David is a cryptographer and a professor at the École normale supérieure. He was previously a professor at Panthéon-Assas University. David is well known for his work in public-key cryptography, especially around the cryptanalysis of digital signature schemes. He co-designed the Naccache-Stern cryptosystem and the Naccache-Stern knapsack cryptosystem. David is also a visiting professor and researcher at the Information Security Group of Royal Holloway, University of London, and in 2020, was elected as a Fellow of the IACR.