My research: publications, presentations, talks, reports, courses, slides, + echoes in the press/Internet.
-
Nicolas
T. Courtois, Sean O'Neil and Jean-Jacques Quisquater: Practical
Algebraic Attacks on the Hitag2 Stream Cipher, In 12th Information
Security Conference, ISC 2009, Pisa, Italy 7-9 September 2009, Springer
LNCS.
Also will be presented at eSmart, the european smart card security conference, September 22-25, Sophia Antipolis, French Riviera, with proceedings (slides presented) being published as a CD-ROM. -
Card-only
attacks on MiFare Crypto-1 cipher.
Nicolas T. Courtois: The Dark Side of Security by
Obscurity and Cloning MiFare Classic Rail and Building Passes Anywhere, Anytime
, new attack requires only 300 queries to the card and will appear in SECRYPT
2009 - International Conference on Security and Cryptography: 7-10 July 2009,
Milan, Italy. A version of this paper is available
here.
This paper concerns more than 1 billion of smart cards and compromises very heavily the security of thousands of buildings and several train/bus/parking payment systems in Europe and elsewhere (allowing for example unauthorized access to buildings, travel for free, free parking etc.). Other researchers also found other and different card-only attacks on MiFare Classic but they are more than 10 times more difficult to handle in terms of online time (more queries to the card, for example when standing or sitting next to the victim).
The best practical attack currently known on MiFare Classic is actually a combination of our attack with 300 queries to find the first key (estimated time: 10 seconds with Proxmark3), and the Nested Authentication attack from the Oakland paper to recover all the other keys (which is extremely fast). Nicolas
T. Courtois: Self-similarity Attacks on Block Ciphers
and Application to KeeLoq, In International Workshop on Coding and
Cryptography, May 10-15, 2009, Ullensvang, Norway.
Algebraic attacks on MiFare Crypto-1
cipher. At eprint.iacr.org/2008/166/
This work was a bit of disappointment: we could recover the key in 12 seconds
but this automated cryptanalysis, we did not realise how weak this cipher
actually was, and later Dutch researchers
have shown a simpler and better attack that does the job in less than
0.1 seconds (in contrast our attack is more generally applicable and can also
break Hitag2, to appear soon).
- Nicolas Courtois: Improved Brute Force Attacks on KeeLoq, In 6th ESCAR conference - Embedded Security in Cars 2008. Hotel Hafen Hamburg (Germany), 18-19 November 2008.
- Nicolas Courtois and Blandine Debraize: Algebraic Description and Simultaneous Linear Approximations of Addition Modulo 2^n, In ICICS 2008, 10th International Conference on Information and Communications Security, 20 - 22 October, 2008, Birmingham, UK. Will appear in LNCS, Springer.Also was presented at SASC 2008 workshop, Lausanne, Switzerland, 13-14 February 2008.
- Press report Zlamany szyfr karty Oyster, on the Internet service of Gazeta Wyborcza, one of the biggest Polish daily newspapers.
- Côme Berbain, Olivier Billet, Anne Canteaut, Nicolas Courtois, Henri Gilbert, Louis Goubin, Aline Gouget, Louis Granboulan, Cédric Lauradoux, Marine Minier, Thomas Pornin and Hervé Sibert: Sosemanuk , a Fast Software-Oriented Stream Cipher, In New Stream Cipher Designs, The eSTREAM Finalists, LNCS 4986, pp. 98-118, Springer, 2008.
- Côme Berbain, Olivier Billet, Anne Canteaut, Nicolas Courtois, Blandine Debraize, Henri Gilbert, Louis Goubin, Aline Gouget, Louis Granboulan, Cédric Lauradoux, Marine Minier, Thomas Pornin and Hervé Sibert: Decim v2, In New Stream Cipher Designs, The eSTREAM Finalists, LNCS 4986, pp. 140-151, Springer, 2008.
Nicolas Courtois, Gregory V. Bard
and Andrey Bogdanov: Periodic Ciphers with
Small Blocks and Cryptanalysis of KeeLoq , In Tatra
Mountains Mathematic Publications, post-proceedings of Tatracrypt 2007
conference, 2009.
- Sean O'Neil, Nicolas Courtois: Reverse-engineered Philips/NXP Hitag2 Cipher, presented at the rump session of FSE 2008, Lausanne, 12 February 2008. Source code + nice picture can be found here.
Nicolas Courtois, Gregory V. Bard and David Wagner:
Algebraic and Slide Attacks on KeeLoq. This paper
describes 1) the first successful algebraic attack in history on a full round
real-life block cipher 2) the fastest attack ever found on KeeLoq. The
complexity of the latter is about 2^28
KeeLoq encryptions on average, and can be even
2^23 for a fraction of keys (see our
next paper in preparation, not in FSE proceedings). The paper was
presented at Fast Software Encryption 2008, Lausanne, Switzerland, February
10-13, 2008, and appears in LNCS Springer, 2008.
See also a VERY OLD version, NOT up-to-date: eprint/2007/062/. Experimental algebraic cryptanalysis
of block ciphers - web
page.
Presentation
New Frontiers in Symmetric Cryptanalysis, from the
invited talk given by N. Courtois at at
ECRYPT workshop Tools for Cryptanalysis in Krakow, 24-25 September,
full version is
available here.
- Nicolas Courtois and Blandine Debraize: Specific S-box Criteria in Algebraic Attacks on Block Ciphers with Several Known Plaintexts, to appear in Post-Proceedings of WEWoRC 2007, Western European Workshop on Research in Cryptology, July 4-6, 2007, Ruhr-University Bochum, Germany. To appear in Springer LNCS 4945.
Full-page magazine article in Polish:
"Jak sie wlamac do samochodu znanej marki za pomoca kryptoanalizy?", in monthly
magazine of academics and students of Military University of Technology,
Warsaw, Poland, Nr 7-9, 136-138, July-September 200, page 12, ISSN 1507-9988.
Nicolas Courtois, Gregory V. Bard:
Algebraic Cryptanalysis of the Data Encryption Standard,
In 11-th IMA Conference, Cirencester, UK, 18-20 December 2007, Springer LNCS
4887.
Was also presented at ECRYPT workshop Tools for Cryptanalysis in Krakow, 24-25 September. See also eprint.iacr.org/2006/402/.Presentation
New Frontiers in Symmetric Cryptanalysis, from the talk
given by N. Courtois at rump session of Eurocrypt 2007,
available here.
Longer and different version was presented at
ECRYPT workshop Tools for Cryptanalysis and is
available here.
- Press report: w attacks on KeeLoq that is used to unlock doors and deactivate the alarm in many cars, see (in Polish) a report on IPSEC.PL online news service.
- Another report in Polish: "Czekasz chwile i wchodzisz do dowolnej limuzyny".
Nicolas Courtois, Gregory V. Bard,
Chris Jefferson: Efficient Methods for
Conversion and Solution of Sparse Systems of Low-Degree Multivariate
Polynomials over GF(2) via SAT-Solvers,
eprint/2007/024/. Will be
presented at ECRYPT
workshop Tools for Cryptanalysis in Krakow, 24-25 September.
