Fractional substitution, meaning of,

Fractional substitutions,

-

Frequency (see

)

Frequency counts,

,

,

,

,

“Frequential checkerboard,”

German field cipher (the ADFGVX),

Grandpré’s word-square,

-

Graph, graphic appearance,

,

,

Grille, Fleissner’s,

Grille, Richelieu’s,

Grille, Sacco’s indefinite,

Grille, turning,

Gronsfeld cipher,

Group-application in polyalphabetic ciphers,

Group percentages (see

)

Hermann cipher,

Index-letter (or cell),

,

,

,

,

Indicators,

,

Intervals, alphabetical and lineal,

,

,

,

Intervals in cryptograms,

,

Inverse alphabets,

Irregular transposition,

-

Isolating a cipher alphabet,

Kasiski method,

Key, meaning of,

Key-alphabet,

“Key-frame” (or “skeleton”),

,

,

Key-interruption,

Key-length,

,

,

,

,

Key-lengthening devices in Vigenère,

Key-letter,

“Key-phrase” cipher,

Keys for simple substitution,

Keys, preparation of,

,

,

,

Keys, recovery of,

,

,

,

,

,

,

-

,

,

,

,

,

,

,

,

,

,

-

,

-

,

Keywords, uses of,

,

,

,

Knight’s tour,

Legrand’s open-letter cipher,

Levine’s concealment ciphers,

“Lining up” frequency counts,

-

Low-frequencies, assistance from,

,

,

,

,

,

Low-frequency contacts,

,

Magic squares,

Mathematical aspects of multiple-alphabet ciphers,

,

,

,

Mechanical methods,

,

,

,

-

,

,

,

Military aspects of ciphers,

,

Mirabeau’s cipher,

Mixed alphabets,

,

Monoalphabetic substitution, meaning of,

Morse alphabet,

“Multifid” alphabets,

Multi-literal substitutes,

,

,

Multiple-alphabet ciphers,

-

Multiple-alphabet substitution, meaning of,

Multiple messages,

,

,

,

,

Multiple-substitutional encipherment, Multiple substitutes,

,

,

,

,

Myszkowsky’s transposition,

Negative, or empty, words,

“Nicodemus” cipher,

Nihilist number-cipher,

-

Nihilist transposition cipher,

,

Novelty ciphers,

,

Null cipher,

Nulls, legitimate uses of,

,

,

,

Nulls, meaning of,

Numbers and symbols, encipherment of,

Numbers used as substitutes,

-

,

-

Ohaver method for period finding,

Open-letter cipher,

Pair-count,

Pair-encipherment,

,

,

Parallel frequency counts,

,

,