FoundationsFoundationsIdeas that show up in more than one cipher family.Also found as basics · mathematical foundationsIdeas shared by several ciphersMany classical ciphers reuse the same ideas: numbered alphabets, fixed replacements, repeating Keys, and grids. Once you know what those operations do, the named methods are much easier to tell apart.Friedman, Codes and CiphersFoundationUsed byAlphabets and modular arithmeticCaesar, Vigenère, Beaufort, Variant Beaufort, GronsfeldMonoalphabetic substitutionCaesar, general simple substitution, PolybiusPeriodic KeysVigenère, Beaufort, Variant Beaufort, GronsfeldTranspositionkeyed columnar transpositionSquares and pairsPlayfair and PolybiusBiliteral systemsBaconianSourcesWilliam F. Friedman, Codes and Ciphers (Cryptology)PreviousDictionaryNextAlphabets and symbol values