Arjen K. Lenstra is Professor of Computer Science at École Polytechnique Fédérale de Lausanne. His research focuses on cryptography and computational number theory, especially in areas such as integer factorization. He was closely involved in the development of the number field sieve method for integer factorization as well as several other cryptologic results. He is the recipient of the Excellence in the Field of Mathematics RSA Conference 2008 Award and a Fellow of the International Association for Cryptologic Research (IACR).