Short answers, pulled from the story.
Secrecy exists as a practice of hiding information from those without a need to know. Claude Shannon proposed three systems of secrecy within communication in 1948 including concealment, privacy, and true secrecy systems.
The landmark legal case United States v. Reynolds decided by the Supreme Court in 1953 upheld U.S. Government rights regarding military secrecy. This ruling occurred on the 8th of March 1953 after extensive deliberation.
Most nations enforce Official Secrets Acts like the Espionage Act in the United States requiring individuals to obtain security clearances to access classified material stored in safes. Critical Nuclear Weapon Design Information enjoys near-universal agreement regarding its secrecy needs while many countries limit government secrecy through laws like the U.S. Freedom of Information Act.
Organizations ranging from multi-national corporations to nonprofit charities keep secrets for competitive advantage. New products under development and unique manufacturing techniques qualify as trade secret law protections while financial reports stay secret during preparation to limit insider trading opportunities.
Claude Shannon proposed three systems of secrecy within communication in 1948 including concealment, privacy, and true secrecy systems. Concealment systems include invisible ink and fake covering cryptograms that hide the message's very existence while privacy systems require special equipment like voice inversion to recover the original signal.