Doreen Riepel
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doreenriepel.bsky.social
Doreen Riepel
@doreenriepel.bsky.social
98 followers 120 following 0 posts
Tenure-Track Faculty at CISPA • Cryptography & Provable Security
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Reposted by Doreen Riepel
eprint.ing.bot
ABE Cubed: Advanced Benchmarking Extensions for ABE Squared (Sven Argo, Marloes Venema, Doreen Riepel, Tim Güneysu, Diego F. Aranha) ia.cr/2025/1230
Abstract. Since attribute-based encryption (ABE) was proposed in 2005, it has established itself as a valuable tool in the enforcement of access control. For practice, it is important that ABE satisfies many desirable properties such as multi-authority and negations support. Nowadays, we can attain these properties simultaneously, but none of these schemes have been implemented. Furthermore, although simpler schemes have been optimized extensively on a structural level, there is still much room for improvement for these more advanced schemes. However, even if we had schemes with such structural improvements, we would not have a way to benchmark and compare them fairly to measure the effect of such improvements. The only framework that aims to achieve this goal, ABE Squared (TCHES ’22), was designed with simpler schemes in mind. In this work, we propose the ABE Cubed framework, which provides advanced benchmarking extensions for ABE Squared. To motivate our framework, we first apply structural improvements to the decentralized ciphertext-policy ABE scheme supporting negations presented by Riepel, Venema and Verma (ACM CCS ‘24), which results in five new schemes with the same properties. We use these schemes to uncover and bridge the gaps in the ABE Squared framework. In particular, we observe that advanced schemes depend on more “variables” that affect the schemes’ efficiency in different dimensions. Whereas ABE Squared only considered one dimension (as was sufficient for the schemes considered there), we devise a benchmarking strategy that allows us to analyze the schemes in multiple dimensions. As a result, we obtain a more complete overview on the computational efficiency of the schemes, and ultimately, this allows us to make better-founded choices about which schemes provide the best efficiency trade-offs for practice. Image showing part 2 of abstract.
July 9, 2025 at 1:22 AM
Reposted by Doreen Riepel
bsky.defeo.lu
The SQIparty starts on Monday, but it's still time to register!

We prepared an exciting program for you with a balanced mix of talks, coding sprints, skillshares and other activities!

www.cig.udl.cat/SQIparty2025...

See you in Lleida!
bsky.defeo.lu Luca De Feo @bsky.defeo.lu · Mar 13
Fancy some isogeny crypto?

Join us for a 3-day workshop on isogeny-based cryptography in Lleida, Catalonia, April 28-30

www.cig.udl.cat/icrypto2025_...

Brought to you by ULleida's Cryptography+Graphs group, the SQIsign team and friends!

Registration and program coming soon
Registration is free!
Cathedral of La Seu Vella in Lleida
April 25, 2025 at 2:14 PM
Reposted by Doreen Riepel
maria.isogeny.club
Really excited to share the Decrypting Diversity Summit happening in Montpellier, France from 17-20 June! The goal of the summit is to promote diversity, inclusivity, and gender equality within the cryptography community. For more info: decryptingdiversity.com
Decrypting Diversity Summit
Decrypting Diversity Summit
decryptingdiversity.com
April 3, 2025 at 12:11 PM
Reposted by Doreen Riepel
proofnerd.bsky.social
Interested in formal verification for cryptography? But not sure where to start?

If you are coming to Eurocrypt, consider joining us for CAPS, the workshop on Computer-Aided Proofs of Security!

caps-workshop.com
CAPS Workshop
caps-workshop.com
April 3, 2025 at 6:36 PM
Reposted by Doreen Riepel
drl3c7er.bsky.social
We have extended the submission deadline for the International Workshop on Foundations and Applications of Privacy-Enhancing Cryptography (PrivCrypt) by two weeks to April 4, 2025, AoE. Please help spread the word and consider submitting your work to join us in Munich in Summer 😎
drl3c7er.bsky.social Daniel Slamanig @drl3c7er.bsky.social · Jan 24
We are organising the International Workshop on Foundations and Applications of Privacy-Enhancing Cryptography (PrivCrypt) - co-located with ACNS 2025 end of June in beautiful Munich.

Submission deadline is March 21, 2025 (AoE).

Please help spread the word! 🙏

privcryptworkshop.github.io
PrivCrypt 2025
privcryptworkshop.github.io
March 20, 2025 at 8:12 AM
Reposted by Doreen Riepel
roeslpa.bsky.social
Join our Applied Crypto group at FAU in Nürnberg as a PhD student or spread the word: we're hiring.

Our work covers many topics in real-world crypto, especially provable security and privacy of modern messaging protocols 🔐✉️

www.jobs.fau.de/jobs/7-phd-p...
7 PhD positions (m/f/d) (salary level 13 TV-L) in Computer Science (full time) and 3 PhD position (m/f/d) (salary level 13 TV-L) in Law (part time, 75%)
www.jobs.fau.de
March 5, 2025 at 9:59 PM
Reposted by Doreen Riepel
eprint.ing.bot
Lattice-Based Updatable Public-Key Encryption for Group Messaging (Joël Alwen, Georg Fuchsbauer, Marta Mularczyk, Doreen Riepel) ia.cr/2025/365
Abstract. Updatable Public-Key Encryption (UPKE) augments the security of PKE with Forward Secrecy properties. While requiring more coordination between parties, UPKE enables much more efficient constructions than full-fledged Forward-Secret PKE. Alwen, Fuchsbauer and Mularczyk (AFM, Eurocrypt’24) presented the strongest security notion to date. It is the first to meet the needs of UPKE’s most important applications: Secure Group Messaging and Continuous Group Key Agreement. The authors provide a very efficient construction meeting their notion with classic security based on the Computational Diffie-Hellman (CDH) assumption in the Random Oracle Model (ROM). In this work we present the first post-quantum secure UPKE construction meeting (a slight relaxation of) the AFM security notion. Based on the Module LWE assumption, our construction is practically efficient. Moreover, public key sizes are about 1/2 and ciphertext sizes around 2/3 of those of the state-of-the-art lattice-based UPKE scheme in the ROM by Abou Haidar, Passelègue and Stehlé – despite only being shown to satisfy a significantly weaker security notion. As the AFM proofs relies on random self-reducibility of CDH, which has no analogue for lattices, we develop a new proof technique for strong UPKE, identifying the core properties required from the underlying (lattice-based) encryption scheme. Image showing part 2 of abstract.
March 4, 2025 at 7:45 AM
Reposted by Doreen Riepel
tiborj.bsky.social
The list of accepted papers and the (preliminary) program for PKC 2025 are now available online:

pkc.iacr.org/2025/program...

We are also delighted to announce that Jesper Buus Nielsen has accepted our invitation to give an invited talk at PKC 2025!

See you at PKC 2025!
pkc.iacr.org
March 2, 2025 at 7:59 PM
Reposted by Doreen Riepel
kennyog.bsky.social
Come join us at the SPIQE workshop in Munich in June! spiqe-workshop.github.io - we are now open for paper submissions and talk proposals on all aspects of secure protocol implementation for the post-quantum era.
Secure Protocol Implementations in the Quantum Era (SPIQE)
Secure Protocol Implementations in the Quantum Era (SPIQE)
spiqe-workshop.github.io
February 28, 2025 at 3:38 PM