It also inspired a growing community of private-sector cryptologists who, until then, had been stymied by the federal authorities. Until the late 1960s, anyone who submitted a patent for a cryptological device or technique would receive a visit from an agent; the government would even go so far as to hire such inventors — simply to gain control of their intellectual property.
“There was so little available about cryptography,” said Steven Levy, the author of “Crypto: How the Code Rebels Beat the Government Saving Privacy in the Digital Age” (2001), in an interview. “And when you got past the books for kids about using a wheel, decoder rings and things like that, the serious work was classified.”
But as Mr. Kahn argued in his book and elsewhere, cryptology needed to be free; the coming digital communications revolution and the need to keep such communications secure demanded it. By providing a detailed map of where cryptology had been, he motivated aspiring coders to push further — Mr. Kahn’s book, Mr. Levy said, was “their Bible.”
David Kahn was born on Feb. 7, 1930, in Manhattan and grew up in Great Neck, on the North Shore of Long Island. His mother, Florence (Abraham) Kahn, owned a glassmaking factory, and his father, Jesse Kahn, was a trial lawyer.
A chance encounter sparked David’s interest in codes. When he was a teenager, he spied a book in the Great Neck public library: “Secret and Urgent” (1939), by Fletcher Pratt, a history of secret codes filled with the sort of cloak-and-dagger intrigue that makes a heart race.