Even if a multitude of independent alphabets is used, periodic polyalphabetic encryption contains one element which is difficult to hide: the number of keys in the period of the encryption. This is based on the following stationariness property of stochastic sources: If P is a plaintext (of length M) from a source Q, then P( s ), the plaintext P shifted cyclically by any number s of positions, is from the same source.
KeywordsKappa Test Punch Card Encryption Step Perforated Sheet Stochastic Source
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- 1.William F. Friedman, Military Cryptanalysis, War Department, Office of the Chief Signal Officer. Washington, D.C.: U.S. Government Printing Office. Vol. I: Monoalphabetic Substitution Systems 1938, 1942. Vol. II: Simpler Varieties of Polyalphabetic Substitution Systems 1938, 1943. Vol. III: Simpler Varieties of Aperiodic Substitution Systems 1938, 1939. Vol. IV: Transposition and Fractionating Systems 1941. A copy is in the University of Pennsylvania Library, Philadelphia, PA.Google Scholar
- 2.W. Heath Robinson was a British cartoonist who drew magnificent and lovely but impractical machines for all possible and impossible tasks. There were copies of HEATH ROBINSON called PETER ROBINSON and ROBINSON AND CLEAVER—names of London department stores, and (Michie) also SUPER ROBINSON.Google Scholar
- 3.Said to be named after Rube Goldberg, American counterpart to Heath Robinson. Possibly an allusion to Emanuel Goldberg, an inventor of photoelectric sensingGoogle Scholar