1,720,958 research outputs found
Multi-Message Quantum Broadcast with Fine-Grained Access Control
Get PDFSeveral subscription-based systems require fine-grained,
dynamic access control, which traditional broadcast
encryption schemes fail to handle efficiently. Attribute-based
and policy-based access structures offer a flexible and scalable
solution by encoding access rules directly into the encryption
mechanism. With the advent and development of quantum
networks, attribute-based and policy-based quantum broadcast
encryption (PBQBE) becomes necessary for enforcing such
controls securely in a post-quantum world. In this paper, we
present a general construction of quantum broadcast encryption
for multiple messages simultaneously, based on routing and
traversing a given attribute-based and, consequently, a policy-based
access tree when a user satisfies a unique policy. Our
scheme can handle dynamic systems with frequently changing
access patterns and can be deployed seamlessly with classical
systems. Compared to existing constructions, our scheme offers
hierarchical access, policy control, scalability, and revocation
while maintaining provable security guarantees
Computational Quantum Anamorphic Encryption and Anamorphic Secret Sharing
Get PDFThe concept of anamorphic encryption, first formally introduced by Persiano et al. in their influential 2022 paper titled ``Anamorphic Encryption: Private Communication Against a Dictator,\u27\u27 enables embedding covert messages within ciphertexts. One of the key distinctions between a ciphertext embedding a covert message and an original ciphertext, compared to an anamorphic ciphertext, lies in the indistinguishability between the original ciphertext and the anamorphic ciphertext. This encryption procedure has been defined based on a public-key cryptosystem. Initially, we present a quantum analogue of the classical anamorphic encryption definition that is based on public-key encryption. Additionally, we introduce a definition of quantum anamorphic encryption that relies on symmetric key encryption. Furthermore, we provide a detailed generalized construction of quantum anamorphic symmetric key encryption within a general framework, which involves taking any two quantum density matrices of any different dimensions and constructing a single quantum density matrix, which is the quantum anamorphic ciphertext containing ciphertexts of both of them. Subsequently, we introduce a definition of computational anamorphic secret-sharing and extend the work of \c{C}akan et al. on computational quantum secret-sharing to computational quantum anamorphic secret-sharing, specifically addressing scenarios with multiple messages, multiple keys, and a single share function. This proposed secret-sharing scheme demonstrates impeccable security measures against quantum adversaries
Attribute-based Quantum Broadcast Encryption with Composite Policies via Symmetric Unitary t-Designs
Get PDFIn an emerging era of quantum technologies, securing quantum communications is paramount. In this paper, we introduce two frameworks for attribute-based quantum broadcast encryption (AB-QBE), enabling fine-grained access control over sensitive quantum data. The first scheme, Multi-Policy Quantum Private Broadcast Encryption (MP-QPBE), leverages symmetric unitary -designs to construct a protocol where decryption is possible upon satisfying a composite set of access policies simultaneously. This approach ensures that a user can only access the broadcasted quantum state if their attributes fulfill multiple predefined criteria. In our MP-QPBE, we first perform symmetrization of the initial quantum message for the encryption of the tensor product of distinct pure states, a scenario not directly addressed by previous quantum private broadcasting schemes. We demonstrate that this method is information-theoretically secure. The second scheme, Component-wise Independent Quantum Broadcast Encryption (CI-QBE), offers an alternative, lossless approach where each quantum message is encrypted independently using a unitary -design. It provides greater flexibility and is applicable to arbitrary quantum states, including mixed states, without the information loss inherent in symmetrization. We provide a comprehensive security analysis for both constructions, proving their robustness against unauthorized users and adversaries with quantum side information. A comparative analysis highlights the trade-offs between the two schemes in terms of security guarantees, quantum resource requirements, and practical applicability, offering a nuanced perspective on designing secure multi-user quantum communication systems
Hypercube and Cascading-based Algorithms for Secret Sharing Schemes
Get PDFSecret sharing is a very useful way to maintain secrecy of private data when
stored in a distributed way among several nodes. Two significant questions
in this area are 1. how to accommodate new nodes and assign shares to the
new nodes, the problem becomes harder if the number of joining nodes or the
access structure is not known in advance and can be (potentially) unbounded
and 2. to reduce the computational complexity of secret sharing schemes. In
this paper we propose two new constructions of such secret sharing schemes
based on different combinatorial structures. The first construction is based
on generalized paths joining the opposite vertices of a hypercube which has
been divided into smaller hypercubes. The second construction is a forest-
based construction utilizing a dynamic data structure technique known as
fractional cascading. The generalized path we call a pavement is new to this
paper. Both our constructions use a new secret redistribution scheme to
assign and re-assign shares to nodes. Towards the second question we show
that allowing certain trade-offs, the constructions are implementable by
circuits which is the lowest complexity class in which secret sharing and
reconstruction is possible. To the best of the knowledge of the authors, none
of the similar existing schemes (evolving or dynamic) are computable
and this paper for the first time combines the idea of hypercubes and dynamic
data structures with secret sharing for preserving long-term confidentiality of secret data
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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