The U.S. government came to like the work of historian David Kahn, who passed away in 2024. The National Security Agency (NSA) honored him three times for his research on cryptography and espionage: with a "scholar-in-residence" title in 1993, a ceremony making his personal library part of the National Cryptological Museum in 2010, and a hall of fame induction in 2020.
But decades before, the U.S. government considered that personal library an alarming security threat. The FBI has declassified its files on Kahn, which Reason obtained under the Freedom of Information Act. Although it is publicly known that the NSA tried to stop Kahn from publishing his 1967 magnum opus, The Codebreakers, the new files show that Kahn had caught the feds' attention a decade before, with the case making its way up to FBI Director J. Edgar Hoover himself.
