IACR News
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14 April 2017
Ethan Cecchetti, Fan Zhang, Yan Ji, Ahmed Kosba, Ari Juels, Elaine Shi
ePrint ReportIn this paper we present Solidus, a protocol for confidential transactions on public blockchains, such as those required for asset transfers with on-chain settlement. Solidus operates in a framework based on real-world financial institutions: a modest number of banks each maintain a large number of user accounts. Within this framework, Solidus hides both transaction values and the transaction graph (i.e., the identities of transacting entities) while maintaining the public verifiability that makes blockchains so appealing. To achieve strong confidentiality of this kind, we introduce the concept of a Publicly-Verifiable Oblivious RAM Machine (PVORM). We present a set of formal security definitions for both PVORM and Solidus and show that our constructions are secure. Finally, we implement Solidus and present a set of benchmarks indicating that the system is efficient in practice.
Yan Yan, Elisabeth Oswald, Theo Tryfonas
ePrint ReportBernardo Ferreira, Joaão Leitão, Henrique Domingos
ePrint ReportDaniel J. Bernstein, Tanja Lange
ePrint ReportPost-quantum cryptography is cryptography under the assumption that the attacker has a large quantum computer; post-quantum cryptosystems strive to remain secure even in this scenario. This relatively young research area has seen some successes in identifying mathematical operations for which quantum algorithms offer little speedup, and then building cryptographic systems around those. The central challenge in post-quantum cryptography is to meet demands for cryptographic usability and flexibility without sacrificing trust.
12 April 2017
National Institute of Technology Raipur
Job PostingClosing date for applications: 26 April 2017
Contact: Dr. T. Meenpal
Assistant Professor,
Electronics & Telecommunication Engineering
Department
NIT Raipur,Chhattisgarh- 492010
Email: tmeenpal.etc (at) nitrr.ac.in
More information: http://www.nitrr.ac.in/downloads/recruitment/recruitment2017/project_fellow/JRF_EnTC_advertisement_ETC_10042017.pdf
University of South Florida, Tampa, FL
Job PostingUSF is an R1 university and among the leading institutions in Florida. We are looking for motivated, talented, and hardworking applicants who have background and are interested in working on different aspects of Cryptographic Engineering with emphasis on:
- Cryptographic hardware systems
- Side-channel attacks, particularly fault and power analysis attacks
The required expertise includes:
- Masters (or Bachelors with outstanding background) in Computer Engineering or Electrical Engineering
- Solid background in digital design, VLSI, computer arithmetic, and ASIC/FPGA implementations
- Solid HDL expertise
- Outstanding English (if English tests are taken) to be eligible for department funding
- Motivation to work beyond the expectations from an average Ph.D. student and publish in top tier venues
Please closely observe the admission requirement details here before emailing:
http://www.usf.edu/engineering/cse/graduate/phd-program.aspx
Please send me your updated CV (including list of publications, language test marks, and references), transcripts for B.Sc. (and M.Sc.), and a statement of interest at usfcrypto2017 (at) gmail.com as soon as possible.
NOTE: At this time, I consider only the applicants who have already taken TOEFL/IELTS and GRE exams with excellent marks. The successful candidate will be asked to apply formally very soon to the USF CSE department, so all the material has to be already ready.
Closing date for applications: 20 April 2017
University of Bergen, Norway
Job PostingFor further information and for application for the position see the webpage:
https://www.jobbnorge.no/en/available-jobs/job/137029/phd-position-in-boolean-functions
Closing date for applications: 15 May 2017
Contact: Dr. Lilya Budaghyan lilya.budaghyan (at) uib.no
University of Tartu
Job PostingWe are starting a project in which we will develop methods for the verification of proofs in quantum cryptography. Similar to what the EasyCrypt tool does in classical cryptography. The scope of the project covers everything from the logical foundations, through the development of tools, to the verification of real quantum protocols.
The ideal candidate would have experience in:
- Semantics
- Theorem proving
- Verification of classical cryptography
- Quantum cryptography
- Quantum computation / communication
Of course, expertise in all those areas is very rare, so candidates who are strong in some of those areas and are interested in the others are encouraged to apply!
Please contact Dominique Unruh if you have more questions about the project, the required background, Estonia, the position itself, or the application process.
The salary range is 30000-36000 Euro per year (depending on experience), which is highly competitive in Estonia due to low costs of living and low income tax rate (20%), pension contributions and health insurance are covered by the employer.
The position is for three years, September 1, 2017 till August 31, 2020. The starting date and duration can be negotiated (in both directions).
For application instructions, see the link below.
Closing date for applications: 1 June 2017
Contact: Dominique Unruh
Professor of Information Security
Department of Computer Science
University of Tartu
unruh (at) ut.ee
More information: http://crypto.cs.ut.ee/Main/PostdocInVerificationOfQuantumCryptography
11 April 2017
Yanqing Yao, Hua Guo, Zhoujun Li
ePrint ReportBoaz Barak, Zvika Brakerski, Ilan Komargodski, Pravesh K. Kothari
ePrint ReportIn particular, if $G\colon\{0,1\}^n \rightarrow \{0,1\}^m$ and $m$ is as above, then $G$ cannot be a pseudorandom generator. Our algorithm is based on semidefinite programming and in particular the sum of squares (SOS) hierarchy.
As a corollary, we refute some conjectures recently made in the cryptographic literature. This includes refuting the assumptions underlying Lin and Tessaro's recently proposed candidate construction for indistinguishability obfuscation from bilinear maps, by showing that any block-wise 2-local PRG with block size $b$ cannot go beyond $m \approx 2^{2b}\cdot n$. We give an even stronger bound of $m \approx 2^b n$ on the output length of random block-wise 2-local PRGs. We also show that a generalized notion of generators runs into similar barriers.
We complement our algorithm by presenting a class of candidate generators with block-wise locality $3$ and constant block size, that resists both Gaussian elimination and SOS algorithms whenever $m = n^{1.5-\varepsilon}$. This class is extremely easy to describe: Let $\mathbb{G}$ be any simple non-abelian group, and interpret the blocks of $x$ as elements in $\mathbb{G}$, then each output of the generator is of the form $x_i \ast x_j \ast x_k$, where $i,j,k$ are random and "$\ast$" is the group operation.
Aaron Hutchinson, Koray Karabina
ePrint ReportShuai Han, Shengli Liu
ePrint ReportIn this paper, we present the first PKE with KDM-security based on constant-noise LPN, where the number of users is predefined. The technical tool is two types of _multi-fold LPN on squared-log entropy_, one having _independent secrets_ and the other _independent sample subspaces_. We establish the hardness of the multi-fold LPN variants on constant-noise LPN. Two squared-logarithmic entropy sources for multi-fold LPN are carefully chosen, so that our PKE is able to achieve correctness and KDM-security simultaneously.
Maiki Fujita, Takeshi Koshiba
ePrint Report10 April 2017
Eurocrypt
Nicholas Genise, Daniele Micciancio
ePrint ReportLing Ren, Kartik Nayak, Ittai Abraham, Srinivas Devadas
ePrint ReportYosuke Todo, Takanori Isobe, Yonglin Hao, Willi Meier
ePrint ReportAlessandro Chiesa, Michael A. Forbes, Nicholas Spooner
ePrint ReportIn this work, we develop algebraic techniques for obtaining zero knowledge variants of proof protocols in a way that leverages and preserves their algebraic structure. Our constructions achieve unconditional (perfect) zero knowledge in the Interactive Probabilistically Checkable Proof (IPCP) model of Kalai and Raz [KR08] (the prover first sends a PCP oracle, then the prover and verifier engage in an Interactive Proof in which the verifier may query the PCP).
Our main result is a zero knowledge variant of the sumcheck protocol [LFKN92] in the IPCP model. The sumcheck protocol is a key building block in many IPs, including the protocol for polynomial-space computation due to Shamir [Sha92], and the protocol for parallel computation due to Goldwasser, Kalai, and Rothblum [GKR15]. A core component of our result is an algebraic commitment scheme, whose hiding property is guaranteed by algebraic query complexity lower bounds [AW09,JKRS09]. This commitment scheme can then be used to considerably strengthen our previous work [BCFGRS16] that gives a sumcheck protocol with much weaker zero knowledge guarantees, itself using algebraic techniques based on algorithms for polynomial identity testing [RS05,BW04].
We demonstrate the applicability of our techniques by deriving zero knowledge variants of well-known protocols based on algebraic techniques. First, we construct zero knowledge IPCPs for NEXP starting with the Multi-prover Interactive Proofs of Babai, Fortnow, and Lund [BFL91]. This result is a direct application of our zero knowledge sumcheck and our algebraic commitment scheme, augmented with the use of `randomized' low-degree extensions.
We also construct protocols in a more restricted model where the prover and verifier engage in a standard Interactive Proof with oracle access to a uniformly random low-degree polynomial (soundness holds with respect to any oracle). In this setting we achieve zero knowledge variants of the protocols of Shamir and of Goldwasser, Kalai, and Rothblum.
Yang Yu, Guangwu Xu, Xiaoyun Wang
ePrint ReportDana Dachman-Soled, Mukul Kulkarni, Aria Shahverdi
ePrint ReportThe bounded retrieval model (BRM) (cf. [Alwen et al., CRYPTO '09] and [Alwen et al., EUROCRYPT '10]) has been studied extensively in the setting of leakage resilience for cryptographic primitives. This threat model assumes that an attacker can learn information about the secret key, subject only to the constraint that the overall amount of leaked information is upper bounded by some value. The goal is then to construct cryptosystems whose secret key length grows with the amount of leakage, but whose runtime (assuming random access to the secret key) is independent of the leakage amount.
In this work, we combine the above two notions and construct locally decodable and updatable non-malleable codes in the split-state model, that are secure against bounded retrieval adversaries. Specifically, given leakage parameter l, we show how to construct an efficient, 3-split-state, locally decodable and updatable code (with CRS) that is secure against one-time leakage of any polynomial time, 3-split-state leakage function whose output length is at most l, and one-time tampering via any polynomial-time 3-split-state tampering function. The locality we achieve is polylogarithmic in the security parameter.