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cosic.bsky.social
COSIC
@cosic.bsky.social
300 followers 38 following 700 posts
COSIC provides a broad expertise in digital security and strives for innovative security solutions.
COSIC is headed by Bart Preneel.
https://www.esat.kuleuven.be/cosic/
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Reposted by COSIC
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TreeCast: Multi-Party Key Establishment Protocol for IoT Devices (Supriyo Banerjee, Sayon Duttagupta) ia.cr/2025/2021
Abstract. Secure communication in the Internet of Things (IoT) requires lightweight protocols that scale across unicast, multicast, and broadcast settings. Existing solutions typically depend on centralized gateways, which introduce single points of failure and scalability limitations. We present TreeCast, a decentralized group key establishment protocol that organizes devices in a binary tree and derives communication keys through hybrid key exchange. The protocol achieves efficient and scalable key management, supporting dynamic membership with localized rekeying. We provide a formal security analysis and proof, showing that TreeCast achieves authentication, session key confidentiality, post-compromise security, and partial forward secrecy. In addition, we evaluate computational and storage costs of the protocol, demonstrating logarithmic scalability in both communication overhead and device state. By enabling a single framework for unicast, multicast, and broadcast communication, our approach bridges the gap between cryptographic rigor and practical IoT deployment. TreeCast provides a deployable, communication-oriented solution to secure large-scale IoT networks. Image showing part 2 of abstract.
November 1, 2025 at 2:20 AM
cosic.bsky.social
Closing the PQCSA Workshop on "PQC Migration & Supply Chain Readiness for Automotive". The day ends with group roadmap building, live feedback, and consensus on next steps.
www.esat.kuleuven.be/cosic/events...
#pqcsa #pqc #postquantum #quantum #escar
November 7, 2025 at 3:16 PM
cosic.bsky.social
Group sessions to draft PQC transition steps and milestones, guided by the experts - at the PQCSA Workshop on "PQC Migration & Supply Chain Readiness for the Automotive Industry".
www.esat.kuleuven.be/cosic/events...
#pqcsa #pqc #postquantum #quantum #escar
November 7, 2025 at 1:43 PM
cosic.bsky.social
At the PQCSA Workshop on PQC Migration, Jan Klaußner (BDR, Germany) gives a brief introduction before participants move on to group sessions to draft PQC transition steps and milestones, guided by the experts.
www.esat.kuleuven.be/cosic/events...
#pqcsa #pqc #postquantum #quantum #escar
November 7, 2025 at 1:41 PM
cosic.bsky.social
Aysajan Abidin (COSIC, KU Leuven) is organizing the PQCSA Workshop on "PQC Migration & Supply Chain Readiness for the Automotive Industry" in Frankfurt today. A day full of interesting talks and group discussions.
www.esat.kuleuven.be/cosic/events...
#pqcsa #pqc #postquantum #quantum #escar
November 7, 2025 at 12:57 PM
cosic.bsky.social
Melissa Azouaoui (NXP, Germany) giving a talk on "Beyond Quantum Resilience: Embedded Security with and for PQC" at the PQCSA Workshop on "PQC Migration & Supply Chain Readiness for the Automotive Industry" today.
www.esat.kuleuven.be/cosic/events...
#pqcsa #pqc #postquantum #quantum #escar
November 7, 2025 at 12:54 PM
cosic.bsky.social
We are honoring the selection of the Belgian cipher #Rijndael as the Advanced Encryption Standard (#AES) at the IEEE Milestone Award Ceremony on November 18, 2025 in Heverlee, Belgium.
Interested? Sign up here: rijndael-ieeemilestone.cs.ru.nl/index
November 7, 2025 at 11:01 AM
cosic.bsky.social
COSIC Prof Bart Preneel giving a lecture on "The Quantum Threat and its Impact on the Automotive Industry" at the PQCSA "PQC Migration & Supply Chain Readiness for the Automotive Industry" in Frankfurt today.
www.esat.kuleuven.be/cosic/events...
#pqcsa #pqc #postquantum #quantum #escar
November 7, 2025 at 10:44 AM
cosic.bsky.social
Takahito Yoshizawa (COSIC, KU Leuven) talking about the impact of PQC in V2X at the PQCSA Workshop on "PQC Migration & Supply Chain Readiness for the Automotive Industry" in Frankfurt today.
#pqcsa #pqc #postquantum #quantum #escar
November 7, 2025 at 10:24 AM
cosic.bsky.social
🏅On 24 November FWO and FNRS are awarding the FWO-Excellence Prizes. COSIC Professor Ingrid Verbauwhede (KU Leuven) will receive the "Excellentieprijs dr. A. De Leeuw-Damry-Bourlart 2025 in de Toegepaste Wetenschappen".
🖊️https://fwo.idloom.events/uitreiking-excellentieprijzen-2025
November 7, 2025 at 10:13 AM
cosic.bsky.social
Karthikeyan Bhargavan from Cryspen gave the keynote talk at the PQCSA workshop on "PQC Migration & Supply Chain Readiness for the Automotive Industry" this morning in Frankfurt.
www.esat.kuleuven.be/cosic/events...
#pqcsa #pqc #postquantum #quantum #escar
November 7, 2025 at 9:11 AM
cosic.bsky.social
This week in COSIC... Finally our PQCSA event in Frankfurt is happening! The workshop on "PQC Migration & Supply Chain Readiness for the Automotive Industry" will take place on Friday.
www.esat.kuleuven.be/cosic/events...
November 3, 2025 at 4:03 PM
cosic.bsky.social
Valerio Ardizio is the newest member of Frederik Vercauteren's team!
"I chose COSIC because of its welcoming, inspiring, and stimulating research environment, as well as the outstanding expertise of the researchers who are part of this group."
#choosecosic
November 3, 2025 at 4:01 PM
cosic.bsky.social
Great news: the paper "Integral cryptanalysis in characteristic $p$" by our researchers Tim Beyne & Michiel Verbauwhede will receive the Best Theory and Early Career Award at #Asiacrypt 2025!
asiacrypt.iacr.org/2025/program...
November 3, 2025 at 10:20 AM
cosic.bsky.social
Next week we are organizing the #PQCSA "PQC Migration & Supply Chain Readiness for the Automotive Industry" Workshop in Frankfurt (Germany).
👉You can still register (last chance): www.esat.kuleuven.be/cosic/events...
October 31, 2025 at 1:13 PM
cosic.bsky.social
The EU will scrap the controversial mass surveillance clause from its proposed child abuse regulation. Privacy experts like Bart Preneel have long warned it’s "like putting a camera in every home."
#ChatControl #Privacy #EU
www.standaard.be/buitenland/e...
EU ziet af van omstreden controle van chatberichten in de strijd tegen online kindermisbruik
De Europese Unie zal de omstreden massassurveillance-clausule schrappen uit het wetsvoorstel in de strijd tegen online kindermisbruik. Verschillende lidstaten vinden het een disproportionele schending van de privacy.
www.standaard.be
October 31, 2025 at 10:49 AM
cosic.bsky.social
Exciting news! 🎉 COSIC Professor Vincent Rijmen has been selected as one of the finalists for the Belgian Cyber Security Awards 2025, a great recognition of his lasting impact and expertise in the Belgian cybersecurity community.🔐
#CyberSecurity #COSIC #KULeuven
October 31, 2025 at 8:56 AM
Reposted by COSIC
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Blind zkSNARKs for Private Proof Delegation and Verifiable Computation over Encrypted Data (Mariana Gama, Emad Heydari Beni, Jiayi Kang, Jannik Spiessens, Frederik Vercauteren) ia.cr/2024/1684
Abstract. In this paper, we show for the first time it is practical to privately delegate proof generation of zkSNARKs proving up to 2²⁰ R1CS constraints to a single server. We achieve this by homomorphically computing zkSNARK proof generation, an approach we call blind zkSNARKs. We formalize the concept of blind proofs, analyze their cryptographic properties and show that the resulting blind zkSNARKs remain sound when compiled using BCS compilation. Garg et al. gave a similar framework at CRYPTO 2024, but no practical instantiation for proving non-trivial computations was known. By delegating proof generation, we are able to reduce client computation time from 10 minutes to mere seconds, while server computation time remains limited to 20 minutes. We also propose a practical construction for vCOED supporting constraint sizes four orders of magnitude larger than the current state-of-the-art verifiable FHE-based approaches. These results are achieved by optimizing Fractal for the GBFV homomorphic encryption scheme, e.g. by designing specialized homomorphic circuits with two dimensional NTTs. Furthermore, we make the proofs publicly-verifiable by appending a zero-knowledge Proof of Decryption (PoD). We propose a new construction for PoDs, optimized for low proof generation time, exploiting modulus and ring switching in GBFV; these techniques might be of independent interest. Finally, we implement the latter protocol in C and report on execution time and proof sizes. Image showing part 2 of abstract.
October 18, 2024 at 2:40 AM
Reposted by COSIC
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Keyed-Verification Anonymous Credentials with Highly Efficient Partial Disclosure (Omid Mirzamohammadi, Jan Bobolz, Mahdi Sedaghat, Emad Heydari Beni, Aysajan Abidin, Dave Singelee, Bart Preneel) ia.cr/2025/041
Abstract. An anonymous credential (AC) system with partial disclosure allows users to prove possession of a credential issued by an issuer while selectively disclosing a subset of their attributes to a verifier in a privacy-preserving manner. In keyed-verification AC (KVAC) systems, the issuer and verifier share a secret key. Existing KVAC schemes rely on computationally expensive zero-knowledge proofs during credential presentation, with the presentation size growing linearly with the number of attributes. In this work, we propose two highly efficient KVAC constructions that eliminate the need for zero-knowledge proofs during the credential presentation and achieve constant-size presentations. Our first construction adapts the approach of Fuchsbauer et al. (JoC’19), which achieved constant-size credential presentation in a publicly verifiable setting using their proposed structure-preserving signatures on equivalence classes (SPS-EQ) and set commitment schemes, to the KVAC setting. We introduce structure-preserving message authentication codes on equivalence classes (SP-MAC-EQ) and designated-verifier set commitments (DVSC), resulting in a KVAC system with constant-size credentials (2 group elements) and presentations (4 group elements). To avoid the bilinear groups and pairing operations required by SP-MAC-EQ, our second construction uses a homomorphic MAC with a simplified DVSC. While this sacrifices constant-size credentials (n + 2 group elements, where n is the number of attributes), it retains constant-size presentations (2 group elements) in a pairingless setting. We formally prove the security of both constructions and provide open-source implementation results demonstrating their practicality. We extensively benchmarked our KVAC protocols and, additionally, bechmarked the efficiency of our SP-MAC-EQ scheme against the original SPS-EQ scheme, showcasing significant performance improvements. Image showing part 2 of abstract.
January 13, 2025 at 1:40 AM
Reposted by COSIC
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LightCROSS: A Secure and Memory Optimized Post-Quantum Digital Signature CROSS (Puja Mondal, Suparna Kundu, Supriya Adhikary, Angshuman Karmakar) ia.cr/2024/1929
Abstract. CROSS is a code-based post-quantum digital signature scheme based on a zero-knowledge (ZK) framework. It is a second-round candidate of the National Institute of Standards and Technology’s additional call for standardizing post-quantum digital signatures. The memory footprint of this scheme is prohibitively large, especially for small embedded devices. In this work, we propose various techniques to reduce the memory footprint of the key generation, signature generation, and verification by as much as 50%, 52%, and 74%, respectively, on an ARM Cortex-M4 device. Moreover, our memory-optimized implementations adapt the countermeasure against the recently proposed (ASIACRYPT-24) fault attacks against the ZK-based signature schemes.
November 29, 2024 at 2:45 AM
Reposted by COSIC
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Complex Elections via Threshold (Fully) Homomorphic Encryption (Charlotte Bonte, Georgio Nicolas, Nigel P. Smart) ia.cr/2025/1482
Abstract. We discuss how Fully Homomorphic Encryption (FHE), and in particular the TFHE scheme, can be used to define an e-voting scheme for the Alternative Vote (AV) election system. This system has a more complex tallying phase than traditional First-Past-The-Post (FPTP) election variants. Previous work on e-voting schemes that used homomorphic encryption has focused on FPTP systems only, and utilized mainly linearly homomorphic encryption. We show, by using FHE, that more complex electoral systems such as AV can also be supported by homomorphic encryption. We show security of our protocol by considering it as a simple MPC functionality, and we also show practicality by presenting some experimental runtimes using the tfhe-rs library.
August 20, 2025 at 2:10 PM
cosic.bsky.social
We dove into the fascinating world of cryptography at the #Kinderuniversiteit in Leuven last weekend! The kids unraveled ancient codes, discovered how spies sent secret messages, and became real codebreakers. 🕵️‍♂️✨
October 30, 2025 at 10:58 AM
cosic.bsky.social
A trip down memory lane with Ingrid Verbauwhede:
"A picture from history: ASIC design of a domain-specific programmable co-processor for DES (Data Encryption Standard) in 2.4micron CMOS, 2 layers of metal, licensed from imec to CryptechNV"
Source: www.linkedin.com/posts/ingrid...
October 30, 2025 at 9:27 AM
cosic.bsky.social
Welcome to Stelios Manasidis, who is visiting us and researching hardware implementations of post-quantum signature schemes.
#choosecosic
October 29, 2025 at 12:41 PM
cosic.bsky.social
COSIC researcher Can Ozkan presented "Penetration Testing in Wind Farms: Detection and Impact Analysis" at IEEE PES ISGT Europe 2025 in Malta on 21st October.
ieee-isgt-europe.org/conference-p...
Conference program – IEEE ISGT Europe 2025
ieee-isgt-europe.org
October 29, 2025 at 12:37 PM