David Naccache is a cryptographer, currently a professor at the Pantheon-Assas Paris II University and member of the École normale supérieure's Computer Laboratory. He is also a visiting professor at Royal Holloway University of London's Information Security Group. He received his Ph.D. in 1995 from the École nationale supérieure des télécommunications. Naccache's most notable work includes the design of the SHACAL block ciphers with Helena Handschuh as well as substantial work in public-key cryptography, including the cryptanalysis of digital signature schemes. Together with Jacques Stern he designed the similarly named but very distinct Naccache-Stern cryptosystem and Naccache-Stern knapsack cryptosystem.
In 2004 David Naccache and Claire Whelan, then employed by Gemplus International, used image processing techniques to uncover redacted information from the declassified 6 August 2001 President's Daily Brief Bin Ladin Determined To Strike in US. They also demonstrated how the same process could be applied to other redacted documents.[1]