[crypto] [secdm at tue.nl: Program Crypto Working Group, May 22, 2015]

R. Hirschfeld ray at unipay.nl
Wed May 13 12:01:49 CEST 2015


------- Start of forwarded message -------
From: Secretariaat DM <secdm at tue.nl>
Subject: Program Crypto Working Group, May 22, 2015
Date: Wed, 13 May 2015 09:42:04 +0000

Dear all,

Herewith I send you the program of the CWG-meeting on Friday, May 22, 2015.

With kind regards / Met vriendelijke groeten,
Anita Klooster
secretary of the section Discrete Mathematics

[cid:image001.gif at 01CB8FB5.88A9C0F0]

Dept. of Mathematics and Computer Science
MF 4.058
Office hours: Monday and Friday 08.30-12.30 h / Tuesday and Wednesday 08.30-17.00 h
Telephone: +31 (0)40 2472254
Email: secdm at tue.nl<mailto:secdm at tue.nl>


CRYPTO WORKING GROUP


Friday, May 22, 2015

                                                De Kargadoor (http://www.kargadoor.nl/utrecht/zaalverhuur.html)
                                                Oudegracht 36, Utrecht



Program

10.45 - 11.30 hrs.   Peter van Emde Boas (ILLC / FNWI / UvA / Bronstee.com Software & Services B.V. Heemstede),
                                               The use of Information and Spycraft in Ancient Chinese Warfare

11.30 -  11.45 hrs.   Coffee / tea break

11.45 - 12.30 hrs.    Leo Ducas (CWI),

Recovering Short Generators of Principal Ideals in Cyclotomic Rings

(joint work with Ronald Cramer, Chris Peikert and Oded Regev)

12.30 -  14.00 hrs.   Lunch break (lunch not included)


14.00 - 14.45 hrs.    Moritz Neikes (GMX Germany),
                                   Fingerprint scheduling for dining-cryptographer networks


14.45 - 15.00 hrs.    Coffee / tea break


15.00 - 15.45 hrs.    Andreas Hülsing & Peter Schwabe (TU/e & RU Nijmegen),

                                   SPHINCS: practical stateless hash-based signatures




Abstract talk Peter van Emde Boas: The use of Information and Spycraft in Ancient Chinese Warfare

According to my edition of D. Kahn, the Codebreakers (first edition of 1967) Cryptography was hardly ever practised in Ancient China. He explains this as being related to the ideographic writing system used in China.

On the other hand the Chinese, during the first millennium BC developed an extensive literature on strategic theory, including topics like good governance, information gathering, spycraft and deception. The most famous author is Sun Tzu, whose text of the thirteen chapters "The Art of War" has become very popular during the last sixty years, particularly in the world of business. Sun Tzu stresses the importance of being prepared for war; if well prepared you may win the war without serious fighting.

In the talk we will look into the ideas about information use and spycraft in these ancient works. We will find some ideas related to Cryptography. Furthermore I will present some instances from Chinese history how information was used for strategic purposes.

Abstract talk Leo Ducas: Recovering Short Generators of Principal Ideals in Cyclotomic Rings (joint work with Ronald Cramer, Chris Peikert and Oded Regev)

A handful of recent cryptographic proposals rely on the conjectured hardness of the following problem in the ring of integers of a cyclotomic number field: given a basis of an ideal that is guaranteed to have a "rather short" generator, find such a generator. In the past year, Bernstein and Campbell-Groves-Shepherd have sketched potential attacks against this problem. Most notably, the latter authors claimed a quantum polynomial-time algorithm (alternatively, replacing the quantum component with an algorithm of Biasse and Fieker would yield a classical subexponential-time algorithm). A key claim of Campbell et al. is that one step of their algorithm-namely, decoding the log-unit lattice of the ring to recover a short generator from an arbitrary one-is efficient (whereas the standard approach takes exponential time). However, very few convincing details were provided to substantiate this claim, and as a result it has met with some skepticism.

In this work, we remedy the situation by giving a rigorous theoretical and practical confirmation that the log-unit lattice is indeed efficiently decodable, in cyclotomics of prime-power index. The proof consists of two main technical contributions: the first is a geometrical analysis, using tools from analytic number theory, of the canonical generators of the group of cyclotomic units. The second shows that for a wide class of typical distributions of the short generator, a standard lattice-decoding algorithm can recover it, given any generator.

Abstract talk Moritz Neikes: Fingerprint scheduling for dining-cryptographer networks

In many communication scenarios it is not sufficient to protect only the content of the communication, it is necessary to also protect the identity of communicating parties. The protocol that offers the strongest anonymity guarantees is the Dining Cryptographer (DC) protocol proposed by Chaum in 1988. Unfortunately the strong anonymity guarantees come at the price of limited performance and scalability and multiple issues that make deployment complicated in practice.

Fingerprint scheduling addresses one of the scalability issues, namely slot reservation. It is a new technique that allows participants to negotiate communication slots without losing anonymity. Fingerprint scheduling is at the same time simple, efficient and yields good results for both busy networks and networks that are mainly idle.

Abstract talk Andreas Hülsing & Peter Schwabe: SPHINCS: practical stateless hash-based signatures

All asymmetric cryptography that is widely deployed today can be broken in polynomial time by a large quantum computer, once such a computer exists. Post-quantum cryptography proposes alternatives that,   as far as we know, will not be efficiently broken by a large quantum computer. One of the best understood post-quantum cryptographic constructions are hash-based signatures. Their security relies solely   on certain standard properties of a cryptographic hash-function, they are reasonably efficient and both signatures and keys are short. The big problem is that they are stateful, i.e., the secret key needs to be updated after each signature. This poses various problems for practical deployment when considering backups, load balancing, or even typical APIs for signatures. In this talk we will present SPHINCS as the first efficient stateless hash-based signature scheme.
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