Western European Workshop on Research in Cryptology

University of Bochum

WEWoRC 2007

July 4-6, 2007

Ruhr-University Bochum, Germany

Call for Papers (2.8 MB)   Slides (1.7 MB)

Mirrors: HGI Bochum WEWoRC.org
WEWoRC is a research meeting in the field of cryptology with a specific focus on young researchers. Topics of interest include, but are not limited to, the following
  • Foundations of cryptology (e.g., from computational number theory, complexity theory, combinatorics)
  • Secret-key cryptosystems and hash functions
  • Public-key cryptosystems
  • Modes of operation (e.g., Authenticated encryption and signcryption)
  • Cryptographic protocols (e.g., privacy, mobile security, distributed cryptography)
  • Implementation of cryptosystems and their integration into secure systems
  • Secure operating systems and trusted computing
  • Applications such as watermarking and code obfuscation
Important Dates:
  • Submission of abstract: Sun, June 3, 2007
  • Notification for talk: Mon, June 11, 2007
  • Early-bird registration: Wed, June 13, 2007
  • Workshop: Wed-Fri, July 4-6, 2007
  • Submission article (by invitation only): Mon, Oct 1, 2007
  • Notification for article: Wed, November 14, 2007
  • Submission final version: Mon, December 3, 2007


There are two types of submissions:
  • Short submissions (1-2 pages): they lead to a short talk (10-20 minutes)
  • Long submissions (3-5 pages): they lead to a long talk (30-45 minutes)
All submissions must be made in LaTeX and compile under pdflatex. Please read the following style-guide before submitting. Moreover, we provide a template and strongly encourage its use for all WEWoRC submissions. You can download the template in two formats:
  • ZIP: use unzip template.zip to unpack the template and all supporting files
  • .tar.gz: use tar -xzf template.tar.gz to unpack the template and all supporting files
The most important files of these two archives are the You can find all these files plus the graphic files in the above archives.

Submission is closed by now.

As WEWoRC targets specifically young researchers, invitation to submit an article for the proceedings will be given in particular to Ph.D. and M.Sc. students. Submission to the conference records (as outlined above) is free to everybody and we would welcome a wide varity of submissions here.


Registration fees are stated below. Here, "member" means a member of the German computer science association, an Ecrypt institution, or an EIDMA institution.

Normal registration fee (member):

  • Student: 140 euro (120 euro)
  • University and Government agency: 220 Euro (190 euro)
  • Other (e.g., companies): 340 euro (300 euro)
Early bird (member): until Wed, June 13, 2007
  • Budget [1]: 55 euro (50 euro)
  • Student: 115 euro (95 euro)
  • University and Government agency: 160 Euro (145 euro)
  • Other (e.g., companies): 270 euro (245 euro)

Note that the registration fees above are by payment via bank transfer. Keep in mind that euro payments within the European Union can be done for the same fees as within your own country. We also offer payment via credit card. However, in this case the fees increase by 5.5% to cover the additional external handling costs we have.

You can register using the following link.

[1] budget includes conference records but not the proceedings. Moreover, it does not include the conference dinner or other meals. It is only available for students.

Travel / Venue

Here you find travel information for reaching Bochum and its university. For arriving in Bochum by plane, the city tourist information provides a good starting point.

Registration on July 3 is in Room IC 4 / 146, the reception on July 3 in Room IC 4 / 39-41. IC is the building, 4 indicates the floor, 39, 41, and 146 are the room numbers. See the map of the university to find the IC building (upper right part, blue building).

From July 4 - 6 we will move venue and be in the "Veranstaltungszentrum" (event centre) close to the student restaurant (Mensa - marked CASPO on the university map, see bottom of the orange building in the bottom-centre). Both the later registration and the talks will take place in the event centre.


We are honoured to have George Danezis (Katholieke Universiteit Leuven, Belgium) and David Naccache (ENS Paris, France) as invited speakers during WEWoRC 2007.

You can download the accepted papers (2.9 MB) here.

Tuesday, July 3rd, 2007:


17:00 – 19:00

Welcome Reception (IC 4 / 39 + 41)

Registration (IC 4 / 146)





Wednesday, July 4th, 2007:


8:30 – 9:00

         Registration (Information Desk – near Room 1)


8:50 – 9:00 Welcome (Room 1) – Ahmad Sadeghi


9:00 – 10:40 Session 1 (Room 1) – Roberto Avanzi


A Privacy Protection Scheme for a Scalable Control Method in

Context-Dependent Services

Rei Yoshida, Rie Shigetomi, Kazuki Yoshizoe, Akira Otsuka, and Hideki Imai


The GPS identification Scheme Using Frobenius Expansions

Waldyr Benits and Steven Galbraith


Efficient Assembly Implementation of Dragon, LEX, Salsa20 and

Sosemanuk on 8-bit AVR Microcontrollers

Gordon Meiser, Thomas Eisenbarth, Kerstin Lemke-Rust, Christof Paar


MPSoC-Coupled Hardware Accelerator for

Elliptic Curve Cryptography in Network Application Domain

Christoph Puttmann and Jamshid Shokrollahi



10:40 – 11:10 Coffee Break



11:10 – 12:25 Session 2 (Room 1) – Ralph Wernsdorf


Finding Message Pairs Conforming to Simple SHA-256 Characteristics:

Work in Progress

Marko Hölbl, Christian Rechberger, Tatjana Welzer


XOR-Hash : A Hash Function Based on XOR

Stéphane Manuel and Nicolas Sendrier


Efficient Hash Collision Search Strategies on Special-Purpose Hardware

Tim Güneysu, Christof Paar, Sven Schäge



12:25 – 14:30 Lunch Break



14:30 – 15:30 Invited Talk (Room 1) – Stefan Lucks


Cryptography in Anonymous Communications

George Danezis


15:30 – 16:20 Session 3 (Room 1)


Group Signatures with Observers Revisited

Thomas Schwarzpaul


Modified HB Authentication Protocol

Selwyn Piramuthu, Yu-Ju Tu



16:20 – 16:50 Coffee Break



16:50 – 18:40 Session 4 (Room 1) – Alexander May


Cryptography Based on Quadratic Forms: Complexity Considerations

Rupert J. Hartung


Lattice-Based Computationally-Efficient Private Information Retrieval


Carlos Aguilar-Melchor and Philippe Gaborit


A McEliece-like Symmetric-Key Cryptosystem Based on Quasi-Cyclic

Low-Density Parity-Check Codes1

Ali Akbar Sobhi Afshar, Taraneh Eghlidos, Mohammad Reza Aref


A Three Based Chaotic Maps Block Cipher

Mabrouka Hagui, Hedi Khammari and Bechir Ayeb






Thursday, July, 5th, 2007



9:00 – 9:30 Session 5A (Room 1) – Jörg Schwenk


Toward a Concrete Security Proof of Courtois, Finiasz and Sendrier Signature Scheme

Léonard Dallot


HFE - solved or saved?

Jintai Ding, Dieter Schmidt and Fabian Werner



9:00 – 9:30 Session 5B (Room 3) – Ulrich Kühn


AES Cache-Timing Attacks Verified

Joris Plessers, Ingrid Verbauwhede


A Lightweight Hardware Implementation of the Stream Cipher VEST-4

Timo Gendrullis, Timo Kasper, and Christof Paar



9:30 – 9:35 Synchronisation Break



9:35 – 10:05 Session 6A (Room 1) – Jörg Schwenk


Cryptanalysis of the MOR System (extended abstract)

 Anja Korsten


On the Permutations of KHAZAD

Ralph Wernsdorf



9:35 – 10:05 Session 6B (Room 3) – Bodo Möller


Exploring Trade-offs Between Area, Performance and Security

in HW/SW Co-design of ECC

Caroline Vanderheyden, Junfeng Fan, Kazuo Sakiyama, and Ingrid Verbauwhede


Low-Weight Joint Window Nonadjacent Form

Wei-Hua He and Fei-Ming Juan



10:05 – 10:10 Synchronisation Break



10:10 – 10:40 Session 7A (Room 1) – Ulrich Kühn


BDD-based Cryptanalysis of Hardware-oriented Stream Ciphers

Dirk Stegemann


Preimages for Reduced-Round Tiger

Sebastiaan Indesteege and Bart Preneel



10:10 – 10:40 Session 7B (Room 3) – Bodo Möller


Algebraic Attacks on Block Ciphers with Several Plaintext-Ciphertext Pairs

Nicolas T.Courtois and Blandine Debraize


Lattice-based partial key exposure attacks on signature schemes

Paul Kubwalo


10:40 – 11:10 Coffee Break



11:10 – 12:00 Session 8 (Room 1) - Jamshid Shokrollahi


Template Attacks On Masking: An Interpretation

Benedikt Gierlichs and Kare Janussen


Wibree Security — Towards Better Energy Efficiency

Jan-Erik Ekberg



12:00 – 13:45 Lunch Break



13:45 – 22:45 Social Programme (including bus transfer)


  • Visit of the world heritage site Zeche Zollverein (from 15:00)
  • Conference Dinner in the Casino Zollverein (from 19:00)

Friday, July 6th, 2007


9:00 – 10:40 Session 9 (Room 1) – Frederik Armknecht


A new Security Model and a Generic Construction for CCA2-Secure Certificateless Cryptosystems

Ewan Fleischmann


Encryption Based Trust Negotiation

Dalia Khader


A Threshold Scheme with Disenrollment (extended abstract)

Michael Beiter


A New Threshold Audio Secret Sharing Scheme

Mohammad Ehdaie, Taraneh Eghlidos, Mohammad Reza Aref


10:40 – 11.10 Coffee Break


11:10 – 12:25 Session 10 (Room 1) – Mark Manulis


Attacks on the Stream Ciphers TPy6 and Py6 and Design of New Ciphers TPy6-A and TPy6-B

Gautham Sekar, Souradyuti Paul and Bart Preneel


The Impact of Entropy Loss Caused by Random Functions

Andrea Röck


Cryptanalysis of Achterbahn-128/80 with a new Keystream Limitation

Mara Naya-Plasencia



12:25 – 14:30 Lunch Break


14:30 – 15:30 Invited Talk (Room 1) – Christopher Wolf


Products of small primes in cryptography and error-correction

David Naccache


15:30 – 16:20 Session 11 (Room 1) – Ahmad Sadeghi


Using Two-Steps Hash Function to Support Trustworthy Signing in XML


Sebastian Gajek, Lijun Liao and Jörg Schwenk


Browser-based Authentication Protocols for Naive Users

Sebastian Gajek, Mark Manulis, Ahmad-Reza Sadeghi and Jörg Schwenk



16:20 Final Coffee Break


WEWoRC 2007 is co-chaired by Stefan Lucks (Bauhaus-University Weimar, Germany), Ahmad-Reza Sadeghi (Ruhr-University Bochum, Germany), and Christopher Wolf (Ruhr-University Bochum, Germany). It is organised by the German Special Interest Group on Cryptology (FG Krypto) and the Horst-Görtz-Institute on Computer Security Bochum.


Academic Partners
We thank our sponsors for their support.
Silver Sponsors


Bronze Sponsors

Programme Committee

  • Ammar Alkassar (Sirix AG, Germany)
  • Frederik Armknecht (NEC, Germany)
  • N. Asokan (Nokia Research Helsinki, Finland)
  • Roberto Avanzi (RU Bochum, Germany)
  • Lynn Batten (Deakin University, Australia)
  • Alex Biryukov (University of Luxembourg, Luxembourg)
  • Johannes Blömer (Paderborn, Germany)
  • Colin Boyd (Queensland University of Technology, Australia)
  • Lejla Batina (KU Leuven, Belgium)
  • Dario Catalano (CNRS-ENS, France; Universitá di Catania, Italy)
  • Christophe Clavier (Gemalto, France)
  • Jean-Sébastien Coron (University of Luxembourg, Luxembourg)
  • Steven Galbraith (Royal Holloway, University of London, UK)
  • Joachim von zur Gathen (b-it Bonn, Germany)
  • Willi Geiselmann (TU Karlsruhe, Germany)
  • Marc Girault (France Telecom, France)
  • Louis Goubin (University of Versailles, France)
  • Aline Gouget (Gemalto, France)
  • Helena Handschuh (Spansion, France)
  • Florian Hess (TU Berlin, Germany)
  • Erwin Hess (Siemens, Germany)
  • Ellen Jochemsz (TU Eindhoven, The Netherlands)
  • Dogan Kesdogan (RWTH Aachen, Germany)
  • Eike Kiltz (CWI, The Netherlands)
  • Ulrich Kühn (sirrix, Germany)
  • Arjen Lenstra (EPFL, Swiss)
  • Francoise Levy-dit-Vehel (ENSTA, France)
  • Gregor Leander (RU Bochum, Germany)
  • Stefan Lucks (University of Mannheim, Germany)
  • Keith Martin (Royal Holloway, University of London, UK)
  • Alexander May (TU Darmstadt, Germany)
  • Chris Mitchell (Royal Holloway, University of London, UK)
  • David Naccache (ENS Paris, France)
  • Heike Neumann, (Philips Semiconductors, Germany)
  • Svetla Nikova (KU Leuven, Belgium)
  • Siddika Berna Ors (Istanbul Technical University, Turkey)
  • Elisabeth Oswald (Bristol, UK)
  • Christof Paar (RU Bochum, Germany)
  • Kenny Paterson (Royal Holloway, University London, UK)
  • Bart Preneel (KU Leuven, Belgium)
  • Vincent Rijmen (TU Graz, Austria; Cryptomathic, Denmark)
  • Ahmad-Reza Sadeghi (RU Bochum, Germany)
  • Christian Tobias (Utimaco, Germany)
  • Rei Safavi-Naini (University of Wollongong, Australia)
  • Jörg Schwenk (RU Bochum, Germany)
  • Nicolas Sendrier (INRIA, France)
  • Stefaan Seys (KU Leuven, Belgium)
  • Heiko Stamer (Kassel, Germany)
  • Henk van Tilborg (TU Eindhoven, The Netherlands)
  • Pim Tuyls (Philips, The Netherlands)
  • Pascal Véron (University of Toulon, France)
  • Moti Yung (Columbia University and RSA Laboratories, USA)
  • Michael Welschenbach (SRC Security Research&Consulting, Germany)
  • Ralf-P. Weinmann (TU Darmstadt, Germany)
  • Thomas Wilke (Kiel, Germany)
  • Ralph Wernsdorf (Rohde & Schwarz SIT GmbH, Germany)
  • Christopher Wolf (PwC Luxembourg; K.U.Leuven, Belgium)
  • Po-Wah Yau (Royal Holloway, University of London, UK)
  • Erik Zenner (Cryptico, Denmark)


We have compiled this list of hotels to the best of our knowledge. However, prices may change without us being informed. Hence: please check yourself with the hotel before making a definite booking. Please contact us in case you notice any discrepancies.
Hotels in the City Center of Bochum:
Hotel rooms with a demand contingent; please quote contingent code "WEWoRC 2007" in your booking.

Kolpinghaus Gaststätte GmbH Bochum
3-bed rooms for 23.00 euro with bathroom on the floor p.pers./night incl. breakfast
2-bed rooms for 23.00 euro with bathroom on the floor p.pers./night incl. breakfast
single rooms with bathroom on the floor for 28.00 euro /night incl. breakfast
2-bed rooms for 32.00 euro p.pers /night incl. breakfast
single rooms for 44.00 euro /night incl. breakfast
Maximilian-Kolbe-Str. 14-18
DE-44793 Bochum
Phone: (+49)234/60190
Fax: (+49)234/65852
hotel-kolpinghaus-bochum (at) arcor.de

Hotel Ibis Am Hauptbahnhof
single 55.76 euro, double 65.26 euro incl. breakfast
Kurt- Schumacher- Platz 13-15
DE-44787 Bochum
Phone: (+49)234/91430
Fax: (+49)234/680778

Hotel Ibis Bochum Zentrum
single 55.76 euro, double 65.26 euro incl. breakfast
Universitätsstrasse 3
DE-44789 Bochum
Phone: (+49)234/33311
Fax: (+49)234/3331867

Other hotels in the city of Bochum:
Park Inn Bochum
single 89 euro, double 102.50 - incl. breakfast
Massenbergstr. 19-21
DE-44787 Bochum
Phone: (+49)234/969-1221
Fax: (+49)234/969-2222
bochum (at) eventhotels.com

Acora Hotel und Wohnen
single 71 euro, double 89 euro - incl. breakfast
Nordring 44-50
DE-44787 Bochum
Phone: (+49)234/6896-985
Fax: (+49)234/6896-700

Hotel Renaissance
single 93 euro, double 93 euro without breakfast
Stadionring 20
DE-44791 Bochum
Phone: (+49)234/6101-0
Fax: (+49)234/6101-111

Hotel Courtyard by Mariott
single 107 euro, double 121 euro incl. breakfast
Stadtpark (City Park)
Klinikstr. 43-45
DE-44791 Bochum
Phone: (+49)234/6100-0
Fax: (+49)234/6100-444

Hotel near to the Ruhr-University:
Wald- und Golfhotel GmbH
single 70 euro, double 100 euro incl. breakfast
Im Lottental
Grimbergstrasse 52a
44797 Bochum  
Tel. (+49)234/97 96 0
Fax  (+49)234/97 96 293
buchung (at) wald-und-golfhotel.de

Sights and Places of Interest

Here are some tips and ideas how you could spend your free time: Enjoy it!
Ruhr Region

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