1,720,963 research outputs found
On the Design and Security of Post-Quantum Aggregate Signatures
Get PDFL'abstract è presente nell'allegato / the abstract is in the attachmen
History-Free Sequential Aggregation of Hash-and-Sign Signatures
Get PDFA sequential aggregate signature (SAS) scheme allows multiple users to sequentially combine their respective signatures in order to reduce communication costs. Historically, early proposals required the use of trapdoor permutation (e.g., RSA). In recent years, a number of attempts have been made to extend SAS schemes to post-quantum assumptions. Many post-quantum signatures have been proposed in the hash-and-sign paradigm, which requires the use of trapdoor functions and appears to be an ideal candidate for sequential aggregation attempts. However, the hardness in achieving post-quantum one-way permutations makes it difficult to obtain similarly general constructions. Direct attempts at generalizing permutation-based schemes have been proposed, but they either lack formal security or require additional properties on the trapdoor function, which are typically not available for multivariate or code-based functions. In this paper, we propose a (partial-signature) history-free SAS within the probabilistic hash-and-sign with retry paradigm, generalizing existing techniques to generic trapdoor functions. We prove the security of our scheme in the random oracle model and we instantiate our construction with three post-quantum schemes, comparing their compression capabilities. Finally, we discuss how direct extensions of permutation-based SAS schemes are not possible without additional properties, showing the lack of security of two existing multivariate schemes
Group factorisation for smaller signatures from cryptographic group actions
Get PDFCryptographic group actions have gained significant attention in recent years for their application on post-quantum Sigma protocols and digital signatures. In NIST’s recent additional
call for post-quantum signatures, three relevant proposals are based on group actions: LESS,
MEDS, and ALTEQ. This work explores signature optimisations leveraging a group’s factorisation. We show that if the group admits a factorisation as a semidirect product of subgroups,
the group action can be restricted on a quotient space under the equivalence relation induced
by the factorisation. If the relation is efficiently decidable, we show that it is possible to
construct an equivalent Sigma protocol for a relationship that depends only on one of the
subgroups. Moreover, if a special class of representative of the quotient space is efficiently
computable via a canonical form, the restricted action is effective and does not incur in
security loss. Finally, we apply these techniques to the group actions underlying LESS and
MEDS, showing how they will affect the length of signatures and public keys
Security of fixed-weight repetitions of special-sound multi-round interactive proofs
No full textInteractive proofs are a cornerstone of modern cryptography and, as such, used in many areas, from digital signatures to multi-party computation. Often the knowledge error
of an interactive proof is not small enough and thus needs to be reduced. This is usually achieved by repeating the interactive proof in parallel t times. Recently, it was shown that the t-fold parallel repetition of any -special-sound multi-round public-coin interactive proof reduces the knowledge error from to , which is optimal. However, parallel repetitions lead to an increase in transcript size. A common technique to mitigate this drawback, which is often employed in digital signatures obtained by using the Fiat–Shamir transform, is to use fixed-weight challenges, i.e. vectors of challenges having a constant number of entries (for which the last component is) equal to a fixed value. While widely used, this method has not been fully assessed from a security standpoint. In particular, the effect of the technique on the knowledge error of repeated interactive proofs has remained unstudied. In this work, we fill the gap and prove that a fixed-weight repetition of a -special-sound multi-round public-coin interactive proof is still knowledge sound. We provide an explicit bound for the knowledge error of the protocol, proving that it matches the maximum cheating probability of a dishonest prover. Our results apply to some recently-proposed digital signatures which are supposed to be quantum resistant, for example the code-based signature CROSS
A Framework for Group Action-Based Multi-signatures and Applications to LESS, MEDS, and ALTEQ
Get PDFA multi-signature scheme allows a list of signers to sign a
common message. They are widely used in scenarios where the same
message must be signed and transmitted by .N users, and, instead of
concatenating .N individual signatures, employing a multi-signature can
reduce the data to be sent. In recent years there have been numerous
practical proposals in the discrete logarithm setting, such as MuSig2
(CRYPTO’21) for the Schnorr signature. Recently, these attempts have
been extended to post-quantum assumptions, with lattice-based proposals such as MuSig-L (CRYPTO’22). Given the growth of group actionbased signatures, a natural question is whether a multi-signature can be
built on the same models. In this work, we present the first construction
of such a primitive relying on group action assumptions. We obtain a 3-
round scheme achieving concurrent security in the ROM. Moreover, we
instantiate it using the three candidates to the additional post-quantum
NIST’s call, namely LESS, MEDS and ALTEQ, obtaining a good compression rate for different parameters set
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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