Point compression for the trace zero subgroup over a small degree extension field

Using Semaev's summation polynomials, we derive a new equation for the $\mathbb{F}_q$-rational points of the trace zero variety of an elliptic curve defined over $\mathbb{F}_q$. Using this equation, we produce an optimal-size representation for such points. Our representation is compatible with scalar multiplication. We give a point compression algorithm to compute the representation and a decompression algorithm to recover the original point (up to some small ambiguity). The algorithms are efficient for trace zero varieties coming from small degree extension fields. We give explicit equations and discuss in detail the practically relevant cases of cubic and quintic field extensions.Comment: 23 pages, to appear in Designs, Codes and Cryptograph

Optimizing scalar multiplication for koblitz curves using hybrid FPGAs

Elliptic curve cryptography (ECC) is a type of public-key cryptosystem which uses the additive group of points on a nonsingular elliptic curve as a cryptographic medium. Koblitz curves are special elliptic curves that have unique properties which allow scalar multiplication, the bottleneck operation in most ECC cryptosystems, to be performed very efficiently. Optimizing the scalar multiplication operation on Koblitz curves is an active area of research with many proposed algorithms for FPGA and software implementations. As of yet little to no research has been reported on using the capabilities of hybrid FPGAs, such as the Xilinx Virtex-4 FX series, which would allow for the design of a more flexible single-chip system that performs scalar multiplication and is not constrained by high communication costs between hardware and software. While the results obtained in this thesis were competitive with many other FPGA implementations, the most recent research efforts have produced significantly faster FPGA based systems. These systems were created by utilizing new and interesting approaches to improve the runtime of performing scalar multiplication on Koblitz curves and thus significantly outperformed the results obtained in this thesis. However, this thesis also functioned as a comparative study of the usage of different basis representations and proved that strict polynomial basis approaches can compete with strict normal basis implementations when performing scalar multiplication on Koblitz curves

Efficient and Secure ECDSA Algorithm and its Applications: A Survey

Public-key cryptography algorithms, especially elliptic curve cryptography (ECC)and elliptic curve digital signature algorithm (ECDSA) have been attracting attention frommany researchers in different institutions because these algorithms provide security andhigh performance when being used in many areas such as electronic-healthcare, electronicbanking,electronic-commerce, electronic-vehicular, and electronic-governance. These algorithmsheighten security against various attacks and the same time improve performanceto obtain efficiencies (time, memory, reduced computation complexity, and energy saving)in an environment of constrained source and large systems. This paper presents detailedand a comprehensive survey of an update of the ECDSA algorithm in terms of performance,security, and applications

Efficient software implementation of elliptic curves and bilinear pairings

Orientador: Júlio César Lopez HernándezTese (doutorado) - Universidade Estadual de Campinas, Instituto de ComputaçãoResumo: O advento da criptografia assimétrica ou de chave pública possibilitou a aplicação de criptografia em novos cenários, como assinaturas digitais e comércio eletrônico, tornando-a componente vital para o fornecimento de confidencialidade e autenticação em meios de comunicação. Dentre os métodos mais eficientes de criptografia assimétrica, a criptografia de curvas elípticas destaca-se pelos baixos requisitos de armazenamento para chaves e custo computacional para execução. A descoberta relativamente recente da criptografia baseada em emparelhamentos bilineares sobre curvas elípticas permitiu ainda sua flexibilização e a construção de sistemas criptográficos com propriedades inovadoras, como sistemas baseados em identidades e suas variantes. Porém, o custo computacional de criptossistemas baseados em emparelhamentos ainda permanece significativamente maior do que os assimétricos tradicionais, representando um obstáculo para sua adoção, especialmente em dispositivos com recursos limitados. As contribuições deste trabalho objetivam aprimorar o desempenho de criptossistemas baseados em curvas elípticas e emparelhamentos bilineares e consistem em: (i) implementação eficiente de corpos binários em arquiteturas embutidas de 8 bits (microcontroladores presentes em sensores sem fio); (ii) formulação eficiente de aritmética em corpos binários para conjuntos vetoriais de arquiteturas de 64 bits e famílias mais recentes de processadores desktop dotadas de suporte nativo à multiplicação em corpos binários; (iii) técnicas para implementação serial e paralela de curvas elípticas binárias e emparelhamentos bilineares simétricos e assimétricos definidos sobre corpos primos ou binários. Estas contribuições permitiram obter significativos ganhos de desempenho e, conseqüentemente, uma série de recordes de velocidade para o cálculo de diversos algoritmos criptográficos relevantes em arquiteturas modernas que vão de sistemas embarcados de 8 bits a processadores com 8 coresAbstract: The development of asymmetric or public key cryptography made possible new applications of cryptography such as digital signatures and electronic commerce. Cryptography is now a vital component for providing confidentiality and authentication in communication infra-structures. Elliptic Curve Cryptography is among the most efficient public-key methods because of its low storage and computational requirements. The relatively recent advent of Pairing-Based Cryptography allowed the further construction of flexible and innovative cryptographic solutions like Identity-Based Cryptography and variants. However, the computational cost of pairing-based cryptosystems remains significantly higher than traditional public key cryptosystems and thus an important obstacle for adoption, specially in resource-constrained devices. The main contributions of this work aim to improve the performance of curve-based cryptosystems, consisting of: (i) efficient implementation of binary fields in 8-bit microcontrollers embedded in sensor network nodes; (ii) efficient formulation of binary field arithmetic in terms of vector instructions present in 64-bit architectures, and on the recently-introduced native support for binary field multiplication in the latest Intel microarchitecture families; (iii) techniques for serial and parallel implementation of binary elliptic curves and symmetric and asymmetric pairings defined over prime and binary fields. These contributions produced important performance improvements and, consequently, several speed records for computing relevant cryptographic algorithms in modern computer architectures ranging from embedded 8-bit microcontrollers to 8-core processorsDoutoradoCiência da ComputaçãoDoutor em Ciência da Computaçã

Cryptographic Pairings: Efficiency and DLP security

This thesis studies two important aspects of the use of pairings in cryptography, efficient algorithms and security. Pairings are very useful tools in cryptography, originally used for the cryptanalysis of elliptic curve cryptography, they are now used in key exchange protocols, signature schemes and Identity-based cryptography. This thesis comprises of two parts: Security and Efficient Algorithms. In Part I: Security, the security of pairing-based protocols is considered, with a thorough examination of the Discrete Logarithm Problem (DLP) as it occurs in PBC. Results on the relationship between the two instances of the DLP will be presented along with a discussion about the appropriate selection of parameters to ensure particular security level. In Part II: Efficient Algorithms, some of the computational issues which arise when using pairings in cryptography are addressed. Pairings can be computationally expensive, so the Pairing-Based Cryptography (PBC) research community is constantly striving to find computational improvements for all aspects of protocols using pairings. The improvements given in this section contribute towards more efficient methods for the computation of pairings, and increase the efficiency of operations necessary in some pairing-based protocol

Koblitz curves over quadratic fields

In this work, we retake an old idea that Koblitz presented in his landmark paper, where he suggested the possibility of defining anomalous elliptic curves over the base field F4. We present a careful implementation of the base and quadratic field arithmetic required for computing the scalar multiplication operation in such curves. We also introduce two ordinary Koblitz-like elliptic curves defined over F4 that are equipped with efficient endomorphisms. To the best of our knowledge these endomorphisms have not been reported before. In order to achieve a fast reduction procedure, we adopted a redundant trinomial strategy that embeds elements of the field F4^m, with m a prime number, into a ring of higher order defined by an almost irreducible trinomial. We also present a number of techniques that allow us to take full advantage of the native vector instructions of high-end microprocessors. Our software library achieves the fastest timings reported for the computation of the timing-protected scalar multiplication on Koblitz curves, and competitive timings with respect to the speed records established recently in the computation of the scalar multiplication over binary and prime fields

Point Counting On Genus 2 Curves

For cryptographic purposes, counting points on the jacobian variety of a given hyperelliptic curve is of great importance. There has been several approaches to obtain the cardinality of such a group, specially for hyperelliptic curves of genus 2. The best known algorithm for counting points on genus 2 curves over prime fields of large characteristic is a variant of Schoof’s genus 1 algorithm. Following a recent work of Gaudry and Schost, we show how to speed up the current state of the art genus 2 point counting algorithm by proposing various computational improvements to its basic arithmetical ingredients

Identity based cryptography from bilinear pairings

This report contains an overview of two related areas of research in cryptography which have been prolific in significant advances in recent years. The first of these areas is pairing based cryptography. Bilinear pairings over elliptic curves were initially used as formal mathematical tools and later as cryptanalysis tools that rendered supersingular curves insecure. In recent years, bilinear pairings have been used to construct many cryptographic schemes. The second area covered by this report is identity based cryptography. Digital certificates are a fundamental part of public key cryptography, as one needs a secure way of associating an agent’s identity with a random (meaningless) public key. In identity based cryptography, public keys can be arbitrary bit strings, including readable representations of one’s identity.Fundação para a Ci~Encia e Tecnologia - SFRH/BPD/20528/2004

Applications of Frobenius Expansions in Elliptic Curve Cryptography

Recent developments in elliptic curve cryptography have heightened the need for fast scalar point multiplication, specially when working on environments with limited computational power. It is well known that point multiplication on elliptic curves over F_{q^m} (with m > 1) can be accelerated using Frobenius expansions. In practice, the computation is much faster than the standard double-and-add scalar multiplication. An efficient implementation of elliptic curve cryptosystems can use a Koblitz curve and convert integers into Frobenius expansions to perform fast scalar multiplications. However, this conversion of integers to Frobenius expansions would lead to extra code on the device (i.e., silicon area) and extra computational cost. According to N. Koblitz, H. Lenstra suggested that rather than choosing a random integer n and then converting to a Frobenius expansion n(\tau), in certain cryptosystems it might be more efficient to generate a random Frobenius expansion directly. The temptation then is to choose a relatively short and/or sparse value for n(\tau). If this is done then we must re-evaluate the difficulty of the discrete logarithm problem (and other computational problems). A further issue is that the existing security proofs may not directly apply. For some systems it may be necessary to develop bespoke security proofs for the Frobenius expansion case. In this thesis, we analyse the Frobenius expansion DLP and present algorithms to solve it. Furthermore, we propose a variant of a well known identification scheme designed for public key cryptography on very restricted devices. More precisely, we construct the Girault-Poupard-Stern (GPS) identification scheme for Koblitz elliptic curves using Frobenius expansions. The idea is to use Frobenius expansions throughout the protocol, so there is no need to convert between integers and Frobenius expansions. We also give a security analysis of the proposed scheme