Jacques Stern (born 1949) is a cryptographer, currently a professor at the École Normale Supérieure, where he is Director of the Computer Science Laboratory. He received the 2006 CNRS Gold Medal. His notable work includes the cryptanalysis of numerous encryption and signature schemes, the design of the Pointcheval–Stern signature algorithm, the Naccache–Stern cryptosystem and Naccache–Stern knapsack cryptosystem, and the block ciphers CS-Cipher, DFC, and xmx.