Neon NTT: Faster Dilithium, Kyber, and Saber on Cortex-A72 and Apple M1

We present new speed records on the Armv8-A architecture for the latticebased schemes Dilithium, Kyber, and Saber. The core novelty in this paper is the combination of Montgomery multiplication and Barrett reduction resulting in “Barrett multiplication” which allows particularly efficient modular one-known-factor multiplication using the Armv8-A Neon vector instructions. These novel techniques combined with fast two-unknown-factor Montgomery multiplication, Barrett reduction sequences, and interleaved multi-stage butterflies result in significantly faster code. We also introduce “asymmetric multiplication” which is an improved technique for caching the results of the incomplete NTT, used e.g. for matrix-to-vector polynomial multiplication. Our implementations target the Arm Cortex-A72 CPU, on which our speed is 1.7× that of the state-of-the-art matrix-to-vector polynomial multiplication in kyber768 [Nguyen–Gaj 2021]. For Saber, NTTs are far superior to Toom–Cook multiplication on the Armv8-A architecture, outrunning the matrix-to-vector polynomial multiplication by 2.0×. On the Apple M1, our matrix-vector products run 2.1× and 1.9× faster for Kyber and Saber respectively.

Minimal indices and minimal bases via filtrations

A new way to formulate the notions of minimal basis and minimal indices is developed in this paper, based on the concept of a filtration of a vector space. The goal is to provide useful new tools for working with these important concepts, as well as to gain deeper insight into their fundamental nature. This approach also readily reveals a strong minimality property of minimal indices, from which follows a characterization of the vector polynomial bases in rational vector spaces. The effectiveness of this new formulation is further illustrated by proving several fundamental properties: the invariance of the minimal indices of a matrix polynomial under field extension, the direct sum property of minimal indices, the polynomial linear combination property, and the predictable degree property.

Predefined-time vector-polynomial-based synchronization among a group of chaotic systems and its application in secure information transmission

<abstract><p>This article aims to improve the security and timeliness of chaotic synchronization scheme in chaotic secure information transmission. Firstly, a novel nonlinear synchronization scheme among multiple chaotic systems is defined based on vector polynomial to improve the complexity of the carrier signal, and then to enhance the attack resistance of the communication scheme. Secondly, a more flexible and accurate synchronization control technology is proposed so that the above vector-polynomial-based chaotic synchronization can be realized within a time that is predefined as a tunable control parameter. Subsequently, the theoretical derivation is carried out to prove the synchronization time in the above-mentioned synchronization control scheme can be set independently without being affected by the initial conditions or other control parameters. Finally, several simulation experiments on secure information transmission are presented to verify the efficiency and superiority of the designed chaotic synchronization scheme and synchronization control technology.</p></abstract>

Properties of triple error orbits G and their invariants in Bose – Chaudhuri – Hocquenghem codes C7

This work is the further development of the theory of norms of syndromes: the theory of polynomial invariants of G-orbits of errors expands with the group G of automorphisms of binary cyclic BCH codes obtained by joining the degrees of cyclotomic permutation to the group Γ and practically exhausting the group of automorphisms of BCH codes. It is determined that polynomial invariants, like the norms of syndromes, have a scalar character and are one-to-one characteristics of their orbits for BCH codes with a constructive distance of five. The paper introduces the corresponding vector polynomial invariants for primitive cyclic BCH codes with a constructive distance of seven, next to the norms of the syndromes that are already vector quantities; the basic properties of the vector polynomial invariants are investigated. It is established that the property of mutual unambiguity is violated: there are G-orbit-isomers, which are different, but have the same vector polynomial invariants. It is substantiated and demonstrated by examples that this circumstance greatly complicates error decoding algorithms based on polynomial invariants

A Bayes Estimator of Parameters of Nonlinear Dynamic Systems

A new multipolynomial approximations algorithm (the MPA algorithm) is proposed for estimating the state vectorθof virtually any dynamical (evolutionary) system. The input of the algorithm consists of discrete-time observationsY. An adjustment of the algorithm is required to the generation of arrays of random sequences of state vectors and observations scalars corresponding to a given sequence of time instants. The distributions of the random factors (vectors of the initial states and random perturbations of the system, scalars of random observational errors) can be arbitrary but have to be prescribed beforehand. The output of the algorithm is a vector polynomial series with respect to products of nonnegative integer powers of the results of real observations or some functions of these results. The sum of the powers does not exceed some given integerd. The series is a vector polynomial approximation of the vectorE(θ∣Y), which is the conditional expectation of the vector under evaluation (or given functions of the components of that vector). The vector coefficients of the polynomial series are constructed in such a way that the approximation errors uniformly tend to zero as the integerdincreases. These coefficients are found by the Monte-Carlo method and a process of recurrent calculations that do not require matrix inversion.

Some elliptic balls which avoid a Nyquist set in ℂn+1

SynopsisConditions are obtained for certain elliptic balls in ℂn+1 to have empty intersection with the Nyquist set of a vector polynomial G(z). Such conditions are shown to yield explicit criteria for the existence of periodic solutions of non-autonomous scalar differential equations of the form A* G(D)y = p.

Inclusion conditions for Hurwitzian and Schur sets in

A condition of frequency domain type on the vector polynomial G(z) is obtained which is both necessary and sufficient for the Hurwitzian set of G(z) to include the special Hurwitzian set , where E(z) = col (1, z, …, zn). This result is extended to Hurwitzian sets arising from scalar delay-differential equations. Analogous conditions are also given for each of the inclusions where denotes the Schur set of G(z).