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02 April 2019
Łukasz Krzywiecki, Mirosław Kutyłowski, Jakub Pezda, Marcin Słowik
Eli Ben-Sasson, Lior Goldberg, Swastik Kopparty, Shubhangi Saraf
Yan Yan, Elisabeth Oswald
Abdelrahaman Aly, Aysajan Abidin, Svetla Nikova
Helger Lipmaa
Benjamin Hong Meng Tan, Hyung Tae Lee, Huaxiong Wang, Shu Qin Ren, Khin Mi Mi Aung
In this work, we design efficient private database query (PDQ) protocols which support order comparisons and compound conditions. To this end, we first present a private comparison algorithm on encrypted integers using FHE, which scales efficiently for the length of input integers, by applying techniques from finite field theory. Then, we consider two scenarios for PDQ protocols, the first for retrieving data based on one order comparison and the second based on a conjunction of one order and four equality conditions. The proposed algorithm and protocols are implemented and tested to determine their performance in practice. The proposed comparison algorithm takes about 20.155 seconds to compare 697 pairs of 64-bit integers using Brakerski-Gentry-Vaikuntanathan's leveled FHE scheme with single instruction multiple data (SIMD) techniques at more than 110 bits of security. This yields an amortized rate of just 29 milliseconds per comparison. On top of that, we show that our techniques achieve an efficient PDQ protocol for one order and four equality comparisons, achieving an amortized time and communication cost of 36 milliseconds and 154 bytes per database element.
Amir Jalali, Reza Azarderakhsh, Mehran Mozaffari Kermani, Matthew Campagna, David Jao
Reza Azarderakhsh, Amir Jalali, David Jao, Vladimir Soukharev
30 March 2019
Mohammad Mahmoody, Tal Moran, Salil Vadhan
Our construction is secure in the standard model under complexity assumptions (collision-resistant hash functions and inherently sequential hash functions), and makes black-box use of the underlying primitives. Consequently, the corresponding construction in the random oracle model is secure unconditionally. Moreover, as it is a public-coin protocol, it can be made non-interactive in the random oracle model using the Fiat-Shamir Heuristic.
Our construction makes a novel use of ``depth-robust'' directed acyclic graphs---ones whose depth remains large even after removing a constant fraction of vertices---which were previously studied for the purpose of complexity lower bounds. The construction bypasses a recent negative result of Mahmoody, Moran, and Vadhan (CRYPTO `11) for time-lock puzzles in the random oracle model, which showed that it is impossible to have time-lock puzzles like ours in the random oracle model if the puzzle generator also computes a solution together with the puzzle.
Boaz Barak, Mohammad Mahmoody
Our result extends (with a loss of a constant factor in the number of queries) also to the random permutation and ideal-cipher oracles. Since the symmetric primitives (e.g. block ciphers, hash functions, and message authentication codes) can be constructed by a constant number of queries to the mentioned oracles, as corollary we get lower bounds on the efficiency of signature schemes from symmetric primitives when the construction is black-box. This can be taken as evidence of an inherent efficiency gap between signature schemes and symmetric primitives.
29 March 2019
University of Luxembourg, Cryptolux (SnT)
The successful candidate will join the CryptoLUX group led by Prof. Alex Biryukov. Candidates with proven research track record in one or more of the following areas are particularly encouraged to apply:
- Design/analysis of lightweight crypto (with the goal to evaluate NIST competition submissions)
- Financial cryptography (cryptocurrencies, blockchain tech)
- Privacy enhancing technologies
Your Profile
A Ph.D. degree in Computer Science, Applied Mathematics or a related field; Competitive research record in applied cryptography or information security (at least one paper in top 10 IT security/crypto conferences; or several papers at ToSC(FSE), CHES, PETs or TCC); Strong mathematical and algorithmic CS background; Good skills in programming and scripting languages; Commitment, team working and a critical mind; Fluent written and verbal communication skills in English are mandatory.
The University offers a one years employment contract (with extension possibility). The University offers highly competitive salaries and is an equal opportunity employer. You will work in an exciting international environment of a large IT security-focused research center (SnT/CSC), developing technologies which will have direct impact on the future.
Applications, written in English, should be submitted by e-mail and should include:
- A brief cover letter explaining the candidate\'s motivation and research interests
- Curriculum Vitae (including photo, education/research/ work, publications, interests)
- Information on participation in competitions, Olympiads, CTFs is a plus
- Contact information of 2-3 references
Applications will be considered on receipt therefore applying before the deadline is encouraged.
Closing date for applications: 1 May 2019
Contact: Prof. Alex Biryukov
More information: https://www.cryptolux.org/index.php/Vacancies
Society for Electronic Transactions and Security [SETS], Chennai, India
Post: Project Associate (Number of Posts: 2)
Project Duration: 3 years (the positions as proposed are purely temporary and would be filled on Contract basis with consolidated salary under the project). The appointment will be made initially for a period of two years and extendable upto further one more year or the closing date of the project whichever is earlier.
Salary: Rs 40,000 to Rs 50,000 per month commensurate to relevant experience
Essential Qualifications: M.E/M.Tech in Electronics and Communication Engineering/ Computer Science and Engineering/ Applied Electronics/ Embedded Systems/ VLSI Design from a recognized university in First Class with 60% or above marks or equivalent.
Areas of Skill sets/ Knowledge required:
a) Knowledge in cryptology and strong background in digital system design, including project development experience in C, MATLAB, VHDL/Verilog programming. b) In-depth knowledge of front-end digital design process and related design flows (Xilinx FPGA /ASIC digital IC design). c) Candidates with prior industrial/research experience in the field of Hardware Security including Physical Unclonable Function (PUF) and Side Channel Attacks (SCA) are preferred.
Selection Procedure: Written Test and/or Interview
How to Apply?
1) Applications received via email will ONLY be considered. Candidate should write “Application for Project Associate Position” in the subject line of his/her E-mail. 2) The candidate is required to attach the Personal Particulars Form in pdf format duly filled and signed. 3) The email should be sent to hrpuf2019 (at) setsindia.net
Closing date for applications: 10 April 2019
Contact: N. Nalla Anandakumar, Scientist, SETS (Co-Principal Investigator)
More information: https://setsindia.in/careers
Estuardo Alpirez Bock, Alessandro Amadori, Joppe W. Bos, Chris Brzuska, Wil Michiels
Jordi Herrera-Joancomartí, Guillermo Navarro-Arribas, Alejandro Ranchal-Pedrosa, Joaquín Garcia-Alfaro, Cristina Pérez-Solà
Gembu Ito, Tetsu Iwata
In this paper, we show a polynomial time quantum distinguishing attack against the $(3d-3)$-round version, i.e., we improve the number of rounds by $(d-2)$. We also show a quantum distinguishing attack against the $(d^2-d+1)$-round version in the quantum chosen-ciphertext setting. We apply these quantum distinguishing attacks to obtain key recovery attacks against Type-1 generalized Feistel ciphers.
Alonso González, Carla Ràfols
An additional contribution of the paper is to obtain a very efficient argument for verifiable computation using the same design principles which is based on weaker assumptions. The communication is approximately 4d group elements and verifying a proof requires computing around 4d pairings and O(n+d) exponentiations, where n is the input size and d the circuit depth. While the argument for the quadratic constraints is based on standard falsifiable assumptions, the argument for the linear constraints is based on a very ad-hoc assumption about certain properties of arguments of membership in linear spaces.