Nicolas Tadeusz Courtois (born 14 November 1971) is a

cryptographer Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or ''-logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of adver ...

and senior lecturer in computer science at

University College London , mottoeng = Let all come who by merit deserve the most reward , established = , type = Public research university , endowment = £143 million (2020) , budget = ...

. Courtois was one of the co-authors of both the

XSL attack In cryptography, the ''eXtended Sparse Linearization'' (XSL) attack is a method of cryptanalysis for block ciphers. The attack was first published in 2002 by researchers Nicolas Courtois and Josef Pieprzyk. It has caused some controversy as it was ...

against block ciphers, such as the

Advanced Encryption Standard The Advanced Encryption Standard (AES), also known by its original name Rijndael (), is a specification for the encryption of electronic data established by the U.S. National Institute of Standards and Technology (NIST) in 2001. AES is a varian ...

, and the XL system for solving systems of algebraic equations used in the attack. Other cryptographic results of Courtois include algebraic attacks on stream ciphers, attacks on the

KeeLoq KeeLoq is a proprietary hardware-dedicated block cipher that uses a non-linear feedback shift register (NLFSR). The uni-directional command transfer protocol was designed by Frederick Bruwer of Nanoteq (Pty) Ltd., the cryptographic algorithm wa ...

and Hitag 2 systems used for remote keyless automobile entry systems,. and an analysis of cryptographic weaknesses in

public transit Public transport (also known as public transportation, public transit, mass transit, or simply transit) is a system of transport for passengers by group travel systems available for use by the general public unlike private transport, typic ...

smart cards including the

London Underground The London Underground (also known simply as the Underground or by its nickname the Tube) is a rapid transit system serving Greater London and some parts of the adjacent counties of Buckinghamshire, Essex and Hertfordshire in England. The ...

Oyster card The Oyster card is a payment method for public transport in London (and certain areas around it) in England, United Kingdom. A standard Oyster card is a blue credit-card-sized stored-value contactless smart card. It is promoted by Transport ...

and the

Dutch Dutch commonly refers to: * Something of, from, or related to the Netherlands * Dutch people () * Dutch language () Dutch may also refer to: Places * Dutch, West Virginia, a community in the United States * Pennsylvania Dutch Country People E ...

OV-chipkaart The OV-chipkaart (short for ''openbaar vervoer chipkaart'', meaning ''public transport chipcard'') is a contactless smart card system used for all public transport in the Netherlands. First introduced in the Rotterdam Metro in April 2005, it has ...

. More recently, he has written about cryptocurrency. Courtois graduated from University of Paris VI: Pierre et Marie Curie, where he received his doctoral degree in cryptography.

References

Modern cryptographers French cryptographers 1971 births Living people {{crypto-bio-stub