International Association for Cryptologic Research

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2012-10-07
21:17 [Pub][ePrint] Leakage Squeezing of Order Two, by Claude Carlet and Jean-Luc Danger and Sylvain Guilley and Houssem Maghrebi

  In masking schemes, \\emph{leakage squeezing} is the study of the optimal shares\' representation, that maximizes the resistance order against high-order side-channel attacks.

Squeezing the leakage of first-order Boolean masking has been problematized and solved previously in~\\cite{DBLP:conf/africacrypt/MaghrebiCGD12}.

The solution consists in finding a bijection $F$ that modifies the mask, in such a way that its graph, seen as a code, be of greatest dual distance.

This paper studies second-order leakage squeezing, \\emph{i.e.} leakage squeezing with two independent random masks.

It is proved that, compared to first-order leakage squeezing, second-order leakage squeezing at least increments (by one unit) the resistance against high-order attacks, such as high-order correlation power analyses (HO-CPA).

Now, better improvements over first-order leakage squeezing are possible by relevant constructions of the squeezing bijections pair.

We provide with linear bijections that improve by strictly more than one (instead of one) the resistance order.

Specifically,

when the masking is applied on bytes (which suits AES),

resistance against $1$st-order (resp. $2$nd-order) attacks is possible with one (resp. two) masks.

Optimal leakage squeezing with one mask resists HO-CPA of orders up to $5$.

In this paper, with two masks, we provide resistance against HO-CPA not only of order $5+1=6$, but also of order $7$.



21:17 [Pub][ePrint] On Transaction Pseudonyms with Implicit Attributes, by Stefan G. Weber

  Transaction pseudonyms with implicit attributes are a novel approach to multilevel linkable transaction pseudonyms. We extend earlier work of Juels and Pappu on reencryption-based transaction pseudonyms, by developing new mechanisms for controlled pseudonym linkability.

This includes mechanisms for cooperative, stepwise re-identication

as well as individual authentication of pseudonyms. Our proposal makes

use of efficient techniques from the area of secure multiparty computation and cryptographically secure PRNGs.



21:17 [Pub][ePrint] Improved Zero-knowledge Proofs of Knowledge for the ISIS Problem, and Applications, by San Ling and Khoa Nguyen and Damien Stehle and Huaxiong Wang

  In all of existing efficient proofs of knowledge of a solution to the Inhomogeneous Small Integer Solution ISIS problem, the knowledge extractor can only output a vector that is about $\\sqrt{n}$ times longer than the witness possessed by the prover. As a consequence, in many cryptographic schemes that use these proof systems as building blocks, there exists a gap between the hardness of solving the underlying ISIS problem and the hardness used in the security reductions. In this paper, we generalize Stern\'s protocol to obtain two statistical zero-knowledge proofs of knowledge for the ISIS problem (in the $l_\\infty$ norm) that remove this gap. Our result yields the potential of relying on weaker security assumptions for various lattice-based cryptographic constructions. As applications of our proof system, we introduce a concurrently secure identity-based identification scheme based on the worst-case hardness of the $\\mathrm{SIVP}_{\\widetilde{O}(n^{1.5})}$ problem (in the $l_2$ norm) in general lattices in the random oracle model, and an efficient statistical zero-knowledge proof of plaintext knowledge with small constant gap factor for Regev\'s encryption scheme.





2012-10-04
20:25 [Event][New] HOST: IEEE International Symposium on HARDWARE-ORIENTED SECURITY and TRUST

  Submission: 10 December 2012
Notification: 22 February 2013
From June 2 to June 3
Location: Austin, United States
More Information: http://www.hostsymposium.org/




2012-10-03
17:11 [News] SHA-3 Winner: Keccak

  NIST has announce Keccak as SHA-3 winner. You find more information about Keccak at http://keccak.noekeon.org/ The full statement of the NIST is found at the link below.

14:53 [Event][New] LightSec 2013: International Workshop on Lightweight Cryptography for Security & Privacy

  Submission: 25 January 2013
Notification: 8 March 2013
From May 6 to May 7
Location: Gebze, Turkey
More Information: http://www.light-sec.org




2012-10-02
15:17 [Pub][ePrint] An Attack on a Fully Homomorphic Encryption Scheme, by Hu Yupu, Wang Fenghe

  In this paper we present an attack on a fully homomorphic encryption scheme on PKC2010.

We construct a modi¯ed secret key, a modi¯ed decryption algorithm and a subset of the ciphertext

space. When the ciphertext is from the subset, we can correctly decrypt it by our modi¯ed secret key

and modi¯ed decryption algorithm. We also discuss when our modi¯ed decryption algorithm is e±cient,

and when the subset is not negligible.



15:17 [Pub][ePrint] Aggregating CL-Signatures Revisited: Extended Functionality and Better Efficiency, by Kwangsu Lee and Dong Hoon Lee and Moti Yung

  Aggregate signature is public-key signature that allows anyone to aggregate different signatures generated by different signers on different messages into a short aggregate signature. Although aggregate signatures have many applications like secure routing protocols and software module authentications, it is not easy to devise a suitable aggregate signature scheme that satisfies the conditions of real applications such that the size of public keys should be short, the size of aggregate signatures should be short, and the aggregate signing and aggregate verification should be efficient.

In this paper, we propose two aggregate signature schemes based on the Camenisch-Lysyanskaya signature scheme that sufficiently satisfy the conditions of real applications. At first, we construct an efficient sequential aggregate signature scheme and prove its security under the LRSW assumption without random oracles. The proposed scheme has the shortest size of public keys among the sequential aggregate signature schemes and very short size of aggregate signatures. Additionally, the aggregate verification of this scheme is very efficient since it only requires constant number of pairing operations and $l$ number of exponentiations where $l$ is the number of signers in an aggregate signature. Next, we construct an efficient synchronized aggregate signature scheme and prove its security under the LRSW assumption in the random oracle model. The proposed scheme has very short size of public keys and the shortest size of aggregate signatures among the synchronized aggregate signature schemes. The signing and aggregate verification is also very efficient since these requires constant number of pairing operations and $l$ number of exponentiations.

Furthermore, a signer of our aggregate signature schemes can use two mode of aggregation ``sequential\'\' and ``synchronized\'\' at the same time just using the same private key and the public key since the private keys and the public keys of two schemes are the same.



14:26 [Job][New] Postdoc, EPFL, Lausanne, Switzerland

  The Laboratory for Security and Cryptography (LASEC) at EPFL is hiring a post doctoral researcher. Applicants are encouraged to apply to job_lasec (at) epfl.ch by sending a detailed CV and a research plan.

LASEC is active in research on cryptography and security. More specifically, our main interests span (but are not limited to) the following:

  • Cryptographic analysis

  • Design of cryptographic algorithms and protocols

  • Lightweight cryptography

  • Secure communication

  • Wireless security

  • Composability and setup assumptions

  • Methodology and theory for cryptography

  • Number theory and cryptography.

The selection of applicants will be made on a competitive basis.

Besides conducting top-quality research, postdocs are required to participate the the lab activities such as training students at all levels, running projects, fund raising, etc.

EPFL is a top-ranked research and teaching institution that attracts some of the best intellects in the world. EPFL offers excellent facilities, environment, and salaries. The EPFL campus is a multi cultural, idyllic spot overlooking Lake Geneva and facing the Alps.

14:26 [Job][New] PhD student, EPFL, Lausanne, Switzerland

  The Laboratory for Security and Cryptography (LASEC) and the Laboratory for Cryptologic Algorithms (LACAL) at EPFL are hiring PhD students for Fall 2013. Applicants are encouraged to apply to the EDIC doctoral school (the application deadline is January 15, 2013) and, in parallel, to notify us at job_lasec (at) epfl.ch.

LASEC and LACAL are active in research on cryptography and security. More specifically, our main interests span (but are not limited to) the following:

  • Efficient cryptologic calculations

  • Cryptographic analysis

  • Design of cryptographic algorithms and protocols

  • Lightweight cryptography

  • Secure communication

  • Wireless security

  • Composability and setup assumptions

  • Methodology and theory for cryptography

  • Number theory and cryptography.

The selection of applicants will be made on a competitive basis.

EPFL is a top-ranked research and teaching institution that attracts some of the best intellects in the world. EPFL offers excellent facilities, environment, and salaries. The EPFL campus is a multi cultural, idyllic spot overlooking Lake Geneva and facing the Alps.

09:05 [Event][New] ECRYPT II AES Day

  From October 18 to October 18
Location: Bruges, Belgium
More Information: https://www.cosic.esat.kuleuven.be/ecrypt/AESday/