Nicolas T. COURTOIS' research in cryptography

Nicolas Courtois: Faster Attacks on Full GOST. A short presentation presented at FSE 2012 rump session, available here.

Nicolas T. Courtois, Theodosis Mourouzis and Pho V. Le Extension of de Weger�s Attack on RSA with Large Public Keys, . In SECRYPT 2012, 24-27 July, Rome, Italy. here.

Nicolas T. Courtois, Daniel Hulme, Theodosis Mourouzis: Multiplicative Complexity and Solving Generalized Brent Equations With SAT Solvers. In COMPUTATION TOOLS 2012, The Third International Conference on Computational Logics, Algebras, Programming, Tools, and Benchmarking, July 22-27, 2012 - Nice, France. Published in: conference, ISBN: 978-1-61208-222-6, Pages: 22 to 27, Copyright: Copyright (c) IARIA, 2012, Date: 22 July 2012, full paper vailable here. We have received the Best Paper Award.

Nicolas Courtois: An Improved Differential Attack on Full GOST. 15 March 2012, preprint available here.

Nicolas Courtois: Algebraic Complexity Reduction and Cryptanalysis of GOST. The "master paper" preprint, with a lot of additional material, available here.

Nicolas Courtois: Security Evaluation of GOST 28147-89 In View Of International Standardisation In Cryptologia, Volume 36, Issue 1, pp. 2-13, 2012. Available here. An older version of this report was also presented to the experts of International Standards Organisation (ISO) involved in the standardisation of GOST through two member countries, and this version is available at: eprint.iacr.org/2011/211/.

Nicolas T. Courtois, Pouyan Sepherdad, Petr Susil and Serge Vaudenay: ElimLin Algorithm Revisited . In FSE 2012, Springer. .

Nicolas T. Courtois, Daniel Hulme, Theodosis Mourouzis: Solving Circuit Optimisation Problems in Cryptography and Cryptanalysis. In SHARCS 2012, workshop without formal proceedings, 70 participants, Washington DC, 17-18 March 2012. On page 179 of the workshop record. .

Nicolas T. Courtois, Daniel Hulme and Theodosis Mourouzis: Solving Circuit Optimisation Problems in Cryptography and Cryptanalysis, . Appears in electronic proceedings of 2nd IMA Conference Mathematics in Defence 2011, 20 October 2011, Defence Academy of the United Kingdom, Swindon, UK. The initial short 6-page version is found at here. A longer version is available at eprint: eprint/2011/475/.

Nicolas T. Courtois, Gregory V. Bard and Daniel Hulme: A New General-Purpose Method to Multiply 3x3 Matrices Using Only 23 Multiplications, . At arxiv.1108.2830.

Ravi Jhawar, Philip Inglesant, Martina Angela Sasse, and Nicolas Courtois: Make Mine a Quadruple: Strengthening the Security of Graphical One-Time PIN Authentication . In NSS 2011, 5th International Conference on Network and System Security, Milan, Italy, September 6-8, 2011.

Nicolas Courtois: Algebraic Complexity Reduction and Weak Keys in GOST . Preprint.

Nicolas Courtois: Cryptanalysis of Two GOST Variants With 128-bit Keys . Preprint.

Nicolas Courtois, Michal Misztal: Differential Cryptanalysis of GOST. Preprint, work in progress. At eprint.iacr.org/2011/312/ .
Nicolas Courtois, Michal Misztal: First Differential Attack On Full 32-Round GOST. Accepted at ICICS'11, Thirteenth International Conference on Information and Communications Security, November 23-26, 2011, Beijing, China. Springer LNCS 7043. .
Nicolas Courtois, Michal Misztal: Aggregated Differentials and Cryptanalysis of PP-1 and GOST. in 11th Central European Conference on Cryptology, will be held in Debrecen, Hungary, on June 30 - July 2, 2024.
Nicolas Courtois, Theodosis Mourouzis: Black-Box Collision Attacks on the Compression Function of the GOST Hash Function Accepted as SHORT paper at the 6th International Conference on Security and Cryptography SECRYPT 2011, 18-21 July, Seville, Spain.
Nicolas T. Courtois and Gregory V. Bard Random Permutation Statistics and An Improved Slide-Determine Attack on KeeLoq To appear in special volume Quisquater Festschrift Springer LNCS 6805, 2011.
Gregory Bard, Nicolas Courtois, Jorge Nakahara Jr, Pouyan Sepehrdad and Bingsheng Zhang: Algebraic, AIDA/Cube and Side Channel Analysis of KATAN Family of Block Ciphers. In Indocrypt 2010, December 12-15, 2010, Hyderabad, India, Springer LNCS.
Gregory V. Bard, Shaun V. Ault and Nicolas T. Courtois: Statistics of Random Permutations and the Cryptanalysis Of Periodic Block Ciphers . Accepted and will appear in Cryptologia in 2011.
Nicolas T. Courtois, Keith Jackson and David Ware: Fault-Algebraic Attacks on Inner Rounds of DES. In eSmart 2010, European Smart Card Security Conference, 22-24 September 2010, Sophia Antipolis, French Riviera, with web proceedings (slides presented available here ).
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 5735, pp. 167-176.
Nicolas T. Courtois: Self-similarity Attacks on Block Ciphers and Application to KeeLoq, was once presented at a the International Workshop on Coding and Cryptography in Norway in May 2009, is present in printed pre-proceedings but was withdrawn from printed final proceedings. In special volume Quisquater Festschrift, LNCS vol. 6805, Springer, 2011, David Naccache editor.
Nicolas T. Courtois, Sean O'Neil and Jean-Jacques Quisquater: Practical Algebraic Attacks on the Hitag2 Stream Cipher in RFID Transponders. In eSmart 2009, European Smart Card Security Conference, 22-25 September 2009, Sophia Antipolis, French Riviera, with proceedings being published as a CD-ROM (slides presented).
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, appears in SECRYPT 2009 - International Conference on Security and Cryptography: 7-10 July 2009, Milan, Italy. Also known as "Courtois dark side" attack on MiFare Classic. Here are the slides). 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).
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 realize 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 in Snow 2.0. , In ICICS 2008, 10th International Conference on Information and Communications Security, 20 - 22 October, 2008, Birmingham, UK. Will appear in LNCS, Springer. (slides presented available here ). 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.
C�me Berbain, Olivier Billet, Anne Canteaut, Nicolas Courtois, Henri Gilbert, Louis Goubin, Aline Gouget, Louis Granboulan, C�dric Lauradoux, Marine Minier, Thomas Pornin and Herv� Sibert: Sosemanuk , a Fast Software-Oriented Stream Cipher, In New Stream Cipher Designs, The eSTREAM Finalists, LNCS 4986, pp. 98-118, Springer, 2008.
C�me Berbain, Olivier Billet, Anne Canteaut, Nicolas Courtois, Blandine Debraize, Henri Gilbert, Louis Goubin, Aline Gouget, Louis Granboulan, C�dric Lauradoux, Marine Minier, Thomas Pornin and Herv� 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, 41 (2008), pp. 167-188, post-proceedings of Tatracrypt 2007 conference.
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. And here are the slides.
See also a VERY OLD version, NOT up-to-date: eprint/2007/062/.
Experimental algebraic cryptanalysis of block ciphers - web page.
Nicolas Courtois: New Frontier in Symmetric Cryptanalysis , slides from an invited talk by N. Courtois at Indocrypt 2008, 14-17 December 2008, slides are available here
Slides by Nicolas Courtois: New Frontiers in Symmetric Cryptanalysis, from the invited talk given by N. Courtois 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/ . Also presented at ECRYPT workshop Tools for Cryptanalysis in Krakow, 24-25 September. A working Windows distribution with source code can be found here (it requires careful manual installation). .

Nicolas T. Courtois: How Fast can be Algebraic Attacks on Block Ciphers?, in online proceedings of Dagstuhl Seminar 07021 "Symmetric Cryptography" 07-12 January 2007, E. Biham, H. Handschuh, S. Lucks, V. Rijmen (Eds.), available here. ISSN 1862 - 4405, 2007. Also available from eprint.iacr.org/2006/168.
Invited talk at CLC 2006, Darmstadt, Germany 25-27 September 2006.
Nicolas Courtois, Blandine Debraize and Eric Garrido: On Exact Algebraic [Non-]Immunity of S-boxes Based on Power Functions, eprint/2005/203/. In ACISP 2006, 11th Australasian Conference on Information Security and Privacy. 3 - 5 July 2006. Melbourne. Australia.
New methods for attacking block ciphers, article in Polish "Nowe metody atak�w na szyfry blokowe", In Security - Computerworld polish edition, 3 April 2006.
Nicolas Courtois: Cryptanalysis of Sfinks, eprint/2005/243/. In ICISC 2005, LNCS 3935, Springer.
Nicolas Courtois, Louis Goubin: An Algebraic Masking Method to Protect AES Against Power Attacks, eprint/2005/204/. In ICISC 2005, LNCS 3935, Springer.
Nicolas Courtois: The Best Differential Characteristics and Subtleties of the Biham-Shamir Attacks on DES, eprint/2005/202/.
Fast Moving Fronts in Computer Science: interview published on the internet on 1st of July 2005, read it here.
C. Berbain, O. Billet, A. Canteaut, N. Courtois, H. Gilbert, L. Goubin, A. Gouget, L. Granboulan, C. Lauradoux, M. Minier, T. Pornin, and H. Sibert: SOSEMANUK, a fast software-oriented stream cipher, submission to ECRYPT call for stream ciphers and presented at SKEW 2005 workshop in Aarhus, Denmark on 26 May 2005.
C. Berbain, O. Billet, A. Canteaut, N. Courtois, H. Gilbert, L. Goubin, A. Gouget, L. Granboulan, C. Lauradoux, M. Minier, T. Pornin, and H. Sibert: DECIM, a new stream cipher for hardware applications, submission to ECRYPT call for stream ciphers and presented at SKEW 2005 workshop in Aarhus, Denmark on 27 May 2005.
Aline Gouget, Herv� Sibert, C�me Berbain, Nicolas Courtois, Blandine Debraize, Chris Mitchell: Analysis of the Bit-Search Generator and sequence compression techniques, FSE 2005, LNCS 3557, pp. 196-214, Springer, 2006.
Nicolas Courtois: Algebraic Attacks on Combiners with Memory and Several Outputs, In ICISC 2004, LNCS, Springer. The extended and recently updated version of this paper is available at eprint.iacr.org/2003/125/.
Nicolas Courtois, Feistel Schemes and Bi-Linear Cryptanalysis, In Crypto 2004, LNCS 3152, pp. 23-40, Springer. The extended version is available at eprint.iacr.org/2005/251/.
Nicolas Courtois, The Inverse S-box and Two Paradoxes of Whitening, Presented at the Rump Session of Crypto 2004. Here is the long, very much extended version of the slides.
Jiun-Ming Chen, Nicolas Courtois and Bo-Yin Yang: On Asymptotic Security Estimates in XL and Gr�bner Bases-Related Algebraic Cryptanalysis, In ICICS'04, LNCS 3269, pp. 401-413, Springer, 2004.
Nicolas Courtois, Short Signatures, Provable Security, Generic Attacks and Computational Security of Multivariate Polynomial Schemes such as HFE, Quartz and Sflash, draft, eprint 2004/143.
Nicolas Courtois, The Inverse S-box, Non-linear Polynomial Relations and Cryptanalysis of Block Ciphers, in AES 4 Conference, Bonn May 10-12 2004, LNCS 3373, pp. pp. 170-188, Springer. Available for Springer subscribers. Full version is available here.
Nicolas Courtois, General Principles of Algebraic Attacks and New Design Criteria for Components of Symmetric Ciphers. Invited talk, AES 4 Conference, Bonn May 10-12 2004, LNCS 3373, pp. 67-83, Springer. Available for Springer subscribers. Full version is available here.
Patent: Nicolas Courtois: Proc�d� de protection d'un ensemble cryptographique par masquage homographique, European Patent Application 04291204.8-, filled on 11.05.04.
Nicolas Courtois, Louis Goubin and Jacques Patarin: SFLASHv3, a fast asymmetric signature scheme available on eprint.iacr.org/2003/211/. This paper specifies the new version of Sflash. The previous version is no longer recommended. Sflash-v3 should remain the fastest signature scheme known and can only be rivalled by NTRU.
Nicolas Courtois: Algebraic Attacks over GF(2^k), Application to HFE Challenge 2 and Sflash-v2. PKC 2004, LNCS, Springer. Warning: all numeric complexity estimates of this paper are out of date.
Nicolas Courtois, Guilhem Castagnos and Louis Goubin: What do DES S-boxes Say to Each Other ? Available on eprint.iacr.org/2003/184/. This paper exhibits some structure in the DES S-boxes, probably nothing serious. It also introduces a new type of algebraic attack on block ciphers.
Press Article:
In New Scientist, 07 June 2003 issue, page 36, Dana Mackenzie, describes the current situation regarding the security of world encryption standards, as "A Game of Chance". A short abstract of this article can be found here.
Nicolas Courtois: Fast Algebraic Attacks on Stream Ciphers with Linear Feedback. Crypto 2003, August 17-21 2003, LNCS 2729, pp. 177-194, Springer.
Nicolas Courtois, Willi Meier: Algebraic Attacks on Stream Ciphers with Linear Feedback. Eurocrypt 2003, LNCS 2656, pp. 345-359, Springer. IMPORTANT: Here is the long extended version of the paper. and here are EXTENDED SLIDES from 2005 with a lot of added material.
Nicolas Courtois, Robert T. Johnson, Pascal Junod, Thomas Pornin and Michael Scott: Did Filiol Break AES ? Available at eprint.iacr.org/2003/022/. See also this page.
Nicolas Courtois, Jacques Patarin: About the XL Algorithm over GF(2), in Cryptographers' Track RSA 2003, April 13-17, San Francisco, LNCS 2612, pages 141-157, Springer.
Nicolas Courtois: Higher Order Correlation Attacks, XL algorithm, and Cryptanalysis of Toyocrypt. Will be presented at 5th International Conference on Information Security and Cryptology (ICISC 2002), November 28-29, 2002, Seoul, Korea, LNCS 2587, pp. 182-199, Springer.
See also my web page page about algebraic attacks on stream ciphers.
Nicolas Courtois, Josef Pieprzyk: Cryptanalysis of Block Ciphers with Overdefined Systems of Equations; (or the XSL attack on block ciphers), in Asiacrypt 2002, LNCS 2501, pp.267-287, Springer.
Two different versions of the XSL attack are available on eprint.iacr.org.
Here is my AES / Rijndael page with the latest news about algebraic attacks on AES. This page is frequently updated.
Press Release: "Strict codes observed at conference", by Leah McFall, a report about Courtois and Pieprzyk attack on AES, appeared in Otago Daily, New Zealand, during the Asiacrypt 2002 conference, Tuesday, 3-December 2002, page 15. Read it here.
Press Release: Hank Wolfe speaks about the weakness of AES: "Code-breakers may have found US computer weakness", by Joanna Norris, in Otago Daily, New Zealand, Friday, 29-November 2002.
Press Release: "Crucial Cipher Flawed, Cryptographers Claim", by Charles Seife, Science Magazine, 27 September 2002, page 2193.
AES News: a Cryptogram article by Bruce Schneier, 15 September 2002. Some related comments etc.
An article entitled Comment Tout Dire Sans Rien R�v�ler, published special issue of the French magazine Pour La Science (French edition of Scientific American), available everywhere in France in July-October 2002.
Nicolas Courtois, Magnus Daum and Patrick Felke: On the Security of HFE, HFEv- and Quartz, PKC 2003, LNCS 2567, Springer, pp. 337-350. An extended version can be found on eprint.
Patent: Nicolas Courtois: Proc�d� de protection d'un ensemble cryptographique par masquage multivariable lin�aire, European Patent Application 02291625.8-, filled on 28.06.02, Priority FRA 0205486, filled on 30.04.02.
Patent: Mehdi-Laurent Akkar, Nicolas Courtois and Louis Goubin: Proc�d� et syst�me de g�n�ration de signature, European Patent Application 02292253.8, filled on 13.09.02.
Mehdi-Laurent Akkar, Nicolas Courtois, Louis Goubin, Romain Duteuil, A Fast and Secure Implementation of Slash, PKC 2003, LNCS 2567, Springer, pp. 267-278. See also the Sflash web page.
Nicolas Courtois: Generic Attacks and the Security of Quartz, PKC 2003, LLNCS 2567, Springer, pp. 351-364. A preliminary version has been presented at the second Nessie workshop, September 13th 2001, Royal Holloway, University of London. Download the extended version of the paper / download my PKC presentation.
Nicolas Courtois, Louis Goubin, Willi Meier, Jean-Daniel Tacier:
Solving Underdefined Systems of Multivariate Quadratic Equations;
PKC 2002, Paris, February 2002, LNCS 2274, pp. 211-227, Springer.
Nicolas Courtois: The security of cryptographic primitives based on multivariate algebraic problems: MQ, MinRank, IP, HFE. PhD thesis, Paris 6 university, September 25th 2001, in French, under the direction of Sami HARARI. The PhD thesis is available here. And here are slides from my PhD defense.
Nicolas Courtois, Matthieu Finiasz and Nicolas Sendrier:
How to achieve a McEliece-based Digital Signature Scheme.
The McEliece signature scheme paper published at Asiacrypt 2001, LNCS 2248, Springer, pp. 157-174. An early version was published as Inria rapport de recherche 4118, February 2001. And here are the slides presented at the rump session of Crypto 2001. Check also the homepage of McEliece signature scheme.
Nicolas Courtois: Efficient Zero-knowledge authentication based on a linear algebra problem MinRank. Presented at the Asiacrypt 2001, LNCS 2248, Springer, pp. 402-421. The full paper is available at the iacr server, download directly the ps/pdf file. Here is the presentation from Asiacrypt 2001
A preliminary version was presented at the Rump Session of Crypto 2000 and also at the PKC&CNT conference. Here is the official MinRank home page.
A slide showing some difficult problems and reductions known in multivariate cryptography.
Patent: Nicolas Courtois and Jacques Patarin: Anti-Pirate Method for the Distribution of Digital Content, European Patent 02788390.9-2415-IB0205520, filled on 19.12.02, Priority FRA 0116585 filled on 12.02.01.
A web page presenting the GPT cryptosystem.
Nicolas Courtois: The security of Hidden Field Equations (HFE), Cryptographers' Track Rsa Conference 2001, LNCS 2020, pp. 266-281, Springer-Verlag. Donwload the paper hfesec.dvi / hfesec.ps / hfesec.pdf.
The slides on HFE security from RSA2001: hfesecsl.dvi / hfesecsl.ps / hfesecsl.pdf.
Comments: This paper describes a subexponential attack on HFE and is the best attack ever found on HFE and HFE Challenge 1. At Crypto 2003 Joux and Faug�re will explain why this attack works and improve it slightly. See also the "official" HFE cryptosystem home page.
Nicolas Courtois, Louis Goubin and Jacques Patarin: Quartz, 128-bit long digital signatures, submitted to Nessie European Call for Primitives, and also published in Cryptographers' Track Rsa Conference 2001, LNCS 2020, pp.282-297, Springer-Verlag.
The official homepage for Quartz .
Nicolas Courtois, Louis Goubin and Jacques Patarin: Flash, a fast multivariate signature algorithm, submitted to Nessie European Call for Primitives, and also published in Cryptographers' Track Rsa Conference 2001, LNCS 2020, pp. 298-307, Springer.
The official homepages for Flash/Sflash.
Nicolas Courtois: On multivariate signature-only public key cryptosystems,
paper available at eprint.iacr.org/2001/029/.
My talk Hfe and MinRank at the PKC&CNT conference. hfemr.dvi/hfemr.ps/hfemr.pdf
Nicolas Courtois and Louis Goubin: The Cryptanalysis of TTM
Asiacrypt 2000 conference, Asiacrypt'2000, LNCS 1976, Springer, pp.44-57.
Slides from Asiacrypt 2000 talk on the cryptanalysis of TTM.
A web page about TTM.
My talk from the Enigma 2000 conference (in Polish),
Nicolas Courtois: Algorytm klucza publicznego HFE, corrected and extended, hfepl.ps.
An intoduction to multivariate cryptography, (in Polish), presented also at the Enigma 2000 conference (in Polish),
Nicolas Courtois: Kryptografia Wielu Zmiennych, corrected and extended kurs.pdf
Nicolas Courtois, Alexander Klimov, Jacques Patarin, and Adi Shamir:
Efficient Algorithms for Solving Overdefined Systems of Multivariate Polynomial Equations, Eurocrypt 2000, LNCS 1807, Springer, pp. 392-407.
The extended version of the paper is available here.
Here are slides from my talk at Eurocrypt 2000 (but does not include 2 slides I made by hand).
Mes transparents (en fran�ais) sur HFE et polyn�mes multivariables (Batz-sur-Mer, 1er Juin 1999). Corrig�.
English-French-Polish cryptology dictionary .
Nicolas Courtois, Louis Goubin and Jacques Patarin: C*-+ and HM - Variations around two schemes of T. Matsumoto and H. Imai; Asiacrypt' 98, Springer, pp.35-49.
Here is the extended version of the paper dvi / ps / pdf.
Nicolas Courtois, Louis Goubin and Jacques Patarin: Improved Algorithms for Isomorphism of Polynomials. Eurocrypt'98, Springer, pp.184-200.
Here is the extended version of the paper as a dvi/ ps or pdf file.
Here are slides from my talk at Eurocrypt'98.
Nicolas Courtois: Extensive study of Isomorphism of Polynomials and Asymmetric Cryptography (1997),
Download it's abstract (English/French).
Or the whole work in French (quite out of date now).
Nicolas Courtois: Article Metoda Hylemorficzna presented at VIth Philosophical Symposium, Toru�, Poland, September 7th 1995.
Nicolas Courtois: Report on the cryptanalysis of the HARALIA cryptosystem (1995).
You can download it's abstract (English/French) and introduction (in French).
Nicolas Courtois: A student project about Quantum teleportation (EPR pairs) - scanned bad quality .gif in french and quite out of date (1993).
A short note about protecting radio communications from eavesdropping, published in the "Pomysly" of the popular Polish magazine "Mlody Technik", in the early 80s.