But the unmasking of many previously redacted names has revealed the identities of people who worked with the clandestine services, roles that in many cases were hidden for decades even from close family members.

History buffs dove into thousands of pages of government records released online this week, hoping for new nuggets about President John F. Kennedy’s assassination. They instead found revelations about U.S. espionage in the massive document dump that also exposed some previously redacted personal information.