Lars Ramkilde Knudsen (born 21 February 1962) is a Danish researcher in

cryptography Cryptography, or cryptology (from "hidden, secret"; and ''graphein'', "to write", or ''-logy, -logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of Adversary (cryptography), ...

, particularly interested in the design and

analysis Analysis (: analyses) is the process of breaking a complex topic or substance into smaller parts in order to gain a better understanding of it. The technique has been applied in the study of mathematics and logic since before Aristotle (38 ...

block cipher In cryptography, a block cipher is a deterministic algorithm that operates on fixed-length groups of bits, called ''blocks''. Block ciphers are the elementary building blocks of many cryptographic protocols. They are ubiquitous in the storage a ...

hash functions A hash function is any function that can be used to map data of arbitrary size to fixed-size values, though there are some hash functions that support variable-length output. The values returned by a hash function are called ''hash values'', ...

and

message authentication code In cryptography, a message authentication code (MAC), sometimes known as an authentication tag, is a short piece of information used for authentication, authenticating and Data integrity, integrity-checking a message. In other words, it is used t ...

s (MACs).

Academic

After some early work in

banking A bank is a financial institution that accepts Deposit account, deposits from the public and creates a demand deposit while simultaneously making loans. Lending activities can be directly performed by the bank or indirectly through capital m ...

, Knudsen enrolled at

Aarhus University Aarhus University (, abbreviated AU) is a public research university. Its main campus is located in Aarhus, Denmark. It is the second largest and second oldest university in Denmark. The university is part of the Coimbra Group, the Guild, and Ut ...

in 1984 studying

mathematics Mathematics is a field of study that discovers and organizes methods, Mathematical theory, theories and theorems that are developed and Mathematical proof, proved for the needs of empirical sciences and mathematics itself. There are many ar ...

and

computer science Computer science is the study of computation, information, and automation. Computer science spans Theoretical computer science, theoretical disciplines (such as algorithms, theory of computation, and information theory) to Applied science, ...

, gaining an MSc in 1992 and a PhD in 1994. In 1999 he became a professor at the

University of Bergen The University of Bergen () is a public university, public research university in Bergen, Norway. As of 2021, the university had over 4,000 employees and 19,000 students. It was established by an act of parliament in 1946 consolidating several sci ...

Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...

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 In cryptography, SHA-1 (Secure Hash Algorithm 1) is a hash function which takes an input and produces a 160-bit (20-byte) hash value known as a message digest – typically rendered as 40 hexadecimal digits. It was designed by the United States ...

and MD2 hash functions, and a couple of block

cipher In cryptography, a cipher (or cypher) is an algorithm for performing encryption or decryption—a series of well-defined steps that can be followed as a procedure. An alternative, less common term is ''encipherment''. To encipher or encode i ...

s: DES, DFC,

IDEA In philosophy and in common usage, an idea (from the Greek word: ἰδέα (idea), meaning 'a form, or a pattern') is the results of thought. Also in philosophy, ideas can also be mental representational images of some object. Many philosophe ...

ICE Ice is water that is frozen into a solid state, typically forming at or below temperatures of 0 ° C, 32 ° F, or 273.15 K. It occurs naturally on Earth, on other planets, in Oort cloud objects, and as interstellar ice. As a naturally oc ...

LOKI Loki is a Æsir, god in Norse mythology. He is the son of Fárbauti (a jötunn) and Laufey (mythology), Laufey (a goddess), and the brother of Helblindi and Býleistr. Loki is married to the goddess Sigyn and they have two sons, Narfi (son of Lo ...

MISTY In cryptography, MISTY1 (or MISTY-1) is a block cipher designed in 1995 by Mitsuru Matsui and others for Mitsubishi Electric. MISTY1 is one of the selected algorithms in the European NESSIE project, and has been among the cryptographic tech ...

, RC2,

RC5 In cryptography, RC5 is a symmetric-key block cipher notable for its simplicity. Designed by Ronald Rivest in 1994, ''RC'' stands for "Rivest Cipher", or alternatively, "Ron's Code" (compare RC2 and RC4). The Advanced Encryption Standard (AES) ...

, RC6, SC2000, Skipjack,

Square In geometry, a square is a regular polygon, regular quadrilateral. It has four straight sides of equal length and four equal angles. Squares are special cases of rectangles, which have four equal angles, and of rhombuses, which have four equal si ...

and

SAFER Safer or SAFER may refer to: * FSO ''Safer'', a Yemeni floating oil storage and offloading vessel * Safer (surname) * Safar or safer, the second month of the Islamic calendar * As an acronym: ** SAFER, an initiative of the World Health Organizat ...

. Knudsen was involved in designing some ciphers: AES candidates

DEAL In cryptography, DEAL (Data Encryption Algorithm with Larger blocks) is a symmetric block cipher derived from the Data Encryption Standard (DES). Its design was presented by Lars Knudsen at the SAC conference in 1997, and submitted as a proposa ...

, Serpent (the latter in conjunction with Ross Anderson and

Eli Biham Eli Biham () is an Israeli cryptographer and cryptanalyst who is a professor at the Technion - Israel Institute of Technology Computer Science department. From 2008 to 2013, Biham was the dean of the Technion Computer Science department, afte ...

) and the lightweight cipher

PRESENT The present is the period of time that is occurring now. The present is contrasted with the past, the period of time that has already occurred; and the future, the period of time that has yet to occur. It is sometimes represented as a hyperplan ...

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 The NIST hash function competition was an open competition held by the US National Institute of Standards and Technology (NIST) to develop a new hash function called SHA-3 to complement the older SHA-1 and SHA-2. The competition was formally ann ...

(it was not the winner). He introduced the technique of

impossible differential cryptanalysis In cryptography, impossible differential cryptanalysis is a form of differential cryptanalysis for block ciphers. While ordinary differential cryptanalysis tracks differences that propagate through the cipher with greater than expected probability, ...

and

integral cryptanalysis In cryptography, integral cryptanalysis is a cryptanalytic attack that is particularly applicable to block ciphers based on substitution–permutation networks. It was originally designed by Lars Knudsen as a dedicated attack against Square, so ...

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.

References

External links

Homepage
* * {{DEFAULTSORT:Knudsen, Lars 1962 births Living people Modern cryptographers Danish scientists Danish computer scientists Academic staff of the University of Bergen Academic staff of the Technical University of Denmark Aarhus University alumni