Christina Boura

I hold since 2013 a position of Maître de Conférences in Computer Science at  Laboratoire de Mathématiques de Versailles (LMV) of Université de Versailles Saint-Quentin-en-Yvelines. My research lies mainly in the area of symmetric-key cryptography and cryptanalysis.


Contact:
Équipe CRYPTO - LMV
Université de Versailles Saint-Quentin-en-Yvelines
Bureau 306 A, Bât. Descartes,
45, avenue des États-Unis,
78035 Versailles Cedex, France
Tel : (+33) 1 39 25 43 23
Email: christina.boura@uvsq.fr

Students

PhD Students
  • 2020-2022: Margot Funk (UVSQ)
  • 2020-2022: Rachelle-Heim Boissier (UVSQ)
  • 2018-2020: Daniel Coggia (Inria), Cryptanalysis techniques for lightweight encryption schemes. Defended on October 8, 2021.
Master Students
  • 2021: Margot Funk (UVSQ), Cryptanalysis of the hash function Troïka.
  • 2018: Daniel Coggia (Inria), On subspace-trail cryptanalysis.
  • 2018: Florian Wartelle (Inria), Searching a counter-example to the conjecture APN=CAPN for odd n.

Publications

Journal Papers
  • Christina Boura and Daniel Coggia. « Efficient MILP Modelings for Sboxes and Linear Layers of SPN ciphers ». In IACR Transactions on Symmetric Cryptology, 2020(3), 327-361. pdf
  • Shizhu Tian, Christina Boura and Léo Perrin. « Boomerang Uniformity of Popular S-box Constructions ». In Designs, Codes and Cryptography, 88(9): 1959-1989 (2020). pdf
  • Christina Boura, Nicolas Gama, Mariya Georgieva and Dimitar Jetchev. « CHIMERA: Combining Ring-LWE-based Fully Homomorphic Encryption Schemes ». In Journal of Mathematical Cryptology. Volume 14, Issue 1, Pages 316–338 (2020). pdf
  • Christina Boura, Eirini Chavli and Maria Chlouveraki. « The BMM symmetrising trace conjecture for the exceptional 2-reflection groups of rank 2 ». In Journal of Algebra  558, Special issue in honor of Michel Broué, 176-198 (2020). pdf
  • Christina Boura, Eirini Chavli, Maria Chlouveraki and Konstantinos Karvounis. « The BMM Symmetrising Trace Conjecture for groups G4, G5, G6, G7, G8 ». In J. Symb. Comput. 96:62-84 (2020). pdf
  • Christina Boura, Anne Canteaut and Daniel Coggia. « A General Proof Framework for Recent AES Distinguishers ». In IACR Transactions of Symmetric Cryptology, 2019(1), 170-191. pdf
  • Christina Boura and Anne Canteaut. « On the Boomerang Uniformity of Cryptographic Sboxes ». In IACR Transactions on Symmetric Cryptology, 2018(3), 290-310. pdf
  • Christina Boura, Anne Canteaut, Jérémy Jean and Valentin Suder. « Two Notions of Differential Equivalence on Sboxes ». Designs, Codes and Cryptography, 87(2-3): 185-202 (2019). pdf
  • Christina Boura, Virginie Lallemand, Maria Naya-Plasencia and Valentin Suder. « Making the impossible possible ». In Journal of Cryptology 31(1): 101-133 (2018). pdf
  • Christina Boura, Anne Canteaut, Lars R. Knudsen and Gregor Leander. « Reflection ciphers ». In Designs, Codes and Cryptography 82(1-2): 3-25, 2017. pdf
  • Christina Boura and Anne Canteaut. « On the influence of the algebraic degree of $F^{-1}$ on the algebraic degree of $G circ F$. » In IEEE Transactions on Information Theory 59(1): 691-702, 2013. pdf
Papers in International Peer-Reviewed Conference Proceedings
  • Christina Boura, Rachelle Heim-Boissier and Yann Rotella. « Breaking Panther ». Africacrypt 2022, to appear. pdf
  • Christina Boura, Nicolas Gama, Mariya Georgieva and Dimitar Jetchev. « Simulating Homomorphic Evaluation of Deep Learning Prediction ». In CSCML 2019: 212-230. pdf
  • Christina Boura, Ilaria Chillotti, Nicolas Gama, Dimitar Jetchev, Stanislav Peceny and Alexander Petric. « High-Precision Privacy-Preserving Real-Valued Function Evaluation ». In Financial Crypto 2018, volume 10957 of Lecture Notes in Computer Science, pages 183-202, 2018. pdf
  • Christina Boura and Anne Canteaut. « Another view of the division property ». In CRYPTO 2016, volume 9814 of Lecture Notes in Computer Science (Part I), pages 654-682, 2016. pdf, slidesvideo
  • Christina Boura, Avik Chakraborti, Gaëtan Leurent, Goutam Paul, Dhiman Saha, Hadi Soleimany and Valentin Suder. « Key Recovery Attack against 2.5-round pi-Cipher ». In Fast Software Encryption-FSE 2016, volume 8783 of Lecture Notes in Computer Science, pages 535-553, 2016. pdf
  • Christina Boura, Maria Naya-Plasencia and Valentin Suder. « Scrutinizing and Improving Impossible Differential Attacks: Applications to CLEFIA, Camellia, LBlock and Simon ». In ASIACRYPT 2014,  volume 8873 of Lecture Notes in Computer Science, pages 179-199, 2014. pdf
  • Andrey Bogdanov, Christina Boura, Vincent Rijmen, Meiqin Wang, Long Wen and Jingyuan Zhao. « Key Difference Invariant Bias in Block Ciphers ». In ASIACRYPT 2013,  volume 8269 of Lecture Notes in Computer Science, pages 357-376, 2013. pdfslides
  • Christina Boura and Anne Canteaut. « A new criterion for avoiding the propagation of linear relations through an Sbox. » In Fast Software Encryption-FSE 2013, volume 8424 of Lecture Notes in Computer Science, pages 585-604, 2013. pdfslidesvideo
  • Christina Boura, Sylvain Lévêque and David Vigilant. « Side-Channel Analysis of Grøstl and Skein ». In the Proceedings of the 2nd International Workshop on Trustworthy Embedded Devices-TrustED 2012, IEEE Symposium on Security and Privacy, pages 6-26, May 2012. pdf
  • Christina Boura, Anne Canteaut and Christophe De Cannière. « Higher-Order Differential Properties of Keccak and Luffa ». In Fast Software Encryption-FSE 2011, volume 6733 of Lecture Notes in Computer Science, pages 252-269, 2011. pdfslides
  • Christina Boura and Anne Canteaut. « Zero-Sum Distinguishers for Iterated Permutations and Application to Keccak-f and Hamsi-256 ». In Selected Areas in Cryptography-SAC 2010, volume 6544 of Lecture Notes in Computer Science, pages 1-17 2010. pdfslides
  • Christina Boura and Anne Canteaut. « A zero-sum property for the Keccak-f permutation with 18 rounds ». In International Symposium on Information Theory-ISIT 2010, pages 2488-2492, IEEE 2010. pdfslides 
Papers in International Workshops
  • Christina Boura, Léo Perrin and Shizhu Tian. « Boomerang Uniformity of Popular S-box Constructions. In Proceedings of the Eleventh International Workshop on Coding and Cryptography (WCC) 2019, March 31 – April 5, 2019.
  • Christina Boura, Anne Canteaut, Jérémy Jean and Valentin Suder. « Two Notions of Differential Equivalence on Sboxes « . In Proceedings of the Tenth International Workshop on Coding and Cryptography (WCC) 2017, September, 18-22, 2017. slides
  • Christina Boura, Anne Canteaut, Lars R. Knudsen and Gregor Leander. « Reflection ciphers ». In Proceedings of the Ninth International Workshop on Coding and Cryptography (WCC) 2015, Paris, April 13-17, 2015. slides
  • Vincent Grosso, Christina Boura, Benoît Gérard and François-Xavier Standaert. « A note on the Empirical Evaluation of Security Margins against Algebraic Attacks (with Application to Low Cost Ciphers LED and Piccolo) ». In Proceedings of the 33rd WIC Symposium on Information Theory in the Benelux, pages 52-59, Boekelo, The Netherlands, May 2012. pdf
  • Christina Boura and Anne Canteaut. « On the Algebraic Degree of some SHA-3 Candidates ». In Proceedings of the Third SHA-3 Candidate Conference, Washington D.C, March 22-23, 2012
  • Christina Boura and Anne Canteaut. « On the Algebraic Degree of Iterated Permutations ». Finite Fields and Applications-Fq10, Gent, Belgium, July 2011.
Technical Reports
  • Christina Boura. « Analyse de fonctions de hachage cryptographiques ». PhD thesis (in French) 2012. pdfslides.
  • Christina Boura. « D2.1: Intermediate results on physical analysis of phase 2 candidates ». Technical report for the French National ANR Project SAPHIR2 (Security Analysis of Hash Functions), July 2012. pdf
  • Christina Boura and Jérémy Jean. « D2.2/D3.1: Final results on cryptanalysis of NIST hash candidates ». Technical report for the French National ANR Project SAPHIR2 (Security Analysis of Hash Functions), November 2012. pdf
  • Christina Boura, Bart Mennink, Maria Naya Plasencia and Christian Rechberger « D.SYM.11: Final Hash Functions Status Report ». Technical Repport for ECRYPT II, January 2013. pdf

Invited Talks and Seminars

  • May 21, 2021. « Aspects of modern symmetric-key cryptography ». Webinar for the computer science and the maths departments of the University of Thessaly, invited presentation (in Greek).
  • November 2, 2020. « New MILP Modelings for Symmetric-Key Primitives ». Webinar for the cryptography group of Institute of Information Engineering, Chinese Academy of Sciences, China, invited presentation.
  • October 22, 2020. « New MILP Modelings for Symmetric-Key Primitives ». Seminar Mathématiques discrètes, codes et cryptographie , Paris 8, invited presentation.
  • August 6, 2020. « New MILP Modelings for Symmetric-Key Primitives ». Webinar Cryptography, Network Security and Cybersecurity, by the Department of Information Technology, Maulana Abul Kalam Azad University of Technology, West Bengal, India in association with Islamic University of Science and Technology, Jammu and Kashmir, India, invited presentation. slides
  • December 15, 2017. « Two Notions of Differential Equivalence on Sboxes ». Seminar of the CRYPTO group, LMV, UVSQ, invited presentation. slides
  • January 16, 2017. « New techniques and improved complexity analysis of impossible differential attacks ». Early Symmetric Crypto (ESC) event, Canach, Luxembourg, invited presentation. slides
  • November 24, 2015. « The division property: A new attack against block ciphers ». Seminar of the group Algebra and Geometry, LMV, UVSQ, invited presentation. slides 
  • October 1, 2015. « Understanding the division property ». Invited talk at 5th Asian Workshop on Symmetric Key Cryptography – ASK 2015, Singapour. slides 
  • June 12, 2015. « Improving impossible differential cryptanalysis ». Séminaire CCA (Codage, Cryptologie, Algorithmes), Paris, France, invited presentation. slides
  • January 9, 2015. « Algebraic properties of SHA-3 and notable cryptanalysis results ». Invited talk at International Conference on Mathematics and Computing – ICMC 2015, Haldia, India. slides 
  • November 29, 2012. « The new standard for hash functions ». Seminar of the group Combinatoire et Algorithmes, Rennes, invited presentation. slides
  • January 15, 2012. « New bounds on the algebraic degree of iterated permutations. » Cryptography Seminar of Rennes, invited presentation. slides
  • November 15, 2011. « Cryptographic Hash Functions ». INRIA’s Junior Seminar. slides
  • November 10, 2011. « New bounds on the algebraic degree of iterated permutations. » Cryptography Seminar of Caen, invited presentation. slides

Summer Schools

  • CryptoBG 2018, Oriahovitza, Bulgaria, July 8-15 2018. Block Ciphers and Boolean Functions for Symmetric Cryptography (4.5 hours). slides
  • École de Printemps en Codage et Cryptographie, La Chapelle Gauthier (Seine et Marne), May 17-20, 2016. Introductory course in Symmetric Cryptography (4.5 hours). slides
  • IceBreak 2013, Reykjavik, Iceland, June 6-12 2013. One-hour course on the algebraic degree of symmetric primitives. slides
  • CryptoBG 2013, Oriahovitza, Bulgaria, July 14-21 2013. Introductory course in Symmetric Cryptography (4.5 hours).

Editorial Board

I’m serving as co-editor-in-chief for FSE 2023 and ToSC 2022/2023.


Program Committees

Between 2017 and 2020 and again since 2021 I am/was a member of the editorial board of the IACR Transactions on Symmetric Cryptology .

  • Asiacrypt 2022, Taipei, Taiwan, December 2022.
  • WTSC22 (International Workshop on Trusted Smart Contracts), Grenada, May 6, 2022.
  • ICMC 2022 (8th International Conference on Mathematics and Computing), Vellore Institute of Technology, Vellore, Tamil Nadu, India, January 6-8, 2022.
  • ICSP 2021 (International Conference of Security and Privacy), Jamshedpur, India, November 16-17, 2021.
  • Indocrypt 2021, LNMIIT, Jaipur, December 12-15, 2021.
  • CSCML 2021 (International Symposium of Cyber Security Cryptology and Machine Learning), Be’er Sheva, Israel, July 8-9, 2021.
  • WTSC21 (International Workshop on Trusted Smart Contracts), Grenada, March 5, 2021.
  • ICMC 2021, (7th International Conference on Mathematics and Computing), online, March 2-5, 2021.
  • Eurocrypt 2021, Zagreb, Croatia, October 17-21, 2021.
  • WTSC20 (International Workshop on Trusted Smart Contracts), Kota Kinabalu, Sabah, Malaysia, February 14, 2020.
  • CSCML 2020 (International Symposium of Cyber Security Cryptology and Machine Learning), Be’er Sheva, Israel, July 2-3, 2020.
  • Journées Nationales « Codage et Cryptographie », online, November 2-6, 2020.
  • ICMC 2020, (6th International Conference on Mathematics and Computing), Sikkim University, Gangtok, Sikkim, India, March 18-20, 2020.
  • FSE 2020, online, November 9-13, 2020.
  • Eurocrypt 2019, Darmstadt, Germany, May 19-23, 2019.
  • FSE 2019, Paris, France, March 25-28, 2019.
  • WTSC19 (International Workshop on Trusted Smart Contracts), St. Kitts, February 18-22, 2019.
  • ICMC 2019, (5th International Conference on Mathematics and Computing), School of Computer Engineering, KIIT, February 6-9, 2019.
  • Indocrypt 2018, New Delhi, India, December 9-12, 2018.
  • ICMC 2018, (4th International Conference on Mathematics and Computing), Varanasi, India, January 9-11, 2018.
  • FSE 2018, Bruges, Belgium, March 4-7, 2018.
  • Journées Nationales « Codage et Cryptographie, Vosges, France, April 23-28, 2017
  • FSE 2017, Tokyo, Japan, March 5-8, 2017.
  • ICMC 2017, (3rd International Conference on Mathematics and Computing), Haldia, India, January 17-21, 2017.
  • FSE 2016, Bochum, Germany, March 20-23, 2016.
  • Indocrypt 2014, New Delhi, India, December 14-17, 2014.
  • SAC 2014, Montreal, Canada, August 14-15, 2014.
  • MoCrySEn 2013, Regensburg, Germany, September 2-6, 2013.

PhD Committees 

  • Victor Mollimard, « Algorithmes pour la cryptanalyse différentielle ». The PhD defence took place at Irisa, Rennes on January 11, 2022.
  • Eliane Koussa, « Analyse et conception d’algorithmes de cryptographie post-quantique ». The PhD defence took place at UVSQ on December 18, 2020.
  • Paul Huynh, « Analyse et Conception d’Algorithmes de Chiffrement Légers ». The PhD defence took place online on November 26, 2020.
  • Sébastien Duval, « Constructions pour la cryptographie à bas coût ». The PhD defence took place at Inria de Paris on Octobre 3, 2018.
  • Roberto Civino, « Differential attacks using alternative operations and block cipher design ». The PhD defence took place at University of Trento, Italy, on March 6, 2018. (I was a reviewer for this PhD).
  • Sukhendu Kuila, « Cryptanalysis of Round-Reduced SHA-3 Standards ». The PhD defence took place at Vidyasagar University, Midnapore, West Bengal, India in May 2016. (I was a reviewer for this PhD).

Selection Committees 

  • 2015: Université de Limoges (assistant professor position)
  • 2017: Université de Limoges (assistant professor position)
  • 2017: Université de Rouen (assistant professor position)
  • 2021: Concours Chargés de Recherche (CR) / ISFP, centre Inria Saclay
  • 2022: Université Grenoble Alpes (assistant professor position)

Teaching

  • 2013-2022: Cryptographie.  Licence 3 d’informatique et double licence bio-info, Département Informatique de l’Université de Versailles-Saint-Quentin en Yvelines (cours et TDs)
  • 2015-2017 and 2020-2022: Analyse d’algorithmes et programmation. M1 MINT, Département de Mathématiques de l’Université de Versailles-Saint-Quentin en Yvelines, (cours et TDs). Depuis 2020, j’enseigne ce cours avec Yann Rotella.
  • 2019-2021: Algèbre Commutative et Effective.  M2 Algèbre Appliquée, Département de Mathématiques de l’Université de Versailles-Saint-Quentin en Yvelines (TDs).
  • 2015-2021: Maths pour l’info.  Licence 2 Info/Bio-info, Département Informatique de l’Université de Versailles-Saint-Quentin en Yvelines (cours de TDs).
  • 2020-2021: Fondements de l’informatique (Python). Licence 1, Département Informatique de l’Université de Versailles-Saint-Quentin en Yvelines (cours).
  • 2014-2016: Programmation Orientée Objet (POO) et Java, Licence 2 d’informatique, Département Informatique de l’Université de Versailles-Saint-Quentin en Yvelines (cours de TDs). J’ai enseigné ce cours avec Stéphane Lopes.