Description
The Quantum Fourier Transform is a fundamental tool in quantum cryptanalysis, not only as the building block of Shor's algorithm, but also in attacks against symmetric cryptosystems. Indeed, hidden shift algorithms such as Simon's (FOCS 1994), which rely on the QFT, have been used to obtain attacks on some very specific block cipher structures. The Fourier Transform is also used in classical cryptanalysis, for example in FFT-based linear key-recovery attacks introduced by Collard et al. (ICISC 2007). Whether such techniques can be adapted to the quantum setting has remained so far an open question. In this talk, we will present a new framework for quantum linear key-recovery attacks using the QFT. These attacks loosely follow the classical method of Collard et al., but adapt it to the quantum setting. Classically, the FFT-based attack needs to compute a statistic (experimental correlation) which is higher for a good key guess, and lower for wrong guesses. The quantum attack encodes this statistic in the amplitudes of a quantum state. On some conditions, this can be used to devise new quantum key-recovery attacks which may be applicable to a broader class of ciphers.
Next sessions
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Dissecting CRAFT, a full-round attack
Speaker : Eran Lambooij - Inria
I will present the first full-round key recovery attack on CRAFT, a block cipher introduced at ToSC 2019. The attack builds on the previous observation (ToSC 2026) that the state of CRAFT can be decomposed into two parts that barely exchange information. We transform this property into a dissection attack on the full-round cipher. This shows that in some cases we can elevate the dissection attack[…]-
Cryptography
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Key Attack on the ACDGV Matrix Encryption Scheme
Speaker : Anmoal Porwal - Technical University of Munich
I will present our key-recovery attack on the ACDGV public-key encryption scheme proposed at ASIACRYPT 2024 by Aragon, Couvreur, Dyseryn, Gaborit, and Vinçotte. The secret key is a Gabidulin code hidden by appending random rows and columns and by left- and right-multiplication with invertible matrices. Our attack exploits the resulting algebraic structure to recover an equivalent secret key. It[…]-
Cryptography
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Asymmetric primitive
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Module Learning With Errors and Structured Extrapolated Dihedral Cosets
Speaker : Jinwei Zheng - Télécom Paris
The Module Learning With Errors (MLWE) problem is the fundamental hardness assumption underlying the key encapsulation and signature schemes ML-KEM and ML-DSA, which have been selected by NIST for post-quantum cryptography standardization. Understanding its quantum hardness is crucial for assessing the security of these standardized schemes. Inspired by the equivalence between LWE and[…]-
Cryptography
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