Tal G. Malkin
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Anna Lysyanskaya Curriculum Vitae
Anna Lysyanskaya Curriculum Vitae Computer Science Department, Box 1910 Brown University Providence, RI 02912 (401) 863-7605 email: [email protected] http://www.cs.brown.edu/~anna Research Interests Cryptography, privacy, computer security, theory of computation. Education Massachusetts Institute of Technology Cambridge, MA Ph.D. in Computer Science, September 2002 Advisor: Ronald L. Rivest, Viterbi Professor of EECS Thesis title: \Signature Schemes and Applications to Cryptographic Protocol Design" Massachusetts Institute of Technology Cambridge, MA S.M. in Computer Science, June 1999 Smith College Northampton, MA A.B. magna cum laude, Highest Honors, Phi Beta Kappa, May 1997 Appointments Brown University, Providence, RI Fall 2013 - Present Professor of Computer Science Brown University, Providence, RI Fall 2008 - Spring 2013 Associate Professor of Computer Science Brown University, Providence, RI Fall 2002 - Spring 2008 Assistant Professor of Computer Science UCLA, Los Angeles, CA Fall 2006 Visiting Scientist at the Institute for Pure and Applied Mathematics (IPAM) Weizmann Institute, Rehovot, Israel Spring 2006 Visiting Scientist Massachusetts Institute of Technology, Cambridge, MA 1997 { 2002 Graduate student IBM T. J. Watson Research Laboratory, Hawthorne, NY Summer 2001 Summer Researcher IBM Z¨urich Research Laboratory, R¨uschlikon, Switzerland Summers 1999, 2000 Summer Researcher 1 Teaching Brown University, Providence, RI Spring 2008, 2011, 2015, 2017, 2019; Fall 2012 Instructor for \CS 259: Advanced Topics in Cryptography," a seminar course for graduate students. Brown University, Providence, RI Spring 2012 Instructor for \CS 256: Advanced Complexity Theory," a graduate-level complexity theory course. Brown University, Providence, RI Fall 2003,2004,2005,2010,2011 Spring 2007, 2009,2013,2014,2016,2018 Instructor for \CS151: Introduction to Cryptography and Computer Security." Brown University, Providence, RI Fall 2016, 2018 Instructor for \CS 101: Theory of Computation," a core course for CS concentrators. -
Malicious Cryptography: Kleptographic Aspects
Malicious Cryptography: Kleptographic Aspects Adam Young1 and Moti Yung2 1 Cigital Labs [email protected] 2 Dept. of Computer Science, Columbia University [email protected] Abstract. In the last few years we have concentrated our research ef- forts on new threats to the computing infrastructure that are the result of combining malicious software (malware) technology with modern cryp- tography. At some point during our investigation we ended up asking ourselves the following question: what if the malware (i.e., Trojan horse) resides within a cryptographic system itself? This led us to realize that in certain scenarios of black box cryptography (namely, when the code is inaccessible to scrutiny as in the case of tamper proof cryptosystems or when no one cares enough to scrutinize the code) there are attacks that employ cryptography itself against cryptographic systems in such a way that the attack possesses unique properties (i.e., special advantages that attackers have such as granting the attacker exclusive access to crucial information where the exclusive access privelege holds even if the Trojan is reverse-engineered). We called the art of designing this set of attacks “kleptography.” In this paper we demonstrate the power of kleptography by illustrating a carefully designed attack against RSA key generation. Keywords: RSA, Rabin, public key cryptography, SETUP, kleptogra- phy, random oracle, security threats, attacks, malicious cryptography. 1 Introduction Robust backdoor attacks against cryptosystems have received the attention of the cryptographic research community, but to this day have not influenced in- dustry standards and as a result the industry is not as prepared for them as it could be. -
Arxiv:2102.09041V3 [Cs.DC] 4 Jun 2021
Reaching Consensus for Asynchronous Distributed Key Generation ITTAI ABRAHAM, VMware Research, Israel PHILIPP JOVANOVIC, University College London, United Kingdom MARY MALLER, Ethereum Foundation, United Kingdom SARAH MEIKLEJOHN, University College London, United Kingdom and Google, United Kingdom GILAD STERN, The Hebrew University in Jerusalem, Israel ALIN TOMESCU, VMware Research, USA < = We give a protocol for Asynchronous Distributed Key Generation (A-DKG) that is optimally resilient (can withstand 5 3 faulty parties), has a constant expected number of rounds, has $˜ (=3) expected communication complexity, and assumes only the existence of a PKI. Prior to our work, the best A-DKG protocols required Ω(=) expected number of rounds, and Ω(=4) expected communication. Our A-DKG protocol relies on several building blocks that are of independent interest. We define and design a Proposal Election (PE) protocol that allows parties to retrospectively agree on a valid proposal after enough proposals have been sent from different parties. With constant probability the elected proposal was proposed by a nonfaulty party. In building our PE protocol, we design a Verifiable Gather protocol which allows parties to communicate which proposals they have and have not seen in a verifiable manner. The final building block to our A-DKG is a Validated Asynchronous Byzantine Agreement (VABA) protocol. We use our PE protocol to construct a VABA protocol that does not require leaders or an asynchronous DKG setup. Our VABA protocol can be used more generally when it is not possible to use threshold signatures. 1 INTRODUCTION In this work we study Decentralized Key Generation in the Asynchronous setting (A-DKG). -
Chapter 2: an Implementation of Cryptoviral Extortion Using Microsoft's Crypto API∗
Chapter 2: An Implementation of Cryptoviral Extortion Using Microsoft's Crypto API∗ Adam L. Young and Moti M. Yung Abstract This chapter presents an experimental implementation of cryptovi- ral extortion, an attack that we devised and presented at the 1996 IEEE Symposium on Security & Privacy [16] and that was recently covered in Malicious Cryptography [17]. The design is based on Mi- crosoft's Cryptographic API and the salient aspects of the implemen- tation were presented at ISC '05 [14] and were later refined in the International Journal of Information Security [15]. Cryptoviral extor- tion is a 2-party protocol between an attacker and a victim that is carried out by a cryptovirus, cryptoworm, or cryptotrojan. In a cryp- toviral extortion attack the malware hybrid encrypts the plaintext of the victim using the public key of the attacker. The attacker extorts some form of payment from the victim in return for the plaintext that is held hostage. In addition to providing hands-on experience with this cryptographic protocol, this chapter gives readers a chance to: (1) learn the basics of hybrid encryption that is commonly used in every- thing from secure e-mail applications to secure socket connections, and (2) gain a basic understanding of how to use Microsoft's Cryptographic API that is present in modern MS Windows operating systems. The chapter only provides an experimental version of the payload, no self- replicating code is given. We conclude with proactive measures that can be taken by computer users and computer manufacturers alike to minimize the threat posed by this type of cryptovirology attack. -
Cyber Security Cryptography and Machine Learning
Lecture Notes in Computer Science 12716 Founding Editors Gerhard Goos Karlsruhe Institute of Technology, Karlsruhe, Germany Juris Hartmanis Cornell University, Ithaca, NY, USA Editorial Board Members Elisa Bertino Purdue University, West Lafayette, IN, USA Wen Gao Peking University, Beijing, China Bernhard Steffen TU Dortmund University, Dortmund, Germany Gerhard Woeginger RWTH Aachen, Aachen, Germany Moti Yung Columbia University, New York, NY, USA More information about this subseries at http://www.springer.com/series/7410 Shlomi Dolev · Oded Margalit · Benny Pinkas · Alexander Schwarzmann (Eds.) Cyber Security Cryptography and Machine Learning 5th International Symposium, CSCML 2021 Be’er Sheva, Israel, July 8–9, 2021 Proceedings Editors Shlomi Dolev Oded Margalit Ben-Gurion University of the Negev Ben-Gurion University of the Negev Be’er Sheva, Israel Be’er Sheva, Israel Benny Pinkas Alexander Schwarzmann Bar-Ilan University Augusta University Tel Aviv, Israel Augusta, GA, USA ISSN 0302-9743 ISSN 1611-3349 (electronic) Lecture Notes in Computer Science ISBN 978-3-030-78085-2 ISBN 978-3-030-78086-9 (eBook) https://doi.org/10.1007/978-3-030-78086-9 LNCS Sublibrary: SL4 – Security and Cryptology © Springer Nature Switzerland AG 2021 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. -
CHURP: Dynamic-Committee Proactive Secret Sharing
CHURP: Dynamic-Committee Proactive Secret Sharing Sai Krishna Deepak Maram∗† Cornell Tech Fan Zhang∗† Lun Wang∗ Andrew Low∗ Cornell Tech UC Berkeley UC Berkeley Yupeng Zhang∗ Ari Juels∗ Dawn Song∗ Texas A&M Cornell Tech UC Berkeley ABSTRACT most important resources—money, identities [6], etc. Their loss has We introduce CHURP (CHUrn-Robust Proactive secret sharing). serious and often irreversible consequences. CHURP enables secure secret-sharing in dynamic settings, where the An estimated four million Bitcoin (today worth $14+ Billion) have committee of nodes storing a secret changes over time. Designed for vanished forever due to lost keys [69]. Many users thus store their blockchains, CHURP has lower communication complexity than pre- cryptocurrency with exchanges such as Coinbase, which holds at vious schemes: O¹nº on-chain and O¹n2º off-chain in the optimistic least 10% of all circulating Bitcoin [9]. Such centralized key storage case of no node failures. is also undesirable: It erodes the very decentralization that defines CHURP includes several technical innovations: An efficient new blockchain systems. proactivization scheme of independent interest, a technique (using An attractive alternative is secret sharing. In ¹t;nº-secret sharing, asymmetric bivariate polynomials) for efficiently changing secret- a committee of n nodes holds shares of a secret s—usually encoded sharing thresholds, and a hedge against setup failures in an efficient as P¹0º of a polynomial P¹xº [73]. An adversary must compromise polynomial commitment scheme. We also introduce a general new at least t +1 players to steal s, and at least n−t shares must be lost technique for inexpensive off-chain communication across the peer- to render s unrecoverable. -
Improved Threshold Signatures, Proactive Secret Sharing, and Input Certification from LSS Isomorphisms
Improved Threshold Signatures, Proactive Secret Sharing, and Input Certification from LSS Isomorphisms Diego F. Aranha1, Anders Dalskov2, Daniel Escudero1, and Claudio Orlandi1 1 Aarhus University, Denmark 2 Partisia, Denmark Abstract. In this paper we present a series of applications steming from a formal treatment of linear secret-sharing isomorphisms, which are linear transformations between different secret-sharing schemes defined over vector spaces over a field F and allow for efficient multiparty conversion from one secret-sharing scheme to the other. This concept generalizes the folklore idea that moving from a secret-sharing scheme over Fp to a secret sharing \in the exponent" can be done non-interactively by multiplying the share unto a generator of e.g., an elliptic curve group. We generalize this idea and show that it can also be used to compute arbitrary bilinear maps and in particular pairings over elliptic curves. We include the following practical applications originating from our framework: First we show how to securely realize the Pointcheval-Sanders signature scheme (CT-RSA 2016) in MPC. Second we present a construc- tion for dynamic proactive secret-sharing which outperforms the current state of the art from CCS 2019. Third we present a construction for MPC input certification using digital signatures that we show experimentally to outperform the previous best solution in this area. 1 Introduction A(t; n)-secure secret-sharing scheme allows a secret to be distributed into n shares in such a way that any set of at most t shares are independent of the secret, but any set of at least t + 1 shares together can completely reconstruct the secret. -
Cryptography Abstracts
Cryptography Abstracts Saturday 10:15 – 12:15 Shafi Goldwasser, MIT Anna Lysyanskaya, Brown University Alice Silverberg, University of California, Irvine Nadia Heninger, UCSD Sunday 8:30 – 10:30 Tal Rabin, IBM Research Tal Malkin, Columbia University Allison Bishop Lewko, University of Texas, Austin Yael Tauman-Kalai, Microsoft Research – New England Saturday 10:15 – 12:15 On Probabilistic Proofs Shafi Goldwasser, MIT ABSTRACT Flavors and applications of verifiable random functions Anna Lysyanskaya, Brown University A random Boolean function is a function where for every input x, the value f(x) is truly random. A pseudorandom function is one where, even though f(x) can be deterministically computed from a small random "seed" s, no efficient algorithm can distinguish f from a random function upon querying it on inputs x1,...,xn of its choice. A verifiable random function (VRF) is a pseudorandom function that can be verified. That is to say, a VRF consists of four algorithms: Generate, Evaluate, Prove, Verify. Alice chooses uses Generate to pick her function f, Evaluate to evaluate it and compute y=f(x), Prove in order to compute a proof p(x) that y is indeed f(x). Bob can then use Verify in order to ascertain that it is indeed the case that y=f(x). At the same time, whenever Bob is not given a proof p(x) for a particular x, no efficient algorithm allows him to determine whether y=f(x) or is random. In this talk I will give a survey of verifiable random functions and their constructions and applications. Elliptic Curve Primality Tests for Numbers in Special Forms Alice Silverberg, University of California, Irvine In joint work with Alex Abatzoglou and Angela Wong, we use elliptic curves with complex multiplication to give primality proofs for integers of certain forms, generalizing earlier work of B. -
Speeding-Up Verification of Digital Signatures Abdul Rahman Taleb, Damien Vergnaud
Speeding-Up Verification of Digital Signatures Abdul Rahman Taleb, Damien Vergnaud To cite this version: Abdul Rahman Taleb, Damien Vergnaud. Speeding-Up Verification of Digital Signatures. Journal of Computer and System Sciences, Elsevier, 2021, 116, pp.22-39. 10.1016/j.jcss.2020.08.005. hal- 02934136 HAL Id: hal-02934136 https://hal.archives-ouvertes.fr/hal-02934136 Submitted on 27 Sep 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Speeding-Up Verification of Digital Signatures Abdul Rahman Taleb1, Damien Vergnaud2, Abstract In 2003, Fischlin introduced the concept of progressive verification in cryptog- raphy to relate the error probability of a cryptographic verification procedure to its running time. It ensures that the verifier confidence in the validity of a verification procedure grows with the work it invests in the computation. Le, Kelkar and Kate recently revisited this approach for digital signatures and pro- posed a similar framework under the name of flexible signatures. We propose efficient probabilistic verification procedures for popular signature schemes in which the error probability of a verifier decreases exponentially with the ver- ifier running time. We propose theoretical schemes for the RSA and ECDSA signatures based on some elegant idea proposed by Bernstein in 2000 and some additional tricks. -
September 21-23, 2021 Women in Security and Cryptography Workshop
September 21-23, 2021 Women in Security and Cryptography Workshop Our WISC- Speakers Our WISC-Speakers Adrienne Porter Felt, Google BIO. Adrienne is a Director of Engineering at Google, where she leads Chrome’s Data Science, content ecosystem, and iOS teams. Previously, Adrienne founded and led Chrome’s usable security team. She is best known externally for her work on moving the web to HTTPS, earning her recognition as one of MIT Technology Review’s Innovators Under 35. Adrienne holds a PhD from UC Berkeley, and most of her academic publications are on usable security for browsers and mobile operating systems. Copyright: Adrienne Porter Felt Carmela Troncoso, École polytechnique fédérale de Lausanne BIO. Carmela Troncoso is an assistant professor at EPFL, Switzerland, where she heads the SPRING Lab. Her work focuses on analyzing, building, and deploying secure and privacy-preserving systems. Carmela holds a PhD in Engineering from KULeuven. Her thesis, Design and Analysis Methods for Privacy Technologies, received the European Research Consortium for Informatics and Mathematics Security and Trust Management Best PhD Thesis Award, and her work on Privacy Engineering received the CNIL-INRIA Privacy Protection Award in 2017. She has been named 40 under 40 in technology by Fortune in 2020. Copyright: Carmela Troncoso Elette Boyle, IDC Herzliya BIO. Elette Boyle is an Associate Professor, and Director of the FACT (Foundations & Applications of Cryptographic Theory) Research Center, at IDC Herzliya, Israel. She received her PhD from MIT, and served as a postdoctoral researcher at Cornell University and at the Technion Israel. Elette's research focuses on secure multi- party computation, secret sharing, and distributed algorithm design. -
Cryptovirology: Extortion-Based Security Threats and Countermeasures
Crypt ovirology : Extortion-Based Security Threats and Countermeasures* Adam Young Moti Yung Dept. of Computer Science, IBM T.J. Wi3tson Research Center Columbia University. Yorktown Heights, NY 1.0598. Abstract atomic fission is to energy production), because it al- lows people to store information securely and to con- Traditionally, cryptography and its applications are duct private communications over large distances. It defensive in nature, and provide privacy, authen tica- is therefore natural to ask, “What are the potential tion, and security to users. In this paper we present the harmful uses of Cryptograplhy?” We believe that it is idea of Cryptovirology which employs a twist on cryp- better to investigate this aspect rather than to wait tography, showing that it can also be used offensively. for such att,acks to occur. In this paper we attempt By being offensive we mean that it can be used to a first step in this directioin by presenting a set of mount extortion based attacks that cause loss of access cryptographiy-exploiting computer security attacks and to information, loss of confidentiality, and inform,ation potential countermeasures. leakage, tasks which cryptography typically prevents. In this paper we analyze potential threats and attacks The set of attacks that we present involve the that rogue use of cryptography can cause when com- unique use of strong (public key and symmetric) cryp- tographic techniques in conjunction with computer bined with rogue software (viruses, Trojan horses), and virus and Trojan horse technology. They demon- demonstrate them experimentally by presenting an im- strate how cryptography (namely, difference in com- plementation of a cryptovirus that we have tested (we putational capability) can allow an adversarial virus took careful precautions in the process to insure that writer to gain explicit access control over the data the virus remained contained). -
Program of the NIST Workshop on Multi-Party Threshold Schemes MPTS 2020 — Virtual Event (November 4–6, 2020)
MPTS 2020 program (updated November 20, 2020) Program of the NIST Workshop on Multi-Party Threshold Schemes MPTS 2020 — Virtual event (November 4–6, 2020) https://csrc.nist.gov/events/2020/mpts2020 # Hour Speaker(s) Topic (not the title) — 09:15–09:35 — Virtual arrival 1a1 09:35–10:00 Luís Brandão Workshop introduction 1a2 10:00–10:25 Berry Schoenmakers Publicly verifiable secret sharing Talks 1a3 10:25–10:50 Ivan Damgård Active security with honest majority — 10:50–11:05 — Break 1b1 11:05–11:30 Tal Rabin MPC in the YOSO model 1b2 11:30–11:55 Nigel Smart Threshold HashEdDSA (deterministic) Talks 1b3 11:55–12:20 Chelsea Komlo Threshold Schnorr (probabilistic) November 4 — 12:20–12:30 — Break 1c1 12:30–12:36 Yashvanth Kondi Threshold Schnorr (deterministic) 1c2 12:36–12:42 Akira Takahashi PQ Threshold signatures 1c3 12:42–12:48 Jan Willemson PQ Threshold schemes Briefs 1c4 12:48–12:54 Saikrishna Badrinarayanan Threshold bio-authentication — 12:54–13:00+ — Day closing — 09:15–09:35 — Virtual arrival 2a1 09:35–10:00 Yehuda Lindell Diverse multiparty settings 2a2 10:00–10:25 Ran Canetti General principles (composability, ...) Talks 2a3 10:25–10:50 Yuval Ishai Pseudorandom correlation generators — 10:50–11:05 — Break 2b1 11:05–11:30 Emmanuela Orsini & Peter Scholl Oblivious transfer extension 2b2 11:30–11:55 Vladimir Kolesnikov Garbled circuits Talks 2b3 11:55–12:20 Xiao Wang Global scale threshold AES — 12:20–12:30 — Break November 5 2c1 12:30–12:36 Xiao Wang Garbled circuits 2c2 12:36–12:42 Jakob Pagter MPC-based Key-management 2c3 12:42–12:48