Attacks in Stream Ciphers: A Survey

Nowadays there are different types of attacks in block and stream ciphers. In this work we will present some of the most used attacks on stream ciphers. We will present the newest techniques with an example of usage in a cipher, explain and comment. Previous we will explain the difference between the block ciphers and stream ciphers

A new class of irreducible pentanomials for polynomial-based multipliers in binary fields

We introduce a new class of irreducible pentanomials over $\mathbb{F}_2$ of the form $f(x) = x^{2b+c} + x^{b+c} + x^b + x^c + 1$. Let $m=2b+c$ and use $f$ to define the finite field extension of degree $m$. We give the exact number of operations required for computing the reduction modulo $f$. We also provide a multiplier based on Karatsuba algorithm in $\mathbb{F}_2[x]$ combined with our reduction process. We give the total cost of the multiplier and found that the bit-parallel multiplier defined by this new class of polynomials has improved XOR and AND complexity. Our multiplier has comparable time delay when compared to other multipliers based on Karatsuba algorithm

Statically Aggregate Verifiable Random Functions and Application to E-Lottery

Cohen, Goldwasser, and Vaikuntanathan (TCC\u2715) introduced the concept of aggregate pseudo-random functions (PRFs), which allow efficiently computing the aggregate of PRF values over exponential-sized sets. In this paper, we explore the aggregation augmentation on verifiable random function (VRFs), introduced by Micali, Rabin and Vadhan (FOCS\u2799), as well as its application to e-lottery schemes. We introduce the notion of static aggregate verifiable random functions (Agg-VRFs), which perform aggregation for VRFs in a static setting. Our contributions can be summarized as follows: (1) we define static aggregate VRFs, which allow the efficient aggregation of VRF values and the corresponding proofs over super-polynomially large sets; (2) we present a static Agg-VRF construction over bit-fixing sets with respect to product aggregation based on the q-decisional Diffie-Hellman exponent assumption; (3) we test the performance of our static Agg-VRFs instantiation in comparison to a standard (non-aggregate) VRF in terms of costing time for the aggregation and verification processes, which shows that Agg-VRFs lower considerably the timing of verification of big sets; and (4) by employing Agg-VRFs, we propose an improved e-lottery scheme based on the framework of Chow et al.\u27s VRF-based e-lottery proposal (ICCSA\u2705). We evaluate the performance of Chow et al.\u27s e-lottery scheme and our improved scheme, and the latter shows a significant improvement in the efficiency of generating the winning number and the player verification

Practical and Provably Secure Distributed Aggregation: Verifiable Additive Homomorphic Secret Sharing

Often clients (e.g., sensors, organizations) need to outsource joint computations that are based on some joint inputs to external untrusted servers. These computations often rely on the aggregation of data collected from multiple clients, while the clients want to guarantee that the results are correct and, thus, an output that can be publicly verified is required. However, important security and privacy challenges are raised, since clients may hold sensitive information. In this paper, we propose an approach, called verifiable additive homomorphic secret sharing (VAHSS), to achieve practical and provably secure aggregation of data, while allowing for the clients to protect their secret data and providing public verifiability i.e., everyone should be able to verify the correctness of the computed result. We propose three VAHSS constructions by combining an additive homomorphic secret sharing (HSS) scheme, for computing the sum of the clients\u27 secret inputs, and three different methods for achieving public verifiability, namely: (i) homomorphic collision-resistant hash functions; (ii) linear homomorphic signatures; as well as (iii) a threshold RSA signature scheme. In all three constructions, we provide a detailed correctness, security, and verifiability analysis and detailed experimental evaluations. Our results demonstrate the efficiency of our proposed constructions, especially from the client side

Multi-Armed SPHINCS+

Hash-based signatures are a type of Digital Signature Algorithms that are positioned as one of the most solid quantum-resistant constructions. As an example SPHINCS+, has been selected as a standard during the NIST Post-Quantum Cryptography competition. However, hash-based signatures suffer from two main drawbacks: signature size and slow signing process. In this work, we give a solution to the latter when it is used in a mobile device. We take advantage of the fact that hash-based signatures are highly parallelizable. More precisely, we provide an implementation of SPHINCS+ on the Snapdragon 865 Mobile Platform taking advantage of its eight CPUs and their vector extensions. Our implementation shows that it is possible to have a speed-up of 15 times when compared to a purely sequential and non-vectorized implementation. Furthermore, we evaluate the performance impact of side-channel protection using vector extensions in the SPHINCS+ version based on SHAKE

Fast and Frobenius: Rational Isogeny Evaluation over Finite Fields

Consider the problem of efficiently evaluating isogenies $\phi: E \to E/H$ of elliptic curves over a finite field $\mathbb{F}_q$, where the kernel $H = \langle G\rangle$ is a cyclic group of odd (prime) order: given $E$, $G$, and a point (or several points) $P$ on $E$, we want to compute $\phi(P)$. This problem is at the heart of efficient implementations of group-action- and isogeny-based post-quantum cryptosystems such as CSIDH. Algorithms based on V{\'e}lu's formulae give an efficient solution to this problem when the kernel generator $G$ is defined over $\mathbb{F}_q$. However, for general isogenies, $G$ is only defined over some extension $\mathbb{F}_{q^k}$, even though $\langle G\rangle$ as a whole (and thus $\phi$) is defined over the base field $\mathbb{F}_q$; and the performance of V{\'e}lu-style algorithms degrades rapidly as $k$ grows. In this article we revisit the isogeny-evaluation problem with a special focus on the case where $1 \le k \le 12$. We improve V{\'e}lu-style isogeny evaluation for many cases where $k = 1$ using special addition chains, and combine this with the action of Galois to give greater improvements when $k > 1$

Concrete quantum cryptanalysis of binary elliptic curves

This paper analyzes and optimizes quantum circuits for computing discrete logarithms on binary elliptic curves, including reversible circuits for fixed-base-point scalar multiplication and the full stack of relevant subroutines. The main optimization target is the size of the quantum computer, i.e., the number of logical qubits required, as this appears to be the main obstacle to implementing Shor’s polynomial-time discrete-logarithm algorithm. The secondary optimization target is the number of logical Toffoli gates. For an elliptic curve over a field of 2n elements, this paper reduces the number of qubits to 7n + ⌊log2 (n)⌋ + 9. At the same time this paper reduces the number of Toffoli gates to 48n3 + 8nlog2(3)+1 + 352n2 log2 (n) + 512n2 + O(nlog2(3)) with double-and-add scalar multiplication, and a logarithmic factor smaller with fixed-window scalar multiplication. The number of CNOT gates is also O(n3). Exact gate counts are given for various sizes of elliptic curves currently used for cryptography

Concrete quantum cryptanalysis of binary elliptic curves

This paper analyzes and optimizes quantum circuits for computing discrete logarithms on binary elliptic curves, including reversible circuits for fixed-base-point scalar multiplication and the full stack of relevant subroutines. The main optimization target is the size of the quantum computer, i.e., the number of logical qubits required, as this appears to be the main obstacle to implementing Shor’s polynomial-time discrete-logarithm algorithm. The secondary optimization target is the number of logical Toffoli gates. For an elliptic curve over a field of 2n elements, this paper reduces the number of qubits to 7n + ⌊log2 (n)⌋ + 9. At the same time this paper reduces the number of Toffoli gates to 48n3 + 8nlog2(3)+1 + 352n2 log2 (n) + 512n2 + O(nlog2(3)) with double-and-add scalar multiplication, and a logarithmic factor smaller with fixed-window scalar multiplication. The number of CNOT gates is also O(n3). Exact gate counts are given for various sizes of elliptic curves currently used for cryptography

Efficient supersingularity testing over F_p and CSIDH key validation

International audienceMany public-key cryptographic protocols, notably non-interactive key exchange (NIKE), require incoming public keys to be validated to mitigate some adaptive attacks. In CSIDH, an isogeny-based post-quantum NIKE, a key is deemed legitimate if the given Montgomery coefficient specifies a supersingular elliptic curve over the prime field. In this work, we survey the current supersingularity tests used for CSIDH key validation, and implement and measure two new alternative algorithms. Our implementation shows that we can determine supersingularity substantially faster, and using less memory, than the state-of-the-art

Elaboración de diez Bitters (amargos) para la creación de recetas de cocteles de autor

El presente proyecto de intervención tiene como objetivo elaborar diez bitters (amargos) para la creación de recetas de cocteles de autor. Para ello se trabajó con hojas, cortezas y raíces de doce plantas de origen ecuatoriano tales como: Albahaca (ocimum basilicum), Canela (cinnamomum verum), Cedrón (aloysia citrodora), Eucalipto (eucalyptus), Flor de Jamaica (hibiscus sabdariffa), Hierba Buena (mentha spicata), Hierba Luisa (cymbopogon citratus), Jengibre (zingiber officinale), Menta (mentha piperita), Naranja (citrus x sinensis), Naranjilla (solanum quitoense), Romero (salvia rosmarinus), las cuales fueron seleccionadas con base en sus propiedades organolépticas. El método experimental utilizado, permitió obtener amargos con un equilibrio en sabor, aroma y color, para ello se utilizó la técnica de maceración en una bebida espirituosa (vodka), durante treinta días, se obtuvieron bitters de alta calidad los cuales fueron aplicados en la creación de veinte cocteles de autor y posteriormente la elaboración de un recetario. Los resultados indicaron la viabilidad en la fabricación de bitters artesanales, con estándares de alta calidad a un bajo costo de producción. El amargo fabricado tuvo una proporción excelente dado que aportó equilibrio a la elaboración de todos los cocteles propuestos en este trabajo. Finalmente, los bitters elaborados cumplieron el propósito de brindar equilibrio a cada propuesta de coctel de autor en el cual fue aplicado, lo cual brindó una ponderación elevada en todos los parámetros propuestos. Palabras Clave: Bebida espirituosa, Bitter, Coctel, Maceración, Parámetro.This intervention project aims to produce ten bitters (bitters) for the creation of signature cocktail recipes. For this, we worked with leaves, bark and roots of twelve plants of Ecuadorian origin such as: Basil (ocimum basilicum), Cinnamon (cinnamomum verum), Cedrón (aloysia citrodora), Eucalyptus (eucalyptus), Flor de Hibiscus (hibiscus sabdariffa), Peppermint (mentha spicata), Lemongrass (cymbopogon citratus), Ginger (zingiber officinale), Peppermint (mentha piperita), Orange (citrus x sinensis), Naranjilla (solanum quitoense), Romero (salvia rosmarinus), which were selected based on their organoleptic properties. The experimental method used, allowed to obtain bitters with a balance in flavor, aroma and color, for it used the technique of maceration in a spirit drink (vodka) for thirty days, obtained high quality bitters which were applied in the creation of twenty signature cocktails and later the preparation of a recipe book. The results indicated viability in the manufacture of artisanal bitters, with high quality standards at a low production cost. The manufactured bitter had an excellent proportion since it provided balance to the elaboration of all the cocktails proposed in this work. Finally, the Elaborated bitters fulfilled the purpose of providing balance to each cocktail proposal of author in which it was applied, which provided a high weighting in all the proposed parameters. Keywords: Spirit drink, Bitter, Cocktail, Maceration, Parameter.Licenciado en Gastronomía y Servicio de Alimentos y BebidasCuenc