291 research outputs found
Secure Grouping Protocol Using a Deck of Cards
We consider a problem, which we call secure grouping, of dividing a number of
parties into some subsets (groups) in the following manner: Each party has to
know the other members of his/her group, while he/she may not know anything
about how the remaining parties are divided (except for certain public
predetermined constraints, such as the number of parties in each group). In
this paper, we construct an information-theoretically secure protocol using a
deck of physical cards to solve the problem, which is jointly executable by the
parties themselves without a trusted third party. Despite the non-triviality
and the potential usefulness of the secure grouping, our proposed protocol is
fairly simple to describe and execute. Our protocol is based on algebraic
properties of conjugate permutations. A key ingredient of our protocol is our
new techniques to apply multiplication and inverse operations to hidden
permutations (i.e., those encoded by using face-down cards), which would be of
independent interest and would have various potential applications
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
Mixed Integer Programming Models for Finite Automaton and Its Application to Additive Differential Patterns of Exclusive-Or
Inspired by Fu et al. work on modeling the exclusive-or differential property of the modulo addition as an mixed-integer programming problem, we propose a method with which any finite automaton can be formulated as an mixed-integer programming model. Using this method, we show how to construct a mixed integer programming model whose feasible region is the set of all differential patterns \u27s, such that . We expect that this may be useful in automatic differential analysis with additive difference
Improvement of algebraic attacks for solving superdetermined MinRank instances
The MinRank (MR) problem is a computational problem that arises in many
cryptographic applications. In Verbel et al. (PQCrypto 2019), the authors
introduced a new way to solve superdetermined instances of the MinRank problem,
starting from the bilinear Kipnis-Shamir (KS) modeling. They use linear algebra
on specific Macaulay matrices, considering only multiples of the initial
equations by one block of variables, the so called ''kernel'' variables. Later,
Bardet et al. (Asiacrypt 2020) introduced a new Support Minors modeling (SM),
that consider the Pl{\"u}cker coordinates associated to the kernel variables,
i.e. the maximal minors of the Kernel matrix in the KS modeling. In this paper,
we give a complete algebraic explanation of the link between the (KS) and (SM)
modelings (for any instance). We then show that superdetermined MinRank
instances can be seen as easy instances of the SM modeling. In particular, we
show that performing computation at the smallest possible degree (the ''first
degree fall'') and the smallest possible number of variables is not always the
best strategy. We give complexity estimates of the attack for generic random
instances.We apply those results to the DAGS cryptosystem, that was submitted
to the first round of the NIST standardization process. We show that the
algebraic attack from Barelli and Couvreur (Asiacrypt 2018), improved in Bardet
et al. (CBC 2019), is a particular superdetermined MinRank instance.Here, the
instances are not generic, but we show that it is possible to analyse the
particular instances from DAGS and provide a way toselect the optimal
parameters (number of shortened positions) to solve a particular instance
Critical systems librarianship
In this chapter we perform a meta-analysis and synthesize existing critical library and information studies work into a cohesive approach to critical systems librarianship, informed by diverse perspectives and ethical lenses. We seek to enable and facilitate a critically-informed, reflective, and reflexive approach to systems work with specific focus on how information technologies are applied in library work. Critical systems librarianship centrally involves critical reflection which allows systems workers to question the underlying values, assumptions, and power relations ingrained in their daily practices and the institutions within which they work: this is essential to both theoretical questioning and developing strategies to contest power imbalances
A Note on Adversarial Online Complexity in Security Proofs of Duplex-Based Authenticated Encryption Modes
This note examines a nuance in the methods employed for counting the adversarial online complexity in the security proofs of duplex-based modes, with a focus on authenticated encryption. A recent study by Gilbert et al., reveals an attack on a broad class of duplex-based authenticated encryption modes. In particular, their approach to quantifying the adversarial online complexity, which capture realistic attack scenarios, includes certain queries in the count which are not in the security proofs. This note analyzes these differences and concludes that the attack of Gilbert et al, for certain parameter choices, matches the security bound
Critical systems librarianship
In this chapter we perform a meta-analysis and synthesize existing critical library and information studies work into a cohesive approach to critical systems librarianship, informed by diverse perspectives and ethical lenses. We seek to enable and facilitate a critically-informed, reflective, and reflexive approach to systems work with specific focus on how information technologies are applied in library work. Critical systems librarianship centrally involves critical reflection which allows systems workers to question the underlying values, assumptions, and power relations ingrained in their daily practices and the institutions within which they work: this is essential to both theoretical questioning and developing strategies to contest power imbalances
PROPYLA: Privacy Preserving Long-Term Secure Storage
An increasing amount of sensitive information today is stored electronically
and a substantial part of this information (e.g., health records, tax data,
legal documents) must be retained over long time periods (e.g., several decades
or even centuries). When sensitive data is stored, then integrity and
confidentiality must be protected to ensure reliability and privacy. Commonly
used cryptographic schemes, however, are not designed for protecting data over
such long time periods. Recently, the first storage architecture combining
long-term integrity with long-term confidentiality protection was proposed
(AsiaCCS'17). However, the architecture only deals with a simplified storage
scenario where parts of the stored data cannot be accessed and verified
individually. If this is allowed, however, not only the data content itself,
but also the access pattern to the data (i.e., the information which data items
are accessed at which times) may be sensitive information. Here we present the
first long-term secure storage architecture that provides long-term access
pattern hiding security in addition to long-term integrity and long-term
confidentiality protection. To achieve this, we combine information-theoretic
secret sharing, renewable timestamps, and renewable commitments with an
information-theoretic oblivious random access machine. Our performance analysis
of the proposed architecture shows that achieving long-term integrity,
confidentiality, and access pattern hiding security is feasible.Comment: Few changes have been made compared to proceedings versio
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