Lenstra received his Ph.D. in mathematics from the Universiteit van Amsterdam in 1977. He was a full professor at the university from 1978 until 1986, and then at the University of California, Berkeley, from 1987 until 2003, and since 1998 at the Universiteit Leiden in the Netherlands. Lenstra is best known for introducing advanced techniques in the area of number-theoretic algorithms. These techniques have important applications in computer security. Lenstra has been a member of the Royal Dutch Academy of Science since 1984 and a fellow of the American Academy of Arts and Sciences since 1996. In 1998, he won the Spinoza Award, the highest scientific honor in the Netherlands.