Techniques for concealing the very existence of a message, such as invisible ink or microdots.
Definition based on the International Spy Museum glossary. The difference from encryption is fundamental: a cipher hides the content of a message, but not the fact that the message exists; steganography hides the message itself. In practice the two methods were combined.1
Examples from the records: according to the FBI, William Sebold, a German intelligence agent working under FBI control, was given microphotographs with enciphering instructions in Hamburg in 1940. According to an article by B. G. Royden in Studies in Intelligence, Adolf Tolkachev, a CIA source in Moscow, sent ordinary-looking letters to accommodation addresses containing messages written in invisible ink and additionally enciphered with a one-time pad.2,3
Sources
- International Spy Museum (Washington, DC), Language of Espionage (glossary)
- FBI, Famous Cases: Duquesne Spy Ring
- Barry G. Royden, ‘Studies in Intelligence’ 47 (3), 2003 (CIA), Tolkachev, A Worthy Successor to Penkovsky: An Exceptional Espionage Operation
Checked: 4 November 2026