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Efficient proactive secret sharing

Jacqueline Brendel, Denise Demirel
2016 2016 14th Annual Conference on Privacy, Security and Trust (PST)  
The secure storage of long-lived sensitive data is constantly growing in its relevance due to the ever increasing digitization of documents. One very important challenge of this research field is to provide confidentiality for the stored data even in the long term. The only known approach to achieve this, as required, for instance, for medical records, is to use proactive secret sharing. However, all currently known schemes suffer from being inefficient. They require information-theoretic
more » ... communication channels between any two shareholders and between the client and each shareholder and come with a high communication complexity. Thus, this work addresses the scenario where only a subset of servers holding shares is connected via private channels. Furthermore, it is sufficient if there is only one private channel between the client and one shareholder. In addition to improving practicability the presented proactive secret sharing solution, called EPSS, performs data aggregation to provide an efficient solution with respect to the communication complexity. Nevertheless, it still provides unconditional confidentiality for the data at rest and towards external attackers eavesdropping the communication channels.
doi:10.1109/pst.2016.7907013 dblp:conf/pst/BrendelD16 fatcat:cxdperscaveltkb5f6t7jaxlym

The Provable Security of Ed25519: Theory and Practice [article]

Jacqueline Brendel, Cas Cremers, Dennis Jackson, Mang Zhao
2020 IACR Cryptology ePrint Archive  
A standard requirement for a signature scheme is that it is existentially unforgeable under chosen message attacks (EUF-CMA), alongside other properties of interest such as strong unforgeability (SUF-CMA), and resilience against key substitution attacks. Remarkably, no detailed proofs have ever been given for these security properties for EdDSA, and in particular its Ed25519 instantiations. Ed25519 is one of the most efficient and widely used signature schemes, and different instantiations of
more » ... 25519 are used in protocols such as TLS 1.3, SSH, Tor, ZCash, and WhatsApp/Signal. The differences between these instantiations are subtle, and only supported by informal arguments, with many works assuming results can be directly transferred from Schnorr signatures. Similarly, several proofs of protocol security simply assume that Ed25519 satisfies properties such as EUF-CMA or SUF-CMA. In this work we provide the first detailed analysis and security proofs of Ed25519 signature schemes. While the design of the schemes follows the well-established Fiat-Shamir paradigm, which should guarantee existential unforgeability, there are many side cases and encoding details that complicate the proofs, and all other security properties needed to be proven independently. Our work provides scientific rationale for choosing among several Ed25519 variants and understanding their properties, fills a much needed proof gap in modern protocol proofs that use these signatures, and supports further standardisation efforts.
dblp:journals/iacr/BrendelCJZ20 fatcat:vrqksl7r3vgezdubpufh2yxyvm

PRF-ODH: Relations, Instantiations, and Impossibility Results [chapter]

Jacqueline Brendel, Marc Fischlin, Felix Günther, Christian Janson
2017 Lecture Notes in Computer Science  
Lastly, Brendel and Fischlin [BF17] require to query both key shares multiple times, which our definition captures as well by choosing the parameters as l = m and r = m. Design options.  ... 
doi:10.1007/978-3-319-63697-9_22 fatcat:gjowiufwmrg7nk72swbcyy6hvu

Zero Round-Trip Time for the Extended Access Control Protocol [chapter]

Jacqueline Brendel, Marc Fischlin
2017 Lecture Notes in Computer Science  
In accordance with the systematic study of the PRF-ODH assumption by Brendel et al.  ... 
doi:10.1007/978-3-319-66402-6_18 fatcat:63tfavxjj5bi7kkilg7agrs2de

Challenges in Proving Post-Quantum Key Exchanges Based on Key Encapsulation Mechanisms [article]

Jacqueline Brendel, Marc Fischlin, Felix Günther, Christian Janson, Douglas Stebila
2019 IACR Cryptology ePrint Archive  
Brendel et al.  ... 
dblp:journals/iacr/BrendelF0JS19 fatcat:pyw5drb2wffbfd7jcaluckxpei

Breakdown Resilience of Key Exchange Protocols and the Cases of NewHope and TLS 1.3 [article]

Jacqueline Brendel, Marc Fischlin, Felix Günther
2017 IACR Cryptology ePrint Archive  
Broken cryptographic algorithms and hardness assumptions are a constant threat to realworld protocols. Prominent examples are hash functions for which collisions become known, or numbertheoretic assumptions which are threatened by advances in quantum computing. Especially when it comes to key exchange protocols, the switch to quantum-resistant primitives has begun and aims to protect today's secrets against future developments, moving from common Diffie-Hellman-based solutions to
more » ... rrors-based approaches, often via intermediate hybrid designs. To this date there exists no security notion for key exchange protocols that could capture the scenario of breakdowns of arbitrary cryptographic primitives to argue security of prior or even ongoing and future sessions. In this work we extend the common Bellare-Rogaway model to capture breakdown resilience of key exchange protocols. Our extended model allows us to study security of a protocol even in case of unexpected failure of employed primitives, may it be number-theoretic assumptions, hash functions, signature schemes, key derivation functions, etc. We then apply our security model to analyze two real-world protocols, showing that breakdown resilience for certain primitives is achieved by both an authenticated variant of the post-quantum secure key encapsulation mechanism NewHope (Alkim et al.) which is a second round candidate in the Post Quantum Cryptography standardization process by NIST, as well as by TLS 1.3, which has recently been standardized as RFC 8446 by the Internet Engineering Task Force. Finally, we analyze the security of a generic hybrid key exchange protocol, formally showing how such designs ensure resilience against breakdowns of one of their key exchange components.
dblp:journals/iacr/BrendelFG17 fatcat:ixaxyx6d45cabiadb2xt4knziu

Future-Proofing Key Exchange Protocols

Jacqueline Brendel
The following model description here is largely taken verbatim from Brendel, Fischlin, and Günther [BFG17] . Notation and overview.  ...  An alternative recent approach to model security of protocols in which a component fails is the breakdown resilience model of Brendel, Fischlin, and Günther [BFG17, BFG19] which in its stronger formulation  ... 
doi:10.25534/tuprints-00009642 fatcat:2edjtbzotbanjblfy4kv5e7rui

Post-quantum Asynchronous Deniable Key Exchange and the Signal Handshake

Jacqueline Brendel, Rune Fiedler, Felix Günther, Christian Janson, Douglas Stebila, Goichiro Hanaoka, Junji Shikata, Yohei Watanabe
Brendel, Fischlin, Günther, Janson, and Stebila [15] previously considered the question of building a postquantum version of the Signal handshake, highlighting many of these problems.  ... 
doi:10.3929/ethz-b-000520264 fatcat:nyqwmst4djbgxhwrzws74qqdn4

Identification of distinct nanoparticles and subsets of extracellular vesicles by asymmetric flow field-flow fractionation

Haiying Zhang, Daniela Freitas, Han Sang Kim, Kristina Fabijanic, Zhong Li, Haiyan Chen, Milica Tesic Mark, Henrik Molina, Alberto Benito Martin, Linda Bojmar, Justin Fang, Sham Rampersaud (+30 others)
2018 Nature Cell Biology  
doi:10.1038/s41556-018-0040-4 pmid:29459780 fatcat:ie4hsp7a7jhyvlipfvlqsyp4bq

Page 996 of The Journal of Applied Ecology Vol. 34, Issue 4 [page]

1997 The Journal of Applied Ecology  
Stork, unpub¬ lished data); 18% in Bornean lowland rain forest trees (Stork 1991); but only 1-4% in Sulawesi, Indonesia (Stork & Brendell 1990).  ...  This work would have been impossible without the support and encouragement of Roger Leakey, Paulinus Ngeh, Andy Roby and Zac Tchoundjeu, and technical help from, in particular, Marcel Mboglen, Jacqueline  ... 

Page 70 of Monatshefte Vol. 39, Issue 1 [page]

1947 Monatshefte  
.; Jacquelin A. MacNaughton, Ph.D.; Be Masche; Jean T. Wilde; Frederick Wolinsky, Ph. D.; Rudolf Kayser, Ph.D.; Ralph P. Rosenberg, Ph.D.; Olga Steiner, Ph. D. Prof.: E. Heyse Dummer,* Ph.D.  ...  Brendel; Gloria C. Winslow; Howard French. Prof.: Erich Funke,* Ph.D. Assoc. Prof.: Herbert O. Lyte, Ph. D. Asst. Profs.: Wolfgang Paulsen, Ph. D.; Fred L. Fehling, Ph.D. IJnstrs.: Gerta B.  ... 

Page 70 of Monatshefte Vol. 39, Issue 1 [page]

1947 Monatshefte  
Brendel; Gloria C. Winslow; Howard French. Prof.: Erich Funke,* Ph.D. Assoc. Prof.: Herbert O. Lyte, Ph. D. Asst. Profs.: Wolfgang Paulsen, Ph. D.; Fred L. Fehling, Ph.D. Instrs.: Gerta B.  ...  .; Jacquelin A. MacNaughton, Ph.D.; Bertha Masche; Jean T. Wilde; Frederick Wolinsky, Ph. D.; Rudolf Kayser, Ph.D.; Ralph P. Rosenberg, Ph.D.; Olga Steiner, Ph. D. Prof.: E. Heyse Dummer,* Ph.D.  ... 

Page 1354 of Psychological Abstracts Vol. 57, Issue 5 [page]

1977 Psychological Abstracts  
., 11022 Brehmer, Berndt, 9513 Brendel, Harold J., 10787 Brengelmann, J. C., 10655 Bresnahan, Jacqueline C., 9799 Brewer, Bran R., 11103 Brewer, Marilynn B., 9328 Brickman, Sidney, 11223 Brief.  ... 

From the Editors' Desk: Peer Review Now and in the Future

Richard L. Kravitz, Mitchell D. Feldman
2011 Journal of general internal medicine  
Gregory Feldman, Roger Felix, Kaytura Feng, Qiushi Feng, Yongqing Fernander, Anita Fickel, Jacqueline* Filardo, Giovanni Filice, Gregory Fingerhood, Michael Finkelstein, Joseph Fish, Laura  ...  Ebony Boutin-Foster, Carla Bovet, Pascal Boyd, Cynthia Branch, William Brauner, Daniel Brendel, Rebecca Brenner, Darren Brett, Belle Briesacher, Becky Brittain, Kelly Brody, Howard* Brophy, Jay Brotman  ... 
doi:10.1007/s11606-011-1901-8 pmid:21971601 pmcid:PMC3235605 fatcat:aru7kbhn3fcdneuwguw3fyym3q

Page 4178 of Psychological Abstracts Vol. 88, Issue 10 [page]

2001 Psychological Abstracts  
., 31190 Brady, Jacqueline, 30076 Brady, Joan Laidig, 31142 Brady, Michael K., 32136 Brady, Susan, 30832 Braff, D.  ...  Douglas, 29356 Bremner, Sandy, 31077 Brems, Christiane, 31763 Brendel, Johnston M.. 31807 Brendgen, Mara, 30183 Brenes, Abelardo, 29954, 32174 Brennan, Mark, 31065 Bretherton, Karen, 31531 Bretherton,  ... 
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