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Secure Cloud Storage: Modularization, Network Adversaries and Adaptive Corruptions
to appear at EUROCRYPT 2026
Jonas Janneck, Doreen Riepel
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The Algebraic Isogeny Model: A General Model with Applications to SQIsign and Key Exchanges
We introduce the Algebraic Isogeny Model (AIM){:} an algebraic model, akin to the Algebraic Group Model in the group setting, for …
Marius A. Aardal, Andrea Basso, Doreen Riepel
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Intermundium-DL: Assessing the Resilience of Current Schemes to Discrete-Log-Computation Attacks on Public Parameters
We consider adversaries able to perform a nonzero but small number of discrete logarithm computations, as would be expected with …
Mihir Bellare, Doreen Riepel, Laura Shea
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Public-Algorithm Substitution Attacks: Subverting Hashing and Verification
We study the possibility of algorithm substitution attacks (ASAs) on functions with no secret-key material, such as hash functions, and …
Mihir Bellare, Doreen Riepel, Laura Shea
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Verifiable and Provably Secure Machine Unlearning
Machine unlearning aims to remove points from the training dataset of a machine learning model after training; for example when a user …
Thorsten Eisenhofer, Doreen Riepel, Varun Chandrasekaran, Esha Ghosh, Olga Ohrimenko, Nicolas Papernot
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Count Corruptions, Not Users: Improved Tightness for Signatures, Encryption and Authenticated Key Exchange
In the multi-user with corruptions (muc) setting there are n≥1 users, and the goal is to prove that, even in the face of an adversary …
Mihir Bellare, Doreen Riepel, Stefano Tessaro, Yizhao Zhang
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The Concrete Security of Two-Party Computation: Simple Definitions, and Tight Proofs for PSI and OPRFs
This paper initiates a concrete-security treatment of two-party secure computation. The first step is to propose, as target, a simple, …
Mihir Bellare, Rishabh Ranjan, Doreen Riepel, Ali Aldakheel
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Tightly-Secure Group Key Exchange with Perfect Forward Secrecy
In this work, we present a new paradigm for constructing Group Authenticated Key Exchange (GAKE). This result is the first tightly …
Emanuele Di Giandomenico, Doreen Riepel, Sven Schäge
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On the Tight Security of the Double Ratchet
The Signal Protocol is a two-party secure messaging protocol used in applications such as Signal, WhatsApp, Google Messages and …
Daniel Collins, Doreen Riepel, Si An Oliver Tran
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ISABELLA: Improving Structures of Attribute-Based Encryption Leveraging Linear Algebra
Attribute-based encryption (ABE) is a powerful primitive that has found applications in important real-world settings requiring access …
Doreen Riepel, Marloes Venema, Tanya Verma
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