Improved quantum attack on Type-1 Generalized Feistel Schemes and Its application to CAST-256

Generalized Feistel Schemes (GFS) are important components of symmetric ciphers, which have been extensively researched in classical setting. However, the security evaluations of GFS in quantum setting are rather scanty. In this paper, we give more improved polynomial-time quantum distinguishers on Type-1 GFS in quantum chosen-plaintext attack (qCPA) setting and quantum chosen-ciphertext attack (qCCA) setting. In qCPA setting, we give new quantum polynomial-time distinguishers on $(3d-3)$-round Type-1 GFS with branches $d\geq3$, which gain $d-2$ more rounds than the previous distinguishers. Hence, we could get better key-recovery attacks, whose time complexities gain a factor of $2^{\frac{(d-2)n}{2}}$. In qCCA setting, we get $(3d-3)$-round quantum distinguishers on Type-1 GFS, which gain $d-1$ more rounds than the previous distinguishers. In addition, we give some quantum attacks on CAST-256 block cipher. We find 12-round and 13-round polynomial-time quantum distinguishers in qCPA and qCCA settings, respectively, while the best previous one is only 7 rounds. Hence, we could derive quantum key-recovery attack on 19-round CAST-256. While the best previous quantum key-recovery attack is on 16 rounds. When comparing our quantum attacks with classical attacks, our result also reaches 16 rounds on CAST-256 with 128-bit key under a competitive complexity

(Quantum) Collision Attacks on Reduced Simpira v2

Simpira v2 is an AES-based permutation proposed by Gueron and Mouha at ASIACRYPT 2016. In this paper, we build an improved MILP model to count the differential and linear active Sboxes for Simpira v2, which achieves tighter bounds of the minimum number of active Sboxes for a few versions of Simpira v2. Then, based on the new model, we find some new truncated differentials for Simpira v2 and give a series (quantum) collision attacks on two versions of reduced Simpira v2

(Quantum) Collision Attacks on Reduced Simpira v2

Simpira v2 is an AES-based permutation proposed by Gueron and Mouha at ASIACRYPT 2016. In this paper, we build an improved MILP model to count the differential and linear active Sboxes for Simpira v2, which achieves tighter bounds of the minimum number of active Sboxes for a few versions of Simpira v2. Then, based on the new model, we find some new truncated differentials for Simpira v2 and give a series (quantum) collision attacks on two versions of reduced Simpira v2

3D geometry‐based UAV to vehicle multiple‐input multiple‐output channel model incorporating Unmanned aerial vehicle heaving motion

Abstract Unmanned aerial vehicles (UAVs) play a vital role in the beyond fifth‐generation (B5G) and sixth‐generation (6G) wireless communication scenarios. This paper proposes a non‐stationary three‐dimensional (3D) geometry‐based multiple‐input multiple‐output channel model for UAV to vehicle (U2V) communications considering UAV heaving motion. The proposed model incorporates the effects of UAV heaving along with the rotation, acceleration, and 3D velocity variation for matching the realistic U2V communication scenarios. The computation methods for time variant channel parameters such as Doppler frequencies, angle of arrival, and angle of departure are given and analysed. The theoretical and statistical properties, including spatial temporal correlation function, TCF, level crossing rate, average fade duration, and Doppler power spectral density are derived and analysed aiming to evaluate the proposed model. Simulation results show that the output statistical characteristics agree with the hypothetical and simulated outcomes, which shows the validity of both the channel model and theoretical derivations. The cover image is based on the Research Article 3D geometry‐based UAV to vehicle multiple‐input multiple‐output channel model incorporating Unmanned aerial vehicle heaving motion by Naeem Ahmed et al., https://doi.org/10.1049/mia2.1239

Fracture at the two-dimensional limit

Abstract More than a century ago, A.A. Griffith published the seminal paper establishing the foundational framework for fracture mechanics. The elegant theory creatively introduced the concepts of elastic energy and surface energy to the science of fracture, and solved the problem of brittle fracture of glass materials. Many subsequent milestone studies in fracture mechanics were motivated by the real problems encountered in different materials. The emergence of two-dimensional (2D) materials provides an exciting opportunity to examine fracture processes at the 2D limit. An important question to be addressed is whether the classic Griffith theory is still applicable to 2D materials. Therefore, recent progress in both experimental and theoretical studies of fracture of 2D materials will be briefly reviewed, with new developments and discoveries in relevant techniques and theories highlighted. Given the early stage of exploring fracture behaviors in 2D materials, more emphasis will be placed on challenges and opportunities for this budding field. Graphical abstrac