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2012-10-25
15:17 [Pub][ePrint]

We present new constructions of leakage-resilient cryptosystems, which remain provably secure even if the attacker learns some arbitrary partial information about their internal secret key. For any polynomial $\\ell$, we can instantiate these schemes so as to tolerate up to $\\ell$ bits of leakage. While there has been much prior work constructing such leakage-resilient cryptosystems under concrete number-theoretic and algebraic assumptions, we present the first schemes under general and minimal assumptions. In particular, we construct:

- Leakage-resilient public-key encryption from any standard public-key encryption.

- Leakage-resilient weak pseudorandom functions, symmetric-key encryption}, and message-authentication codes from any one-way function.

These are the first constructions of leakage-resilient symmetric-key primitives that do not rely on public-key assumptions. We also get the first constructions of leakage-resilient public-key encryption from search assumptions\'\', such as the hardness of factoring or CDH. Although our schemes can tolerate arbitrarily large amounts of leakage, the tolerated rate of leakage (defined as the ratio of leakage-amount to key-size) is rather poor in comparison to prior results under specific assumptions.

As a building block of independent interest, we study a notion of weak hash-proof systems in the public-key and symmetric-key settings. While these inherit some of the interesting security properties of standard hash-proof systems, we can instantiate them under general assumptions.

2012-10-23
12:35 [Event][New]

Submission: 20 November 2012
From March 25 to March 29
Location: Yogyakarta, Indonesia

05:41 [Job][New]

Job Duties:

• Model Cryptographic systems for adherence to specific requirements

• Interact with customers to address questions on impacts of implementation

• Provide guidance to program engineering teams on cryptographic implementation

• Supporting system engineers and designers in architecture trade-offs

Required Skills:

• Minimum of 10 years direct related experience with System Engineering Analysis and Development of Cryptographic Systems.

• Technical experience in developing complex software and/or hardware systems for cryptographic systems

• Demonstrated background in System Modeling, System Simulation, and/or Design of Experiments

• Experience architecting, designing, implementing, testing real-time, embedded solutions

• Active DoD Secret clearance with ability to secure special access

Desired Skills:

• Knowledge of security concerns with real-time operating systems.

• Knowledge of security standards, methods, and policies; risk and threat analysis; technical security safeguard; and operational security measures.

• Experience with all aspects of system design and development process

• Knowledge of Raytheon’s customer needs and organization

• DoD Top Secret clearance preferred

Required Education:

• Bachelor’s of Science (B.S.) in Science, Math, Engineering or related technical field

2012-10-22
06:15 [Event][New]

Submission: 9 November 2009
From February 7 to February 10
Location: Seoul, South Korea

2012-10-20
19:12 [Job][New]

The CS department at the University of Helsinki is building up a new secure systems research group in our NODES research unit. The initial focus of the group will be on mobile security. We want to explore security and privacy problems of mobile users and develop solutions that are simultaneously secure, easy-to-use and cost-effective to deploy. In particular, we are interested in figuring out how to use the wealth of contextual and historical information on mobile devices can be used in novel ways to solve these problems. Prof. N. Asokan, who recently joined the department after a long career in industrial research laboratories at IBM and Nokia will be leading the group.

We are looking for a post-doctoral researcher who will play an active role in building up the research program of the group. The successful candidate will have the unique opportunity of helping to shape the direction of a new research group as it is being set up. The researcher will be identifying potential research topics, helping to organize research seminars on those topics, carrying out research, and advising student research.

The ideal candidate will have the following attributes: You have recently completed (or are about to complete) a doctorate on a system security topic (e.g., platform security, network and protocol security) preferably focusing on mobility and mobile devices and users. You have a strong publication record. You also have research experience in one or more of the following areas: cloud computing, usability evaluations, user interaction design or data analytics. You enjoy and take pride in prototyping your research ideas and experimenting with them. You can communicate fluently in written and spoken English.

2012-10-18
00:17 [Pub][JoC]

Abstract  In this note, we show the existence of constant-round computational zero-knowledge proofs of knowledge for all . The existence of constant-round zero-knowledge proofs was proven by Goldreich and Kahan (Journal of Cryptology, 1996), and the existence of constant-round zero-knowledge arguments of knowledge was proven by Feige and Shamir (CRYPTO, 1989). However, the existence of constant-round zero-knowledge proofs of knowledge for all is folklore, to the best of our knowledge, since no proof of this fact has been published.

• Content Type Journal Article
• Pages 1-17
• DOI 10.1007/s00145-012-9132-7
• Authors

• Yehuda Lindell, Department of Computer Science, Bar-Ilan University, Ramat Gan, Israel

• Journal Journal of Cryptology
• Online ISSN 1432-1378
• Print ISSN 0933-2790

From: Mon, 15 Oct 2012 16:40:04 GMT

2012-10-16
18:17 [Pub][ePrint]

In this paper,we give an example of how symbolic computation are used to analyze the block cipher

PRESENT,an ultra-lightweight block cipher proposed by Bogdanov et al. at CHES\'07.The

block size is 64 bits and the key size can be 80 bit or 128 bit.Using Mathematica 7.0,this paper

obtains the unexpanded polynomial expressions of the output of round 1-6 of PRESENT-80(80-

bit key variant).The time complexity of getting these expressions is 4 minutes on a PC with a

2.6GHz CPU and 8G RAM.Then we expand the expressions of the output of round 1-2 and the

LSB(least significant bit) of the output of round 3 and obtain the ANFs(Algebraic Normal Form)

of these 129(=2*64+1) expressions. The time complexity of getting these ANFs is 22 minutes.It

it known that the time complexity of the classical method of computing the ANF of an n-ary

Boolean function from its truth table is O(n*2^n),with total time complexity of obtaining these 129

ANFs O(129*144*2^144) = O(2^158)(each of the 129 ANFs can be viewed as a 144-ary Boolean

function,where 144=64+80,the sum of the block size and the key size).As an application,we give

a side channel attack on PRESENT-80 under the single bit leakage model proposed by Dinur and

Shamir.If the LSB bit of the output of the 3rd round can be obtained without error,then with 200

known plaintexts,we can set up an equation system in terms of the master key bits and can recover

43 bits key by the Gr¨obner Basis method.Compared with the previous side channel attack

on PRESENT,such as Yang et al. in CANS 2009,Abdul-Latip et al. in ASIACCS 2011 and Zhao

et al. in 2011,each of which needs at least 2^13 chosen plaintexts,the data complexity of our attack

is the best.

15:17 [Pub][ePrint]

Information security has emerged as an important system and application metric. Classical security solutions use algorithmic mechanisms that address a small subset of emerging security requirements, often at high energy and performance overhead. Further, emerging side channel and physical attacks can compromise classical

security solutions. Hardware based security solutions overcome many of the limitations of classical security while consuming less energy and improving performance. Nanoelectronics based hardware security preserves all of these advantages while enabling conceptually new security mechanisms and security applications. This paper highlights

nanoelectronics based security capabilities and challenges. The paper describes nanoelectronics based hardware security primitives for device identification, digital forensics, and tamper detection. These primitives can be developed using the unique characteristics of emerging nanoelectronic devices such as complex device and system models, bidirectional operation, and temporal drift of the state variable. We conclude by identifying important desiderata and outstanding challenges in nanoelectronics based security.

15:17 [Pub][ePrint]

Concurrent signatures provide a way to exchange digital signature among parties in an efficient and fair manner. To the best of our knowledge, all the existing solutions are all proven secure in the random oracle model, which is only heuristic. How to build an efficient concurrent signature scheme in the standard model has been remaining an open problem since the introduction in EUROCRYPT 2004. In this paper we answer the problem affirmatively and propose a novel construction of concurrent signature, the security of which does not rely on the random oracle assumption. The ambiguity of our scheme is slightly different from the existing schemes, requiring that any one can produce indistinguishable ambiguous signatures using merely public information. Security of the new scheme is based on Computational Diffie-Hellman (CDH) assumption in the standard model, which is a rather standard and well-studied assumption in cryptography.

15:17 [Pub][ePrint]

We propose a simple, general, and unified framework for constructing unique ring signatures that simplify and capture the spirit of linkable ring signatures. The framework, which can be efficiently instantiated in the random oracle and the standard model, is obtained by generalizing the Bellare-Goldwasser PRF made public\" paradigm. Security of the first instantiation can be tightly related to the DDH problem. The scheme leads to the most efficient linkable/unique ring signature in the random oracle model, for a given level of provable security. The second one based on stronger assumptions partly simplifies and slightly improves sublinear size traceable ring signature of Fujisaki. Both of the improvements would be difficult without the general framework in hand.

15:17 [Pub][ePrint]

Present key sizes for symmetric cryptography are usually required to be at least 80-bit long for short-term protection, and 128-bit long for long-term protection. However, current tools for security evaluations against side-channel attacks do not provide a precise estimation of the remaining key strength after some leakage has been observed, e.g. in terms of number of candidates to test. This leads to an uncomfortable situation, where the security of an implementation can be anywhere between enumerable values (i.e. $2^{40}$ -- $2^{50}$ key candidates to test) and the full key size (i.e. $2^{80}$ -- $2^{128}$ key candidates to test). In this paper, we mitigate this important issue, and describe a key rank estimation algorithm that provides tight bounds for the security level of leaking cryptographic devices. As a result and for the first time, we are able to analyze the full complexity of \"standard\" (i.e. divide-and-conquer) side-channel attacks, in terms of their tradeoff between time, data and memory complexity.