Publications by Serge Vaudenay

SILBE: An Updatable Public Key Encryption Scheme from Lollipop Attacks

We present a new post-quantum Public Key Encryption scheme (PKE) named Supersingular Isogeny Lollipop Based Encryption or SILBE. SILBE is obtained by leveraging the generalized lollipop attack of Castryck and Vercauteren on the M-SIDH Key exchange by Fouot ...

Springer Nature Switzerland2025

Non-Transferable Anonymous Tokens by Secret Binding

Serge Vaudenay, Laurane Chloé Angélina Marco, Abdullah Talayhan

Non-transferability (NT) is a security notion which ensures that credentials are only used by their intended owners. Despite its importance, it has not been formally treated in the context of anonymous tokens (AT) which are lightweight anonymous cre- denti ...

Association for Computing Machinery (ACM)2024

Cryptographic Administration for Secure Group Messaging

Serge Vaudenay, Daniel Patrick Collins

Many real-world group messaging systems delegate group administration to the application level, failing to provide formal guarantees related to group membership. Taking a cryptographic approach to group administration can prevent both implementation and pr ...

Berkeley2023

Extractable Witness Encryption for the Homogeneous Linear Equations Problem

Serge Vaudenay, Bénédikt Minh Dang Tran

Witness encryption is a cryptographic primitive which encrypts a message under an instance of an NP language and decrypts the ciphertext using a witness associated with that instance. In the current state of the art, most of the witness encryption construc ...

Springer2023

Making Classical (Threshold) Signatures Post-quantum for Single Use on a Public Ledger

Serge Vaudenay, Laurane Chloé Angélina Marco, Abdullah Talayhan

The Bitcoin architecture heavily relies on the ECDSA signature scheme which is broken by quantum adversaries as the secret key can be computed from the public key in quantum polynomial time. To mitigate this attack, bitcoins can be paid to the hash of a pu ...

2023

A Gapless Post-quantum Hash Proof System in the Hamming Metric

Serge Vaudenay, Bénédikt Minh Dang Tran

A hash proof system (HPS) is a form of implicit proof of membership to a language. Out of the very few existing post-quantum HPS, most are based on languages of ciphertexts of code-based or lattice-based cryptosystems and inherently suffer from a gap cause ...

2023

On Active Attack Detection in Messaging with Immediate Decryption

Serge Vaudenay, Simone Maria Stefano Colombo, Loïs Evan Huguenin-Dumittan, Khashayar Barooti, Daniel Patrick Collins

Springer2023

Private Message Franking with After Opening Privacy

Serge Vaudenay, Iraklis Leontiadis

Recently Grubbs et al. [GLR17] initiated the formal study of message franking protocols. This new type of service launched by Facebook, allows the receiver in a secure messaging application to verifiably report to a third party an abusive message some send ...

2023

Anonymous Tokens with Stronger Metadata Bit Hiding from Algebraic MACs

Serge Vaudenay, Fatma Betül Durak

On the one hand, the web needs to be secured from malicious activities such as bots or DoS attacks; on the other hand, such needs ideally should not justify services tracking people's activities on the web. Anonymous tokens provide a nice tradeoff between ...

2023

Solving the Learning Parity with Noise Problem Using Quantum Algorithms

Serge Vaudenay, Bénédikt Minh Dang Tran

The Learning Parity with Noise (LPN) problem is a famous cryptographic problem consisting in recovering a secret from noised samples. This problem is usually solved via reduction techniques, that is, one reduces the original instance to a smaller one befor ...

Springer2022

Optimal Symmetric Ratcheting for Secure Communication

Serge Vaudenay, Andrea Felice Caforio, Daniel Patrick Collins, Hailun Yan

To mitigate state exposure threats to long-lived instant messaging sessions, ratcheting was introduced, which is used in practice in protocols like Signal. However, existing ratcheting protocols generally come with a high cost. Recently, Caforio et al. pro ...

OXFORD UNIV PRESS2022

SwissCovid in the Perspective of Its Goals

Martin Vuagnoux, Serge Vaudenay

SwissCovid is the Swiss digital contact tracing app, which was deployed to help fighting against the COVID-19 pandemic. After a year of activity, it is high time to evaluate how effective it has been in its mission. At the highest peak, about 22% of the Sw ...

2022

On IND-qCCA security in the ROM and its applications CPA security is sufficient for TLS 1.3

Serge Vaudenay, Loïs Evan Huguenin-Dumittan

Bounded IND-CCA security (IND-qCCA) is a notion similar to the traditional IND-CCA security, except the adversary is restricted to a constant number q of decryption/decapsulation queries. We show in this work that IND-qCCA is easily obtained from any passi ...

2022

Towards Efficient LPN-Based Symmetric Encryption

Serge Vaudenay, Thomas Locher, Sonia Mihaela Bogos, Dario Korolija

Due to the rapidly growing number of devices that need to communicate securely, there is still significant interest in the development of efficient encryption schemes. It is important to maintain a portfolio of different constructions in order to enable a ...

Springer International Publishing AG2021

Towards Witness Encryption Without Multilinear Maps

Serge Vaudenay, Gwangbae Choi

Current proposals of extractable witness encryption are based on multilinear maps. In this paper, we propose a new construction without. We propose the notion of hidden group with hashing and make an extractable witness encryption from it. We show that the ...

2021

Beyond Security and Efficiency: On-Demand Ratcheting with Security Awareness

Serge Vaudenay, Andrea Felice Caforio, Fatma Betül Durak

Secure asynchronous two-party communication applies ratcheting to strengthen privacy, in the presence of internal state exposures. Security with ratcheting is provided in two forms: forward security and post-compromise security. There have been several suc ...

2021

Post-Compromise Security in Self-Encryption

Serge Vaudenay, Gwangbae Choi, Fatma Betül Durak

In self-encryption, a device encrypts some piece of information for itself to decrypt in the future. We are interested in security of self-encryption when the state occasionally leaks. Applications that use self-encryption include cloud storage, when a cli ...

2021

FAST: Secure and High Performance Format-Preserving Encryption and Tokenization

Serge Vaudenay

We propose a new construction for format-preserving encryption. Our design provides the flexibility for use in format-preserving encryption (FPE) and for static table-driven tokenization. Our algorithm is a substitution-permutation network based on random ...

2021

FO-like Combiners and Hybrid Post-Quantum Cryptography

Serge Vaudenay, Loïs Evan Huguenin-Dumittan

Combining several primitives together to offer greater security is an old idea in cryptography. Recently, this concept has resurfaced as it could be used to improve trust in new Post-Quantum (PQ) schemes and smooth the transition to PQ cryptography. In par ...

2021

New Attacks on LowMC instances with a Single Plaintext/Ciphertext pair

Serge Vaudenay, Subhadeep Banik, Khashayar Barooti, Hailun Yan

Cryptanalysis of the LowMC block cipher when the attacker has access to a single known plaintext/ciphertext pair is a mathematically challenging problem. This is because the attacker is unable to employ most of the standard techniques in symmetric cryptogr ...

2021