Arjen Klaas Lenstra (born 2 March 1956, in

Groningen Groningen (; gos, Grunn or ) is the capital city and main municipality of Groningen province in the Netherlands. The ''capital of the north'', Groningen is the largest place as well as the economic and cultural centre of the northern part of t ...

) is a Dutch mathematician, cryptographer and computational

number theorist Number theory (or arithmetic or higher arithmetic in older usage) is a branch of pure mathematics devoted primarily to the study of the integers and integer-valued functions. German mathematician Carl Friedrich Gauss (1777–1855) said, "Math ...

. He is currently a professor at the École Polytechnique Fédérale de Lausanne (EPFL) where he heads of the Laboratory for Cryptologic Algorithms.

Career

He studied mathematics at the University of Amsterdam. He is currently a professor at the EPFL ( Lausanne), in the Laboratory for Cryptologic Algorithms, and previously worked for

Citibank Citibank, N. A. (N. A. stands for " National Association") is the primary U.S. banking subsidiary of financial services multinational Citigroup. Citibank was founded in 1812 as the City Bank of New York, and later became First National City ...

and Bell Labs.

Research

Lenstra is active in cryptography and

computational number theory In mathematics and computer science, computational number theory, also known as algorithmic number theory, is the study of computational methods for investigating and solving problems in number theory and arithmetic geometry, including algorithms ...

, especially in areas such as

integer factorization In number theory, integer factorization is the decomposition of a composite number into a product of smaller integers. If these factors are further restricted to prime numbers, the process is called prime factorization. When the numbers are suf ...

. With

Mark Manasse Mark may refer to: Currency * Bosnia and Herzegovina convertible mark, the currency of Bosnia and Herzegovina * East German mark, the currency of the German Democratic Republic * Estonian mark, the currency of Estonia between 1918 and 1927 * Fi ...

, he was the first to seek volunteers over the internet for a large scale volunteer computing project. Such projects became more common after the Factorization of RSA-129 which was a high publicity distributed factoring success led by Lenstra along with

Derek Atkins Derek A Atkins is a computer scientist specializing in computer security. He studied electrical engineering and computer science at the Massachusetts Institute of Technology. In June 2014, he became the chief technology officer of SecureRF. At ...

, Michael Graff and Paul Leyland. He was also a leader in the successful factorizations of several other RSA numbers. Lenstra was also involved in the development of the number field sieve. With coauthors, he showed the great potential of the algorithm early on by using it to factor the ninth Fermat number, which was far out of reach by other factoring algorithms of the time. He has since been involved with several other number field sieve factorizations including the current record, RSA-768. Lenstra's most widely cited scientific result is the first polynomial time algorithm to factor polynomials with rational coefficients in the seminal paper that introduced the LLL lattice reduction algorithm with

Hendrik Willem Lenstra Hendrik Willem Lenstra Jr. (born 16 April 1949, Zaandam) is a Dutch mathematician. Biography Lenstra received his doctorate from the University of Amsterdam in 1977 and became a professor there in 1978. In 1987 he was appointed to the faculty of ...

and László Lovász. Lenstra is also co-inventor of the

XTR In cryptography, XTR is an algorithm for public-key encryption. XTR stands for 'ECSTR', which is an abbreviation for Efficient and Compact Subgroup Trace Representation. It is a method to represent elements of a subgroup of a multiplicative group of ...

cryptosystem In cryptography, a cryptosystem is a suite of cryptographic algorithms needed to implement a particular security service, such as confidentiality (encryption). Typically, a cryptosystem consists of three algorithms: one for key generation, one for ...

. On 1 March 2005, Arjen Lenstra,

Xiaoyun Wang Wang Xiaoyun (; born 1966) is a Chinese cryptographer, mathematician, and computer scientist. She is a professor in the Department of Mathematics and System Science of Shandong University and an academician of the Chinese Academy of Sciences. Ear ...

, and Benne de Weger of

Eindhoven University of Technology The Eindhoven University of Technology ( nl, Technische Universiteit Eindhoven), abbr. TU/e, is a public technical university in the Netherlands, located in the city of Eindhoven. In 2020–21, around 14,000 students were enrolled in its BSc a ...

demonstrated construction of two X.509 certificates with different public keys and the same MD5 hash, a demonstrably practical

hash collision In computer science, a hash collision or hash clash is when two pieces of data in a hash table share the same hash value. The hash value in this case is derived from a hash function which takes a data input and returns a fixed length of bits. Al ...

. The construction included private keys for both public keys.

Distinctions

Lenstra is the recipient of the

RSA Award for Excellence in Mathematics RSA may refer to: Organizations Academia and education * Rabbinical Seminary of America, a yeshiva in New York City *Regional Science Association International (formerly the Regional Science Association), a US-based learned society *Renaissance S ...

2008 Award.RSA Conference Awards

Private life

Lenstra's brother and co-author Hendrik Lenstra is a professor in mathematics at

Leiden University Leiden University (abbreviated as ''LEI''; nl, Universiteit Leiden) is a Public university, public research university in Leiden, Netherlands. The university was founded as a Protestant university in 1575 by William the Silent, William, Prince o ...

and his brother

Jan Karel Lenstra Jan Karel Lenstra (born 19 December 1947, in Zaandam) is a Dutch mathematician and operations researcher, known for his work on scheduling algorithms, local search, and the travelling salesman problem. Lenstra received his Ph.D. from the Univers ...

is a former director of

Centrum Wiskunde & Informatica The (abbr. CWI; English: "National Research Institute for Mathematics and Computer Science") is a research centre in the field of mathematics and theoretical computer science. It is part of the institutes organization of the Dutch Research Cou ...

(CWI).

References

External links