1,332 research outputs found
A kilobit hidden SNFS discrete logarithm computation
We perform a special number field sieve discrete logarithm computation in a
1024-bit prime field. To our knowledge, this is the first kilobit-sized
discrete logarithm computation ever reported for prime fields. This computation
took a little over two months of calendar time on an academic cluster using the
open-source CADO-NFS software. Our chosen prime looks random, and
has a 160-bit prime factor, in line with recommended parameters for the Digital
Signature Algorithm. However, our p has been trapdoored in such a way that the
special number field sieve can be used to compute discrete logarithms in
, yet detecting that p has this trapdoor seems out of reach.
Twenty-five years ago, there was considerable controversy around the
possibility of back-doored parameters for DSA. Our computations show that
trapdoored primes are entirely feasible with current computing technology. We
also describe special number field sieve discrete log computations carried out
for multiple weak primes found in use in the wild. As can be expected from a
trapdoor mechanism which we say is hard to detect, our research did not reveal
any trapdoored prime in wide use. The only way for a user to defend against a
hypothetical trapdoor of this kind is to require verifiably random primes
Root optimization of polynomials in the number field sieve
The general number field sieve (GNFS) is the most efficient algorithm known
for factoring large integers. It consists of several stages, the first one
being polynomial selection. The quality of the chosen polynomials in polynomial
selection can be modelled in terms of size and root properties. In this paper,
we describe some algorithms for selecting polynomials with very good root
properties.Comment: 16 pages, 18 reference
Discrete logarithm computations over finite fields using Reed-Solomon codes
Cheng and Wan have related the decoding of Reed-Solomon codes to the
computation of discrete logarithms over finite fields, with the aim of proving
the hardness of their decoding. In this work, we experiment with solving the
discrete logarithm over GF(q^h) using Reed-Solomon decoding. For fixed h and q
going to infinity, we introduce an algorithm (RSDL) needing O (h! q^2)
operations over GF(q), operating on a q x q matrix with (h+2) q non-zero
coefficients. We give faster variants including an incremental version and
another one that uses auxiliary finite fields that need not be subfields of
GF(q^h); this variant is very practical for moderate values of q and h. We
include some numerical results of our first implementations
Solving discrete logarithms on a 170-bit MNT curve by pairing reduction
Pairing based cryptography is in a dangerous position following the
breakthroughs on discrete logarithms computations in finite fields of small
characteristic. Remaining instances are built over finite fields of large
characteristic and their security relies on the fact that the embedding field
of the underlying curve is relatively large. How large is debatable. The aim of
our work is to sustain the claim that the combination of degree 3 embedding and
too small finite fields obviously does not provide enough security. As a
computational example, we solve the DLP on a 170-bit MNT curve, by exploiting
the pairing embedding to a 508-bit, degree-3 extension of the base field.Comment: to appear in the Lecture Notes in Computer Science (LNCS
The fluctuations in the number of points of smooth plane curves over finite fields
In this note, we study the fluctuations in the number of points of smooth
projective plane curves over finite fields as is fixed and
the genus varies. More precisely, we show that these fluctuations are predicted
by a natural probabilistic model, in which the points of the projective plane
impose independent conditions on the curve. The main tool we use is a geometric
sieving process introduced by Poonen.Comment: 12 page
Discrete logarithms in curves over finite fields
A survey on algorithms for computing discrete logarithms in Jacobians of
curves over finite fields
Bayesian adaptation
In the need for low assumption inferential methods in infinite-dimensional
settings, Bayesian adaptive estimation via a prior distribution that does not
depend on the regularity of the function to be estimated nor on the sample size
is valuable. We elucidate relationships among the main approaches followed to
design priors for minimax-optimal rate-adaptive estimation meanwhile shedding
light on the underlying ideas.Comment: 20 pages, Propositions 3 and 5 adde
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