International Association for Cryptologic Research

# IACR News Central

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2013-02-27
06:56 [Event][New]

From September 16 to September 18
Location: Leuven, Belgium

2013-02-25
16:56 [Event][New]

Submission: 15 March 2013
Notification: 4 April 2013
From June 27 to July 2
Location: Santa Clara, CA, USA

16:55 [Event][New]

Submission: 8 July 2013
Notification: 16 August 2013
From October 14 to October 14
Location: Atlanta, GA, United States

2013-02-23
18:32 [Job][New]

The cryptography group at Aalto University School of Science is specialized in statistical cryptanalysis of symmetric-key cryptographic primitives as well as implementation efficiency and security of both asymmetric-key and symmetric-key primitives. Also mathematical structures that provide resistance against such attacks belong to the group´s interest areas. In the current call we look for researchers who have PhD degree and background in the areas mentioned above.

2013-02-22
18:00 [Event][New]

Submission: 30 June 2013
Notification: 10 August 2013
From November 26 to November 28
Location: Aksaray, Turkey

2013-02-21
20:47 [Event][New]

From March 27 to March 27
Location: Brussels, Belgium

20:46 [Event][New]

Submission: 2 April 2013
Notification: 28 May 2013
From July 9 to July 11
Location: Graz, Austria

13:17 [Pub][ePrint]

In this paper, we describe a new algorithm for discrete logarithms in

small characteristic. It works especially well when the characteristic

is fixed. Indeed, in this case, we obtain a total complexity of $L(1/4+o(1)).$

2013-02-20
19:17 [Pub][ePrint]

We initiate the study of quantum-secure digital signatures and quantum chosen ciphertext security. In the case of signatures, we enhance the standard chosen message query model by allowing the adversary to issue quantum chosen message queries: given a superposition of messages, the adversary receives a superposition of signatures on those messages. Similarly, for encryption, we allow the adversary to issue quantum chosen ciphertext queries: given a superposition of ciphertexts, the adversary receives a superposition of their decryptions. These adversaries model a natural post-quantum environment where end-users sign messages and decrypt ciphertexts on a personal quantum computer.

We construct classical systems that remain secure when exposed to such quantum queries. For signatures we construct two compilers that convert classically secure signatures into signatures secure in the quantum setting and apply these compilers to existing post-quantum signatures. We also show that standard constructions such as Lamport one-time signatures and Merkle signatures remain secure under quantum chosen message attacks, thus giving signatures whose quantum security is based on generic assumptions. For encryption, we define security under quantum chosen ciphertext attacks and present both public-key and symmetric-key constructions.

19:17 [Pub][ePrint]

We present a deterministic algorithm to find nonlinear S-box approximations, and a new nonlinear cryptanalytic technique; the \"filtered\" nonlinear attack, which achieves the lowest data complexity of any known-plaintext attack on reduced-round Serpent so far. We demonstrate that the Wrong-Key Randomization Hypothesis is not entirely valid for attacks on reduced-round Serpent which rely on linear cryptanalysis or a variant thereof, and survey the effects of this on existing attacks (including existing nonlinear attacks) on 11 and 12-round Serpent.

19:17 [Pub][ePrint]

We provide a construction for functional encryption over the set of recursive languages.

In this scheme, a secret key $\\sk_{\\mathcal{M}}$ encodes a halting double-stack deterministic pushdown

automaton (2DPDA) $\\mathcal{M}$ that accepts by final state. Encryption algorithm takes a message $m$

and a string $w$ as input and outputs a ciphertext $\\cipher$. A user possessing $\\sk_{\\mathcal{M}}$ can

decrypt $\\cipher$ only if $\\mathcal{M}$ accepts $w$. Halting 2DPDAs can simulate halting deterministic

Turing machines and hence our construction essentially covers all

recursive languages.

The construction is built upon Waters\' bilinear pairing-based functional encryption scheme

over regular languages. The main technical novelty is in handling stack contents and

$\\lambda$-transitions (i.e., transitions that do not advance the input pointer)

of the automata. This is reflected both in the construction and the security arguments.

The scheme is shown to be selectively secure based on the decision $\\ell$-expanded bilinear

Diffie-Hellman exponent assumption introduced by Waters.