Jacques Stern (born 21 August 1949) is a cryptographer, currently a professor at the ÃÂcole Normale Supérieure. He received the 2006 CNRS Gold medal. His notable work includes the cryptanalysis of numerous encryption and signature schemes, the design of the PointchevalâÂÂStern signature algorithm, the NaccacheâÂÂStern cryptosystem and NaccacheâÂÂStern knapsack cryptosystem, and the block ciphers CS-Cipher, DFC, and xmx. He also contributed to the cryptanalysis of the SFLASH signature scheme.