Lars Knudsen

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Lars Knudsen

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

Denmark

Denmark is a Scandinavian country in northern Europe and the senior member of the Kingdom of Denmark. It is the southernmost of the Nordic countries....
researcher in cryptography

Cryptography

Cryptography is the practice and study of hiding information. In modern times cryptography is considered a branch of both mathematics and computer science and is affiliated closely with information theory, computer security and engineering....
, particularly interested in the design and analysis

Cryptanalysis

Cryptanalysis is the study of methods for obtaining the meaning of encrypted information, without access to the secret information which is normally required to do so....
of block cipher

Block cipher

In cryptography, a block cipher is a symmetric key algorithm cipher which operates on fixed-length groups of bits, termed blocks, with an unvarying transformation....
s, hash functions

Cryptographic hash function

A cryptographic hash function is a algorithm that takes an arbitrary block of data and returns a fixed-size bit string, the hash value, such that an accidental or intentional change to the data will almost certainly change the hash value....
and message authentication code

Message authentication code

A cryptography message authentication code is a short piece of information used to authenticate a message.A MAC algorithm accepts as input a secret key and an arbitrary-length message to be authenticated, and outputs a MAC ....
s (MACs).

r some early work in banking, Knudsen enrolled at Aarhus University in 1984 studying mathematics

Mathematics

Mathematics is the study of quantity, structure, space, change, and related topics of pattern and form. Mathematicians seek out patterns whether found in numbers, space, natural science, computers, imaginary abstractions, or elsewhere....
and computer science

Computer science

Computer science is the study of the theoretical foundations of information and computation, and of practical techniques for their implementation and application in computer systems....
, gaining an MSc in 1992 and a PhD in 1994.

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Encyclopedia

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

Denmark

Denmark is a Scandinavian country in northern Europe and the senior member of the Kingdom of Denmark. It is the southernmost of the Nordic countries....
researcher in cryptography

Cryptography

Cryptanalysis

Cryptanalysis is the study of methods for obtaining the meaning of encrypted information, without access to the secret information which is normally required to do so....
of block cipher

Block cipher

In cryptography, a block cipher is a symmetric key algorithm cipher which operates on fixed-length groups of bits, termed blocks, with an unvarying transformation....
s, hash functions

Cryptographic hash function

Message authentication code

Academic

After some early work in banking, Knudsen enrolled at Aarhus University in 1984 studying mathematics

Mathematics

Computer science

University of Bergen

The University of Bergen is located in Bergen, Norway, Norway. Although founded as late as 1946, academic activity had taken place at Bergen Museum as far back as 1825....
, Norway

Norway

Norway , officially the Kingdom of Norway, is a constitutional monarchy in Northern Europe that occupies the western portion of the Scandinavian Peninsula....
. Currently, Knudsen is a professor in the Department of Mathematics

Mathematics

Technical University of Denmark

The Technical University of Denmark was founded in 1829 as the 'College of Advanced Technology' . The initiative was taken by the renowned physicist Hans Christian ?rsted who also served as its Principal until his death in 1851....
. His Erdös Number is 3 , via his work with noted cryptographers Don Coppersmith

Don Coppersmith

Don Coppersmith is a cryptographer and mathematician. He was involved in the design of the Data Encryption Standard block cipher at IBM, particularly the design of the S-box, strengthening them against differential cryptanalysis....
and Ivan Damgård

Ivan Damgård

Ivan Damg?rd is a professor at the University of Aarhus in Denmark. He researches and teaches cryptography and is known among other things for the Merkle-Damg?rd construction used in most modern cryptographic hash functions such as SHA-1 and MD5....
. Ivan was Lars' teacher and mentor during his studies at Aarhus University, and according to Lars was a deciding factor in his choice to study differential cryptanalysis

Differential cryptanalysis

Differential cryptanalysis is a general form of cryptanalysis applicable primarily to block ciphers, but also to stream ciphers and cryptographic hash functions....
. His Ph.D. was refereed by Bart Preneel

Bart Preneel

Bart Preneel is a Belgium cryptographer and cryptanalyst. He is a professor at Katholieke Universiteit Leuven, in the COSIC group, president of the International Association for Cryptologic Research, and project manager of ECRYPT....
.

Publications

Knudsen has published analyses of a wide variety of cryptographic designs, including the RMAC scheme, the SHA-1 and MD2

MD2

Message Digest Algorithm 2 is a cryptographic hash function developed by Ronald Rivest in 1989. The algorithm is optimized for 8-bit computers....
hash functions, and at least a dozen block cipher

Cipher

In cryptography, a cipher is an algorithm for performing encryption and decryption — a series of well-defined steps that can be followed as a procedure....
s: DES

Data Encryption Standard

The Data Encryption Standard is a block cipher that was selected by National Bureau of Standards as an official Federal Information Processing Standard for the United States in 1976 and which has subsequently enjoyed widespread use internationally....
, DFC

DFC (cipher)

In cryptography, DFC is a block cipher which wascreated in 1998 by a group of researchers from ?cole Normale Sup?rieure, CNRS, and France T?l?com and submitted to the AES competition....
, IDEA, ICE

ICE (cipher)

In cryptography, ICE is a block cipher published by Kwan in 1997. The algorithm is similar in structure to Data Encryption Standard, but with the addition of a key-dependent bit permutation in the round function....
, LOKI

Loki

File:Loke og Sigyn by Eckersberg.jpgIn Norse mythology, Loki is a ?ss or j?tunn . Loki's relation with the gods varies by source. Loki assists the gods, and sometimes causes problems for them....
, MISTY

Misty

Misty may refer to:* Misty of Chincoteague, a book by Marguerite Henry** Misty , an adaptation of the book* Misty * Misty , by Erroll Garner...
, RC2

RC2

In cryptography, RC2 is a block cipher designed by Ron Rivest in 1987. "RC" stands for "Ron's Code" or "Rivest Cipher"; other ciphers designed by Rivest include RC4 , RC5 and RC6....
, RC5

RC5

In cryptography, RC5 is a block cipher notable for its simplicity. Designed by Ron Rivest in 1994, RC stands for "Rivest Cipher", or alternatively, "Ron's Code" ....
, RC6

RC6

In cryptography, RC6 is a symmetric key block cipher derived from RC5. It was designed by Ron Rivest, Matt Robshaw, Ray Sidney, and Yiqun Lisa Yin to meet the requirements of the Advanced Encryption Standard AES competition....
, SC2000

SC2000

In cryptography, SC2000 is a block cipher invented by a research group at Fujitsu Labs. It was submitted to the NESSIE project, but was not selected....
, Skipjack

Skipjack (cipher)

In cryptography, Skipjack is a block cipher — an algorithm for encryption — developed by the United States National Security Agency ....
, Square

Square (cipher)

In cryptography, Square is a block cipher invented by Joan Daemen and Vincent Rijmen. The design, published in 1997, is a forerunner to the Rijndael algorithm, which has been adopted as the Advanced Encryption Standard....
and SAFER

SAFER

In cryptography, SAFER is the name of a family of block ciphers designed primarily by James Massey on behalf of Cylink Corporation. The early SAFER K and SAFER SK designs share the same encryption function, but differ in the number of rounds and the key schedule....
—it has been hinted that the "SK" in the "SAFER-SK" variant means Stop Knudsen after he had found weaknesses in a previous version.

Knudsen has also designed ciphers, including the AES candidates DEAL

Deal

Deal may refer to:* Deal , an automobile built in Jonesville, Michigan, from 1905 to 1911* Deal, Kent, a town in Kent, England* Deal, New Jersey, a Borough in Monmouth County, New Jersey, United States...
and Serpent

Serpent (cipher)

Serpent is a symmetric key block cipher which was a finalist in the Advanced Encryption Standard process, where it came second to Rijndael. Serpent was designed by Ross Anderson, Eli Biham, and Lars Knudsen....
(the latter in conjunction with Ross Anderson

Ross Anderson

Ross John Anderson is a researcher, writer, and industry consultant in security engineering.He is Professor in security engineering at the University of Cambridge University of Cambridge Computer Laboratory, where he is engaged in the ....
and Eli Biham

Eli Biham

Eli Biham is an Israeli cryptographer and Cryptanalysis, currently a professor at the Technion Israeli Institute of Technology Computer Science department....
).

He introduced the technique of impossible differential cryptanalysis

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, impossible differential cryptanalysis exploits differences that are impossible at some interme...
and integral cryptanalysis

Integral cryptanalysis

In cryptography, integral cryptanalysis is a cryptanalysis that is particularly applicable to block ciphers based on substitution-permutation networks....
.

Lars Knudsen

Academic

Publications

External links