Lars Ramkilde Knudsen

"Lars Knudsen" redirects here. For the film producer, see Lars Knudsen (producer).

Not to be confused with Lars Knutsen.

Lars Ramkilde Knudsen (born 21 February 1962) is a Danish researcher in cryptography, particularly interested in the design and analysis of block ciphers, hash functions and message authentication codes (MACs).

Lars R. Knudsen
Born	(1962-02-21) 21 February 1962 (age 63)
Nationality	Danish
Alma mater	Aarhus University
Scientific career
Fields	Cryptography
Institutions	Technical University of Denmark
Doctoral advisor	Ivan Damgård

Academic

After some early work in banking, Knudsen enrolled at Aarhus University in 1984 studying mathematics and computer science, gaining an MSc in 1992 and a PhD in 1994. In 1999 he became a professor at the University of Bergen, Norway and in 2001 he became a professor at the Technical University of Denmark (DTU). Ivan Damgård was Lars' mentor during his studies at Aarhus University.

Publications

Knudsen has published a couple of papers on cryptanalysis of cryptographic primitives, including the R-MAC scheme, the SHA-1 and MD2 hash functions, and a couple of block ciphers: DES, DFC, IDEA, ICE, LOKI, MISTY, RC2, RC5, RC6, SC2000, Skipjack, Square and SAFER.

Knudsen was involved in designing some ciphers: AES candidates DEAL, Serpent (the latter in conjunction with Ross Anderson and Eli Biham) and the lightweight cipher PRESENT included in ISO/IEC 29192-2:2019. He was involved in designing Grøstl, a hash function which was one of the submissions to the NIST SHA-3 competition (it was not the winner).

He introduced the technique of impossible differential cryptanalysis^[1] and integral cryptanalysis.

Industry and Research Contributions

Knudsen is a co-founder at Dencrypt A/S and PiiGuard ApS, companies specializing in secure communication technologies. He has secured multiple research grants, including those for “Quantum Safe Cryptography” and “Post-Quantum Secure Symmetric Cryptography.” His work has significantly influenced the development of secure encryption standards. Knudsen has been an editor for journals such as IEEE Transactions on Information Forensics and Security and Design, Codes and Cryptography. He has also chaired a number of international cryptography conferences, including FSE 1999, Eurocrypt 2002 and SAC 2012.

Awards and Recognitions

In August 2021, Knudsen was knighted as Ridder af Dannebrog. He has been a Fellow of the International Association of Cryptologic Research (IACR) since 2013 and a member of the Danish Academy of Technical Sciences (ATV) since 2005.