Quagmire III

IDquagmire-316 / 69classical · polyalphabetic

Cipher / Polyalphabetic

Quagmire III

One keyed alphabet on both sides of the tableau.

Keyspace: 26! × 26^indicatorLength
Decode: same options back
Works on: A-Z, the rest passes
Family: 14 in polyalphabetic

required 2 / 3

Options

keystring: required; Keyword for both alphabets, the rest of A-Z after it
indicatorstring: required; Indicator keyword, written down the column under indicatorUnder: each letter sets the cipher row for one letter of the text, in turn
indicatorUnderstring: default A; The plain letter the indicator keyword stands under

Access

Createcreate("quagmire-3")

CLIciphers encode quagmire-3 'THE SAME KEYED ALPHABET' --key AUTOMOBILE --indicator HIGHWAY

Tryplayground with the sample above

Kinvigenere, gronsfeld, beaufort, porta +9

Quagmire III keys both alphabets with the same word. AUTOMOBILE gives AUTOMBILECDF…, on top and underneath. The indicator runs down the column under plain A, as in Quagmire I.

const quagmire = create("quagmire-3"); const keys = { key: "AUTOMOBILE", indicator: "HIGHWAY" }; quagmire.encode("the same keyed alphabet", keys).text; // "krs lwmi tjdvi abmrgqmt" quagmire.decode("KRSLWMITJDVIABMRGQMTM", keys).text; // "THESAMEKEYEDALPHABETI"

From the ACA's example, period 7. See the second H in HIGHWAY? Rows one and four are the same row. Nobody minds.

Why does it feel like Vigenère?

Because it is one, wearing a name tag. Swap every letter for its place in the keyed alphabet and Quagmire III turns into a plain Vigenère. Solve that, and the keyword falls out of the alphabet you rebuilt along the way.