349 research outputs found
Faster software for fast endomorphisms
GLV curves (Gallant et al.) have performance advantages over standard elliptic curves, using half the number of point doublings for scalar multiplication. Despite their introduction in 2001, implementations of the GLV method have yet to permeate widespread software libraries. Furthermore, side-channel vulnerabilities, specifically cache-timing attacks, remain unpatched in the OpenSSL code base since the first attack in 2009 (Brumley and Hakala) even still after the most recent attack in 2014 (Benger et al.). This work reports on the integration of the GLV method in OpenSSL for curves from 160 to 256 bits, as well as deploying and evaluating two side-channel defenses. Performance gains are up to 51%, and with these improvements GLV curves are now the fastest elliptic curves in OpenSSL for these bit sizes
The Q-curve construction for endomorphism-accelerated elliptic curves
We give a detailed account of the use of -curve reductions to
construct elliptic curves over with efficiently computable
endomorphisms, which can be used to accelerate elliptic curve-based
cryptosystems in the same way as Gallant--Lambert--Vanstone (GLV) and
Galbraith--Lin--Scott (GLS) endomorphisms. Like GLS (which is a degenerate case
of our construction), we offer the advantage over GLV of selecting from a much
wider range of curves, and thus finding secure group orders when is fixed
for efficient implementation. Unlike GLS, we also offer the possibility of
constructing twist-secure curves. We construct several one-parameter families
of elliptic curves over equipped with efficient
endomorphisms for every p \textgreater{} 3, and exhibit examples of
twist-secure curves over for the efficient Mersenne prime
.Comment: To appear in the Journal of Cryptology. arXiv admin note: text
overlap with arXiv:1305.540
Computing cardinalities of Q-curve reductions over finite fields
We present a specialized point-counting algorithm for a class of elliptic
curves over F\_{p^2} that includes reductions of quadratic Q-curves modulo
inert primes and, more generally, any elliptic curve over F\_{p^2} with a
low-degree isogeny to its Galois conjugate curve. These curves have interesting
cryptographic applications. Our algorithm is a variant of the
Schoof--Elkies--Atkin (SEA) algorithm, but with a new, lower-degree
endomorphism in place of Frobenius. While it has the same asymptotic asymptotic
complexity as SEA, our algorithm is much faster in practice.Comment: To appear in the proceedings of ANTS-XII. Added acknowledgement of
Drew Sutherlan
Distribution of periodic trajectories of Anosov C-system
The hyperbolic Anosov C-systems have a countable set of everywhere dense
periodic trajectories which have been recently used to generate pseudorandom
numbers. The asymptotic distribution of periodic trajectories of C-systems with
periods less than a given number is well known, but a deviation of this
distribution from its asymptotic behaviour is less known. Using fast
algorithms, we are studying the exact distribution of periodic trajectories and
their deviation from asymptotic behaviour for hyperbolic C-systems which are
defined on high dimensional tori and are used for Monte-Carlo simulations. A
particular C-system which we consider in this article is the one which was
implemented in the MIXMAX generator of pseudorandom numbers. The generator has
the best combination of speed, reasonable size of the state, and availability
for implementing the parallelization and is currently available generator in
the ROOT and CLHEP software packages at CERN.Comment: 22 pages, 14 figure
Fast, uniform, and compact scalar multiplication for elliptic curves and genus 2 Jacobians with applications to signature schemes
We give a general framework for uniform, constant-time one-and
two-dimensional scalar multiplication algorithms for elliptic curves and
Jacobians of genus 2 curves that operate by projecting to the x-line or Kummer
surface, where we can exploit faster and more uniform pseudomultiplication,
before recovering the proper "signed" output back on the curve or Jacobian.
This extends the work of L{\'o}pez and Dahab, Okeya and Sakurai, and Brier and
Joye to genus 2, and also to two-dimensional scalar multiplication. Our results
show that many existing fast pseudomultiplication implementations (hitherto
limited to applications in Diffie--Hellman key exchange) can be wrapped with
simple and efficient pre-and post-computations to yield competitive full scalar
multiplication algorithms, ready for use in more general discrete
logarithm-based cryptosystems, including signature schemes. This is especially
interesting for genus 2, where Kummer surfaces can outperform comparable
elliptic curve systems. As an example, we construct an instance of the Schnorr
signature scheme driven by Kummer surface arithmetic
PyTomography: A Python Library for Quantitative Medical Image Reconstruction
Background: There is a scarcity of open-source libraries in medical imaging
dedicated to both (i) the development and deployment of novel reconstruction
algorithms and (ii) support for clinical data.
Purpose: To create and evaluate a GPU-accelerated, open-source, and
user-friendly image reconstruction library, designed to serve as a central
platform for the development, validation, and deployment of novel tomographic
reconstruction algorithms.
Methods: PyTomography was developed using Python and inherits the
GPU-accelerated functionality of PyTorch for fast computations. The software
uses a modular design that decouples the system matrix from reconstruction
algorithms, simplifying the process of integrating new imaging modalities or
developing novel reconstruction techniques. As example developments, SPECT
reconstruction in PyTomography is validated against both vendor-specific
software and alternative open-source libraries. Bayesian reconstruction
algorithms are implemented and validated.
Results: PyTomography is consistent with both vendor-software and alternative
open source libraries for standard SPECT clinical reconstruction, while
providing significant computational advantages. As example applications,
Bayesian reconstruction algorithms incorporating anatomical information are
shown to outperform the traditional ordered subset expectation maximum (OSEM)
algorithm in quantitative image analysis. PSF modeling in PET imaging is shown
to reduce blurring artifacts.
Conclusions: We have developed and publicly shared PyTomography, a highly
optimized and user-friendly software for quantitative image reconstruction of
medical images, with a class hierarchy that fosters the development of novel
imaging applications.Comment: 26 pages, 7 figure
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