelev’s method and strictly faster in many cases. We instantiate Divide-and-Pair on five curves in widespread use, including Curve25519, Curve448, GC256A, Fourℚ and JubJub. Our Go implementation, built on the open-source gnark-crypto library, achieves significant speedups over state-of-the-art tests, namely of 2.4× on Curve25519, of 1.6× on Curve448, of 1.7× on GC256A, of 8.2× on Fourℚ and of 7.5× on JubJub.

COSIC @cosic.bsky.social · 3w ago

"The Commission wants to push ahead with mandatory age verification. Once again the advice of security and privacy experts is ignored. See our 2026 open letter that is still fully relevant: csa-scientist-open-letter.org/ageverif-Feb... (B Preneel on LinkedIn) www.linkedin.com/posts/bart-p...

csa-scientist-open-letter.org

COSIC @cosic.bsky.social · 3w ago

Lakshya Chopra is a new visitor at COSIC: he will be doing research on authenticated encryption modes that remain secure even when nonces are reused, or when unverified plaintext is released before verification. Welcome! #choosecosic

Bart Preneel on LinkedIn on the approval of Chatcontrol 1.0: www.linkedin.com/posts/bart-p...

EU Parliament greenlights Chat Control 1.0 – Breyer: “Our children lose out” | Bart Preneel | 13 comments

If you thought democracy was about a majority of MEPs - after careful consideration of all inputs - approving a proposal, well the EU is different. After two clear no votes of the Parliament, 314 no v...

linkedin.com

Bart Preneel on LinkedIn on the approval of Chatcontrol 1.0: www.linkedin.com/posts/bart-p...

De Morgen and De Volkskrant bring an excellent report on the approval of Chatcontrol 1.0 https://lnkd.in/emH3azck https://lnkd.in/eUzVAUyF We have written to dozens of media contacts in the past… |...

linkedin.com

"Europees parlement stemt in controversiële spoedprocedure alsnog voor het checken van berichten op beelden van kindermisbruik" www.volkskrant.nl/politiek/eur...

Europees parlement stemt in controversiële spoedprocedure alsnog voor het checken van berichten op beelden van kindermisbruik

Het Europees parlement is ermee akkoord gegaan dat niet-versleutelde berichtendiensten, zoals e-mail en Instagram-chats, gescreend kunnen worden op beelden van kindermisbruik. Eerder was dit voorstel ...

volkskrant.nl

EU backs scanning of messages for abuse images, even using AI on new content. Bart Preneel warns in De Morgen: the error rate could mean “tens of millions of false positives per day” and calls the approach disproportionate, with risks of broader surveillance. www.demorgen.be/tech-ai/euro...

Europees Parlement stemt in controversiële spoedprocedure alsnog voor het checken van berichten op beelden van kindermisbruik

Het Europees Parlement gaat ermee akkoord dat niet-versleutelde berichtendiensten, zoals e-mail en Instagram-chats, gescreend kunnen worden naar beelden van kindermisbruik. Eerder was dit voorstel weg...

demorgen.be

The COSIC Seminar on "Can We Tolerate Small Side-Channel Leakages: The Role of Registers in Glitch-Stopping Circuits" by our researcher Artemii Ovchinnikov is now available on our YouTube channel: www.youtube.com/watch?v=wa3C...

COSIC Seminar "Can We Tolerate Small Side-Channel Leakages: The Role.." (Artemii Ovchinnikov, COSIC)

YouTube video by COSIC - Computer Security and Industrial Cryptography

youtube.com

Aditi Singh is an intern at COSIC and wrote a blog post on privacy-aware basketball analytics. 🏀🔐 How can AI model in‑game decisions, scale insights with synthetic data, and protect sensitive information via federated learning & contextual integrity? www.esat.kuleuven.be/cosic/blog/l...

Literature Review: The Basketball Analysis Problem - COSIC

COSIC - Literature Review: The Basketball Analysis Problem (COSIC Cryptography Blog )

esat.kuleuven.be

Let's welcome João Azevedo to our research group! João is starting a PhD on privacy-enhancing technologies, including issuer-hiding anonymous credentials and strengthened fuzzy extractors, for privacy-preserving Self-Sovereign Identity systems. Welcome! #choosecosic

Selman Eroglu is a new intern working on publicly verifiable secret sharing, distributed key generation, and threshold cryptography. Welcome! #choosecosic

Kaarlo Lahti is a new intern working on the project "Pairwise Independence of the AES", studying the way the AES behaves when subject to a "triple-wise" attack. #choosecosic

Abel Stuker earned his BA at VUB and is now joining COSIC as an intern, where he is working on the security analysis of the Car Connectivity Consortium Digital Key 4.0 specification. Welcome, Abel! #choosecosic

Our researcher Ilja Siroš attended #DCOSSIoT and shares insights from an inspiring keynote on Spiking Neural Networks. 🧠⚡ Dive into the blog: www.esat.kuleuven.be/cosic/blog/s...

Spiking Neural Networks - COSIC

COSIC - Spiking Neural Networks (COSIC Cryptography Blog )

esat.kuleuven.be

EU Chat control is back on the table. Bart Preneel warns in De Morgen: scanning private messages at scale risks treating all citizens as suspects, without solid scientific basis for AI detection. #Privacy matters. Proportionality matters. www.demorgen.be/tech-ai/chat... (paywall)

Chat control duikt voor derde keer op in Europees Parlement

Chat control leek in maart politiek afgevoerd, maar de Europese Commissie wil het dinsdag toch weer door het parlement duwen. Onder het mom van de strijd tegen online kindermisbruik zouden techbedrijv...

demorgen.be

This week in COSIC... Today Artemii Ovchinnikov (COSIC) will be giving a seminar on "Can We Tolerate Small Side-Channel Leakages: The Role of Registers in Glitch-Stopping Circuits". More info on www.esat.kuleuven.be/cosic/?post_...

Events Archive - COSIC

esat.kuleuven.be

ePrint Updates @eprint.ing.bot · last mo.

The COSIC Seminar on "0-RTT Integrated in SPDM for Large-Scale AI Super-Clusters" by Rongkuan He (COSIC) is now available on our YouTube channel: youtu.be/_bt4se7vu-s

COSIC Seminar "0-RTT Integrated in SPDM for Large-Scale AI Super-Clusters" (Rongkuan He, COSIC)

YouTube video by COSIC - Computer Security and Industrial Cryptography

youtu.be

The Generalised Tate Pairing over any field (Jonathan Komada Eriksen) ia.cr/2026/1325

Abstract. We generalise a pairing on elliptic curves over finite fields, called the generalised Tate pairing, which is defined in terms of an arbitrary endomorphism of the curve, with certain trace requirements. We rederive this pairing from group cohomology, which allows us to generalise the pairing to principally polarized abelian varieties over any field, endomorphisms of any trace, and prove perfectness using a general duality theorem.

Antoine Kahn is doing an internship in COSIC and is working on secure detection of illegal content. Welcome! #choosecosic

Francisco Manuel López López is a new intern in COSIC: he is working on Verifiable Secret Sharing schemes. "I chose to join COSIC to collaborate with world-class experts in applied cryptography. It is the ideal environment to advance my research in cryptography". #choosecosic