VIC Cipher

Reino Häyhänen’s message found in a hollow nickel in Brooklyn (1953) resisted the FBI and NSA until he defected in 1957. Its keys came from a song, a date, his personal number and a keygroup by chain addition; a straddling checkerboard and two transpositions, one disrupted, followed. Kahn reconstructed every step; the app reproduces his 207 groups.

• David Kahn, “Number One From Moscow”, Studies in Intelligence 5:4 (1961)
• John J. G. Savard, “The VIC Cipher” (quadibloc.com), the worked English example