1,720,992 research outputs found
Block Ciphers in Idealized Models: Automated Proofs and New Security Results
Get PDFWe develop and implement AlgoROM, a tool to systematically analyze the security of a wide class of symmetric primitives in idealized models of computation. The schemes that we consider are those that can be expressed over an alphabet consisting of XOR and function symbols for hash functions, permutations, or block ciphers. We implement our framework in OCaml and apply it to a number of prominent constructions, which include the Luby-Rackoff (LR), key-alternating Feistel (KAF), and iterated Even-Mansour (EM) ciphers, as well as substitution-permutation networks (SPN). The security models we consider are (S)PRP, and strengthenings thereof under related-key (RK), key-dependent message (KD), and more generally key-correlated (KC) attacks. Using AlgoROM, we are able to reconfirm a number of classical and previously established security theorems, and in one case we identify a gap in a proof from the literature (Connolly et al., ToSC'19). However, most results that we prove with AlgoROM are new. In particular, we obtain new positive results for LR, KAF, EM, and SPN in the above models. Our results better reflect the configurations actually implemented in practice, as they use a single idealized primitive. In contrast to many existing tools, our automated proofs do not operate in symbolic models, but rather in the standard probabilistic model for cryptography
Extensions of Public-Key, Identity-Based and Certificateless Encryption Schemes
No full textIn this work, we first study extensions and applications of the identity-based encryption (IBE) primitive, focusing on generic constructions. We first define what is meant by an identity-based key encapsulation mechanism before extending it to the multi-recipient setting. We then propose an efficient multi-recipient scheme based on bilinear maps and then move on to investigate the properties of publickey schemes which allow for generic and efficient construction of multi-recipient encryption schemes via randomness-reuse. We conclude this part by proposing a generic construction of workflow cryptosystems, where encryption is performed with respect to an access structure, based on any IBE scheme. We then turn our attention to the certificateless encryption primitive and extend it to the hybrid encryption paradigm. Subsequently, a certificateless key encapsulation mechanism based on weakly secure identity-based and public-key encryption schemes is constructed. Next, by introducing the first provably secure certificateless signcryption scheme, we demonstrate how one can achieve two of the most important security goals in cryptography, namely confidentiality and authenticity (including non-repudiation) of data, efficiently in the certificateless scenario.In this work, we first study extensions and applications of the identity-based encryption (IBE) primitive, focusing on generic constructions. We first define what is meant by an identity-based key encapsulation mechanism before extending it to the multi-recipient setting. We then propose an efficient multi-recipient scheme based on bilinear maps and then move on to investigate the properties of publickey schemes which allow for generic and efficient construction of multi-recipient encryption schemes via randomness-reuse. We conclude this part by proposing a generic construction of workflow cryptosystems, where encryption is performed with respect to an access structure, based on any IBE scheme. We then turn our attention to the certificateless encryption primitive and extend it to the hybrid encryption paradigm. Subsequently, a certificateless key encapsulation mechanism based on weakly secure identity-based and public-key encryption schemes is constructed. Next, by introducing the first provably secure certificateless signcryption scheme, we demonstrate how one can achieve two of the most important security goals in cryptography, namely confidentiality and authenticity (including non-repudiation) of data, efficiently in the certificateless scenario
Innovative security solutions for information technology and communications: 10th international conference, SECITC 2017, Bucharest, Romania, June 8-9, 2017, revised selected papers
No full textInnovative Security Solutions for Information Technology and Communications: 10th International Conference, SecITC 2017, Bucharest, Romania, June 8–9, 2017, Revised Selected Papers
No full textInternational audienc
Coding and Cryptography 2007
No full textWe extend the generic framework of reproducibility for reuse
of randomness in multi-recipient encryption schemes as proposed by Bel-
lare et al. (PKC 2003). A new notion of weak reproducibility captures not
only encryption schemes which are (fully) reproducible under the criteria
given in the previous work, but also a class of efficient schemes which can
only be used in the single message setting. In particular, we are able to
capture the single message schemes suggested by Kurosawa (PKC 2002),
which are more efficient than the direct adaptation of the multiple mes-
sage schemes studied by Bellare et al. Our study of randomness reuse in
key encapsulation mechanisms provides an additional argument for the
relevance of these results: by taking advantage of our weak reproducibil-
ity notion, we are able to generalise and improve multi-recipient KEM
constructions found in literature. We also propose an efficient multi-
recipient KEM provably secure in the standard model and conclude the
paper by proposing a notion of direct reproducibility which enables tighter
security reductions
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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