International Association for Cryptologic Research

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03:17 [Pub][ePrint] Improved Timing Attacks on ECDSA, by Vikram Singh

  We improve the timing attack on ECDSA in [1] by Brumley and Tuveri. We use the Gaussian heuristic to analyse the length of error vectors in the lattice Close Vector Problem in order to determine the problems which are theoretically solvable. Then we cost each solution using a strengthened lattice reduction algorithm and Schnorr-Euchner enumeration to determine which problems are practically solvable. The original work by Brumley and Tuveri resulted in OpenSSL\'s ECDSA being updated to remove the timing information they exploited, so that application is not vulnerable to our improvements. However we publish this work as a general advance in side-channel recovery techniques which may be applicable in related scenarios.

03:17 [Pub][ePrint] Generic Hardness of the Multiple Discrete Logarithm Problem, by Aaram Yun

  We study generic hardness of the multiple discrete logarithm problem, where the solver has to solve $n$ instances of the discrete logarithm problem simultaneously. There are known generic algorithms which perform $O(\\sqrt{n p})$ group operations, where $p$ is the group order, but no generic lower bound was known other than the trivial bound. In this paper we prove the tight generic lower bound, showing that the previously known algorithms are asymptotically optimal. We establish the lower bound by studying hardness of a related computational problem which we call the search-by-hyperplane-queries problem.

03:17 [Pub][ePrint] Pattern Matching Encryption, by Melissa Chase and Emily Shen

  In this paper, we consider a setting where a user wants to outsource storage of a large amount of private data, and then perform pattern matching queries on the data; that is, given a data string $s$ and a

``pattern\'\' string $p$, find all occurrences of $p$ as a substring of $s$.

We formalize the security properties desired in this type of setting by defining a type of encryption called \\emph{queryable

encryption}. In a queryable encryption scheme, a user can encrypt a

message $M$ under a secret key, and using the secret key can

generate tokens for queries $q$. Applying a token for a query $q$

to an encryption of $M$ gives the answer to the query $q$ on $M$. We consider security against both honest-but-curious and malicious adversaries, and define properties guaranteeing both the correctness of the user\'s results and the privacy of the user\'s data. Following the line of work started by \\cite{CGKO06}, to allow for efficient constructions, we allow the protocol to leak some information about the user\'s data, however we ensure that this leakage can be precisely captured in the definition. In addition, we allow the query protocol to involve a small constant number of rounds of interaction.

We construct a queryable encryption scheme for pattern matching queries that is correct and secure in the malicious model. Our construction is based on efficient symmetric-key building blocks and scales well with the size of the input: encryption of a data string of length $n$ with security parameter $\\lambda$ takes $O(n)$ time and produces a ciphertext of size $O(n\\lambda)$, and a query for a pattern string of length $m$ that occurs $k$ times takes $O(m+k)$ time and three rounds of communication.

03:17 [Pub][ePrint] Automated Design, Implementation, and Evaluation of Arbiter-based PUF on FPGA using Programmable Delay Lines, by Mehrdad Majzoobi, Akshat Kharaya, Farinaz Koushanfar, Srinivas Devadas

  This paper proposes a novel approach for automated implementation of an arbiter-based physical unclonable function (PUF)

on field programmable gate arrays (FPGAs). We introduce a high resolution programmable delay logic (PDL) that is implemented

by harnessing the FPGA lookup-table (LUT) internal structure. PDL allows automatic fine tuning of delays that

can mitigate the timing skews caused by asymmetries in interconnect routing and systematic variations. To thwart the arbiter metastability problem, we present and analyze methods for majority voting of responses. A method to classify and group challenges into different robustness sets is introduced that enhances the corresponding responses\' stability in the face of operational variations. The trade-off between response stability and response entropy (uniqueness) is investigated through comprehensive measurements. We exploit the correlation between the impact of temperature and power supply on responses and perform less costly power measurements to predict the temperature impact on PUF. The measurements are performed on 12 identical Virtex 5 FPGAs across 9 different accurately controlled operating temperature and voltage supply points. A database of challenge response pairs (CRPs) are collected and made openly available for the research community.

23:42 [Election] IACR 2014 Election: Nominations open


IACR 2014 Election

The 2014 election is being held to fill three of nine IACR Director positions. The election will again be run electronically and further information will be available on the IACR website.

Nominations Are Now Open

Nominations are due by October 10, 2014. A nomination form is available at the elections page.

Election of Directors

The directors whose terms are expiring are
  • Josh Benaloh (director)
  • Shai Halevi (director)
  • Moti Yung (director)

Election Committee

  • Michel Abdalla (Returning Officer)
  • Anna Lysyanskaya
  • Bart Preneel (Chair)

21:17 [Pub][ePrint] Get Your Hands Off My Laptop: Physical Side-Channel Key-Extraction Attacks on PCs, by Daniel Genkin and Itamar Pipman and Eran Tromer

  We demonstrate physical side-channel attacks on a popular software implementation of RSA and ElGamal, running on laptop computers. Our attacks use novel side channels, based on the observation that the \"ground\" electric potential, in many computers, fluctuates in a computation-dependent way. An attacker can measure this signal by touching exposed metal on the computer\'s chassis with a plain wire, or even with a bare hand. The signal can also be measured at the remote end of Ethernet, VGA or USB cables.

Through suitable cryptanalysis and signal processing, we have extracted 4096-bit RSA keys and 3072-bit ElGamal keys from laptops, via each of these channels, as well as via power analysis and electromagnetic probing. Despite the GHz-scale clock rate of the laptops and numerous noise sources, the full attacks require a few seconds of measurements using Medium Frequency signals (around 2 MHz), or one hour using Low Frequency signals (up to 40 kHz).

21:17 [Pub][ePrint] On Modes of Operations of a Block Cipher for Authentication and Authenticated Encryption, by Debrup Chakraborty and Palash Sarkar

  This work deals with the various requirements of encryption and authentication in cryptographic applications. The approach

is to construct suitable modes of operations of a block cipher to achieve the relevant goals. A variety

of schemes suitable for specific applications are presented. While none of the schemes are built completely from scratch,

there is a common unifying framework which connects them. All the schemes described have been implemented and the implementation

details are publicly available. Performance figures are presented when the block cipher is the AES and the Intel AES-NI

instructions are used. These figures suggest that the constructions presented here compare well with previous works

such as the famous OCB mode of operation. In terms of features, the constructions provide several new offerings which

are not present in earlier works. This work significantly widens the range of choices of an actual designer of

cryptographic system.

21:17 [Pub][ePrint] An Efficient $t$-Cheater Identifiable Secret Sharing Scheme with Optimal Cheater Resiliency, by Partha Sarathi Roy and Avishek Adhikari and Rui Xu and Kirill Morozov and Kouichi Sakurai

  In this paper, we present an efficient $k$-out-of-$n$ secret sharing scheme, which can identify up to $t$ rushing cheaters, with probability at least $1 - \\epsilon$, where $0

21:17 [Pub][ePrint] Realizing two-factor authentication for the Bitcoin protocol, by Christopher Mann and Daniel Loebenberger

  We show how to realize two-factor authentication for a Bitcoin wallet employing the two-party ECDSA signature protocol adapted from MacKenzie & Reiter (2004). We also present a prototypic implementation of a Bitcoin wallet that offers both: two-factor authentication and verification over a separate channel. Since we use a smart phone as the second authentication factor, our solution can be used with hardware already available to most users and the user experience is quite similar to the existing online banking authentication methods.

21:17 [Pub][ePrint] Efficient Oblivious Parallel Array Reads and Writes for Secure Multiparty Computation, by Peeter Laud

  In this note we describe efficient protocols to perform in parallel many reads and writes in private arrays according to private indices. The protocol is implemented on top of the Arithmetic Black Box (ABB) and can be freely composed to build larger privacy-preserving applications. For a large class of secure multiparty computation (SMC) protocols, we believe our technique to have better practical performance than any previous ORAM technique that has been adapted for use in SMC. We also argue that for a significant class of SMC protocols, our technique has better asymptotic performance than previous approaches.

01:05 [Event][New] HOST '15: IEEE International Symposium on Hardware-Oriented Security and Trust

  Submission: 24 October 2014
Notification: 16 January 2015
From May 5 to May 7
Location: Washington DC Metro Area, USA
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