1,720,973 research outputs found
SoK: Dlog-based Distributed Key Generation
Get PDFDistributed Key Generation (DKG) protocols are fundamental components of threshold cryptography, enabling key generation in a trustless manner for a range of cryptographic operations such as threshold encryption and signing. Of particular widespread use are DKG protocols for discrete-logarithm based cryptosystems. In this Systematization of Knowledge (SoK), we present a comprehensive analysis of existing DKG protocols in the discrete-logarithm setting, with the goal of identifying cryptographic techniques and design principles that facilitate the development of secure and resilient protocols. To offer a structured overview of the literature, we adopt a modular approach and classify DKG protocols based on their underlying network assumption and cryptographic tools. These two factors determine how DKG protocols manage secret sharing and reach consensus as their essential building blocks. We also highlight various insights and suggest future research directions that could drive further advancements in this area
Tightly Secure Threshold Signatures over Pairing-Free Groups
Get PDFThreshold signatures have been drawing lots of attention in recent years. Of particular interest are threshold signatures that are proven secure under adaptive corruptions (NIST Call 2023). Sadly, existing constructions with provable adaptive security suffer from at least one of the following drawbacks: (i) strong idealizations such as the algebraic group model (AGM), (ii) an unnatural restriction on the corruption threshold being where is the signing threshold, or (iii) prohibitively large security loss under established assumptions. Notably, point (iii) has received little to no attention in the literature on this subject.
In this work, we introduce Twinkle-T, a new threshold signature scheme which overcomes these limitations. Twinkle-T is the first scheme to have a fully tight security proof under up to adaptive corruptions without relying on the AGM. It also has a signing protocol consisting of only three rounds and thus matches the currently best threshold signature with full adaptive security Twinkle (Eurocrypt 2024) in the pairing-free discrete logarithm setting. We prove security from a standard non-interactive assumption, namely, the Decisional Diffie-Hellman (DDH) assumption
Adaptively Secure (Aggregatable) PVSS and Application to Distributed Randomness Beacons
Get PDFPublicly Verifiable Secret Sharing (PVSS) is a fundamental primitive that allows to share a secret among parties via a publicly verifiable transcript . Existing (efficient) PVSS are only proven secure against static adversaries who must choose who to corrupt ahead of a protocol execution. As a result, any protocol (e.g., a distributed randomness beacon) that builds on top of such a PVSS scheme inherits this limitation. To overcome this barrier, we revisit the security of PVSS under adaptive corruptions and show that, surprisingly, many protocols from the literature already achieve it in a meaningful way:
- We propose a new security definition for aggregatable PVSS, i.e., schemes that allow to homomorphically combine multiple transcripts into one compact aggregate transcript that shares the sum of their individual secrets. Our notion captures that if the secret shared by contains at least one contribution from an honestly generated transcript, it should not be predictable. We then prove that several existing schemes satisfy this notion against adaptive corruptions in the algebraic group model.
- To motivate our new notion, we show that it implies the adaptive security of two recent random beacon protocols, SPURT (S&P \u2722) and OptRand (NDSS \u2723), who build on top of aggregatable PVSS schemes satisfying our notion of unpredictability. For a security parameter , our result improves the communication complexity of the best known adaptively secure random beacon protocols to for synchronous networks with corruptions and partially synchronous networks with corruptions
Tightly Secure Non-Interactive BLS Multi-Signatures
Get PDFDue to their simplicity, compactness, and algebraic structure, BLS signatures are among the most widely used signatures in practice. For example, used as multi-signatures, they are integral in Ethereum\u27s proof-of-stake consensus. From the perspective of concrete security, however, BLS (multi-)signatures suffer from a security loss linear in the number of signing queries. It is well-known that this loss can not be avoided using current proof techniques.
In this paper, we introduce a new variant of BLS multi-signatures that achieves tight security while remaining fully compatible with regular BLS. In particular, our signatures can be seamlessly combined with regular BLS signatures, resulting in regular BLS signatures. Moreover, it can easily be implemented using existing BLS implementations in a black-box way. Our scheme is also one of the most efficient non-interactive multi-signatures, and in particular more efficient than previous tightly secure schemes. We demonstrate the practical applicability of our scheme by showing how proof-of-stake protocols that currently use BLS can adopt our variant for fully compatible opt-in tight security
T-Spoon: Tightly Secure Two-Round Multi-Signatures with Key Aggregation
Get PDFMulti-signatures over pairing-free cyclic groups have seen significant advancements in recent years, including achieving two-round protocols and supporting key aggregation.
Key aggregation enables the combination of multiple public keys into a single succinct aggregate key for verification and has essentially evolved from an optional feature to a requirement.
To enhance the concrete security of two-round schemes, Pan and Wagner (Eurocrypt 2023, 2024) introduced the first tightly secure constructions in this setting.
However, their schemes do not support key aggregation, and their approach inherently precludes a single short aggregate public key.
This leaves the open problem of achieving tight security and key aggregation simultaneously.
In this work, we solve this open problem by presenting the first tightly secure two-round multi-signature scheme in pairing-free groups supporting key aggregation.
As for Pan and Wagner\u27s schemes, our construction is based on the DDH assumption.
In contrast to theirs, it also has truly compact signatures, with signature size asymptotically independent of the number of signers
Tightly Secure Threshold Signatures over Pairing-Free Groups
Get PDF Threshold signatures have been drawing lots of attention in recent years. Of particular interest are threshold signatures that are proven secure under adaptive corruptions (NIST Call 2023). Sadly, existing constructions with provable adaptive security suffer from at least one of the following drawbacks: (i) strong idealizations such as the algebraic group model (AGM), (ii) an unnatural restriction on the corruption threshold being t/2 where t is the signing threshold, or (iii) prohibitively large security loss under established assumptions. Notably, point (iii) has received little to no attention in the literature on this subject. In this work, we introduce Twinkle-T, a new threshold signature scheme which overcomes these limitations. Twinkle-T is the first scheme to have a fully tight security proof under up to t adaptive corruptions without relying on the AGM. It also has a signing protocol consisting of only three rounds and thus matches the currently best threshold signature with full adaptive security Twinkle (Eurocrypt 2024) in the pairing-free discrete logarithm setting. We prove security from a standard non-interactive assumption, namely, the Decisional Diffie-Hellman (DDH) assumption, in the random oracle model. </p
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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