89,837 research outputs found
The Brauer-Manin Obstruction and Sha[2].
No full textWe discuss the Brauer-Manin obstruction on del Pezzo surfaces of degree 4. We outline a detailed algorithm for computing the obstruction and provide associated programs in magma. This is illustrated with the computation of an example with an irreducible cubic factor in the singular locus of the defining pencil of quadrics (in contrast to previous examples, which had at worst quadratic irreducible factors). We exploit the relationship with the Tate-Shafarevich group to give new types of examples of Sha[2], for families of curves of genus 2 of the form y^2 = f(x), where f(x) is a quintic containing an irreducible cubic factor
Maximizing the Potential of Custom RISC-V Vector Extensions for Speeding up SHA-3 Hash Functions
No full textSHA-3 is considered to be one of the most secure standardized hash functions. It relies on the Keccak-f[1 600] permutation, which operates on an internal state of 1 600 bits, mostly represented as a 5 x 5 x 64-bit matrix. While existing implementations process the state sequentially in chunks of typically 32 or 64 bits, the Keccak-f[1 600] permutation can benefit a lot from speedup through parallelization. This paper is the first to explore the full potential of parallelization of Keccak-f[1 600] in RISC-V based processors through custom vector extensions on 32-bit and 64-bit architectures. We analyze the Keccak permutation, composed of five different step mappings, and propose ten custom vector instructions to speed up the computation. We realize these extensions in a SIMD processor described in System Verilog. We compare the performance of our designs to existing architectures based on vectorized application-specific instruction set processors (ASIP). We show that our designs outperform all related work in throughput due to our carefully selected custom vector instructions.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Cyber Securit
Uma solução de autenticação fim a fim para o LDP (Label Distribution Protocol)
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Ciência da Computação.Este trabalho propõe uma solução de autenticação para o protocolo LDP (Label Distribution Protocol) que tem por objetivo autenticar, em um escopo fim a fim, o estabelecimento de um LSP (Label Switching Path) entre um LSR (Label Switching Router) de Ingresso e o seu respectivo LSR de Egresso. Objetiva-se suprir a deficiência do protocolo LDP de não possuir um mecanismo de autenticação fim a fim definido, aplicável entre LSRs não-adjacentes. Conforme foi verificado pelo levantamento de trabalhos correlatos, atualmente é desconhecida uma solução de autenticação semelhante, que efetivamente atenda o propósito de autenticar num escopo fim a fim, o estabelecimento de LSPs no protocolo LDP. Dessa forma a solução deste trabalho é inédita no seu escopo de aplicação. A solução foi planejada para ambientes onde LSPs atravessam múltiplos domínios externos, não confiáveis entre si, e que por isso necessitam de um mecanismo de autenticação durante o estabelecimento dos LSPs. A solução faz uso de um mecanismo de autenticação, baseado em criptografia assimétrica (chave pública e privada), anexado a cada mensagem LDP. Este mecanismo possibilita ao LSR receptor verificar e autenticar o originador da mensagem LDP. Adicionalmente a solução provê integridade de dados através de um mecanismo de resumo de mensagens (hash) e também protege contra ataques de repetição através da inserção de um nonce às mensagens LDP
Exploiting an HMAC-SHA-1 optimization to speed up PBKDF2
No full textPBKDF2 is a well-known password-based key derivation function. In order to slow attackers down, PBKDF2 introduces CPU-intensive operations based on an iterated pseudorandom function (in our case HMAC-SHA-1). If we are able to speed up a SHA-1 or an HMAC implementation, we are able to speed up PBKDF2-HMAC-SHA-1. This means that a performance improvement might be exploited by regular users and attackers. Interestingly, FIPS 198-1 suggests that it is possible to precompute first message block of a keyed hash function only once, store such a value and use it each time is needed. Therefore the computation of first message block does not contribute to slowing attackers down, thus making the computation of second message block crucial. In this paper we focus on the latter, investigating the possibility to avoid part of the HMAC-SHA-1 operations. We show that some CPU-intensive operations may be replaced with a set of equivalent, but less onerous, instructions. We identify useless XOR operations exploiting and extending Intel optimizations, and applying the Boyar-Peralta heuristic. In addition, we provide an alternative method to compute the SHA-1 message scheduling function and explain why attackers might exploit these findings to speed up a brute force attack against PBKDF2
SHA2 and SHA-3 accelerator design in a 7 nm technology within the European Processor Initiative
No full textThis paper proposes the architecture of the hash accelerator, developed in the framework of the European Processor Initiative. The proposed circuit supports all the SHA2 and SHA-3 operative modes and is to be one of the hardware cryptographic accelerators within the crypto-tile of the European Processor Initiative. The accelerator has been verified on a Stratix IV FPGA and then synthesised on the Artisan 7 nanometres TSMC silicon technology, obtaining throughputs higher than 50 Gbps for the SHA2 and 230 Gbps for the SHA-3, with complexity ranging from 15 to about 30 kGE and estimated power dissipation of about 13 (SHA2) to 26 (SHA-3) mW (supply voltage 0.75 V). The proposed design demonstrates absolute performances beyond the state-of-the-art and efficiency aligned with it. One of the main contributions is that this is the first SHA-2 SHA-3 accelerator synthesised on such advanced technology
Sistem Tanda Tangan Digital Menggunakan SHA-3 dan ECDSA
No full textThis research aims to implement an information security system for electronic documents using electronic signatures based on ECDSA (Elliptic Curve Digital Signature Algorithm) and SHA-3 (Secure Hash Algorithm 3) algorithms. This research was conducted to answer questions about the security and integrity protection of digital documents in today's digital age. The research method used is a randomized controlled experiment testing the effectiveness of a security system implemented in a simulated environment. The data obtained from this experiment were statistically analyzed with valid and reliable results. Research results show that implementing a security system with digital signatures based on ECDSA and SHA-3 effectively protects the security and integrity of digital documents. The ECDSA algorithm ensures the legitimacy and authentication of digital documents through a digital signature process using private and public keys. The SHA-3 algorithm is used as a strong hashing algorithm to compute hashes of digital documents to ensure data integrity. The results show that a security system implemented using digital signatures based on ECDSA and SHA-3 can provide a high level of security in protecting digital documents. Prevent unauthorized changes and tampering.Penelitian ini bertujuan untuk mengimplementasikan sistem keamanan informasi dalam dokumen digital menggunakan digital signature berbasis algoritma ECDSA (Elliptic Curve Digital Signature Algorithm) dan SHA-3 (Secure Hash Algorithm 3). Penelitian ini dilakukan untuk menjawab permasalahan mengenai perlindungan keamanan dan integritas dokumen digital dalam era digital saat ini. Metode penelitian yang digunakan adalah eksperimen kontrol acak, di mana sistem keamanan yang diimplementasikan dalam lingkungan simulasi diuji untuk mengukur efektivitasnya. Data yang diperoleh dari eksperimen ini dianalisis secara statistik untuk mendapatkan hasil yang valid dan dapat diandalkan. Hasil penelitian menunjukkan bahwa implementasi sistem keamanan menggunakan digital signature berbasis ECDSA dan SHA-3 efektif dalam melindungi keamanan dan integritas dokumen digital. Algoritma ECDSA memberikan keabsahan dan otentikasi dokumen digital melalui proses tanda tangan digital yang menggunakan kunci privat dan publik. Algoritma SHA-3, sebagai algoritma hash yang kuat, digunakan untuk menghitung hash dokumen digital guna memastikan integritas data.Hasil penelitian menunjukan bahwa sistem keamanan yang diimplementasikan dengan menggunakan digital signature berbasis ECDSA dan SHA-3 mampu memberikan tingkat keamanan yang tinggi dalam melindungi dokumen digital dari perubahan yang tidak sah dan pemalsuan
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
The Brauer-Manin obstruction and Sha[2]
No full textThe authors of this paper discuss the Brauer–Manin obstruction on del Pezzo surfaces of degree 4. They outline a detailed algorithm for computing the obstruction, and provide associated programs in MAGMA. This is illustrated with the computation of an example with an irreducible cubic factor in the singular locus of the defining pencil of quadrics (in contrast to previous examples, which had at worst quadratic irreducible factors). The relationship with the Tate–Shafarevich group is exploited to give new types of examples of Sha[2], for families of curves of genus 2 of the form y2 = f(x), where f(x) is a quintic containing an irreducible cubic factor.The authors of this paper discuss the Brauer–Manin obstruction on del Pezzo surfaces of degree 4. They outline a detailed algorithm for computing the obstruction, and provide associated programs in MAGMA. This is illustrated with the computation of an example with an irreducible cubic factor in the singular locus of the defining pencil of quadrics (in contrast to previous examples, which had at worst quadratic irreducible factors). The relationship with the Tate–Shafarevich group is exploited to give new types of examples of Sha[2], for families of curves of genus 2 of the form y2 = f(x), where f(x) is a quintic containing an irreducible cubic factor
Chaining Optimization Methodology: A New SHA-3 Implementation on Low-End Microcontrollers
No full textSince the Keccak algorithm was selected by the US National Institute of Standards and Technology (NIST) as the standard SHA-3 hash algorithm for replacing the currently used SHA-2 algorithm in 2015, various optimization methods have been studied in parallel and hardware environments. However, in a software environment, the SHA-3 algorithm is much slower than the existing SHA-2 family; therefore, the use of the SHA-3 algorithm is low in a limited environment using embedded devices such as a Wireless Sensor Networks (WSN) enviornment. In this article, we propose a software optimization method that can be used generally to break through the speed limit of SHA-3. We combine the θ, π, and ρ processes into one, reducing memory access to the internal state more efficiently than conventional software methods. In addition, we present a new SHA-3 implementation for the proposed method in the most constrained environment, the 8-bit AVR microcontroller. This new implementation method, which we call the chaining optimization methodology, implicitly performs the π process of the f-function while minimizing memory access to the internal state of SHA-3. Through this, it achieves up to 26.1% performance improvement compared to the previous implementation in an AVR microcontroller and reduces the performance gap with the SHA-2 family to the maximum. Finally, we apply our SHA-3 implementation in Hash_Deterministic Random Bit Generator (Hash_DRBG), one of the upper algorithms of a hash function, to prove the applicability of our chaining optimization methodology on 8-bit AVR MCUs
[Newspaper Clipping: Author Claims Evidence of Second JFK Assassin #1]
No full textNewspaper article titled "Author Claims Evidence of Second JFK Assassin." The article states that author Richard J. Whalen concluded "that there is circumstantial evidence to support the theory of a second assassin in the shooting of President John F. Kennedy.
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