INDEX

Bassières processes for autokey,

[147]

[151]

Beaufort ciphers,

[121]

“Bifid” substitution,

Book cipher,

“Caesar” alphabets,

, 118,

Characteristics of systems,

, 105,

“Checkerboard” alphabets,

Cipher, meaning of,

Cipher alphabets,

Cipher disks,

Cipher disks, special application of,

[192]

Classification of ciphers,

Classification of substitutions,

Code,

Collon systems,

Columnar transposition,

Columnar transposition, double,

[54]

“Columns” in autokeyed ciphers,

Combination block,

Combination cipher,

Complements, complementary alphabets,

[123]

Complete-unit transposition,

[9]

Concealment cipher, meaning of,

Concealment ciphers,

[8]

Consonant-line method for simple substitution,

Contact count,

Conventional writing,

“Crypt,”

[72]

[91]

Cryptanalysis, meaning of,

[3]

Cryptogram, meaning of,

Cryptographic security,

[2]

Cycle (see

period

unit

)

Cyclical encipherment,

[186]

[200]

Deciphering alphabet (or key),

[71]

[104]

Decipherment, meaning of,

Decoding, meaning of,

[2]

Decrypt, meaning of,

Definitions, miscellaneous,

Dictionary cipher,

Digram, meaning of,

Digram count,

Digram-solution method for simple substitution,

Digram tests,

Dissimulated writing,

Double-key substitution, meaning of,

Double Myszkowsky transposition,

[60]

Double substitutions,

[155]

[193]

Double transpositions,

[18]

[54]

Empty, or negative, words,

[76]

Encipherment, meaning of,

Encoding, meaning of,

[2]

“Entry,”

[74]

Equivalent slide (or alphabet),

[180]

Factoring, in transpositions,

[12]

[42]

Factoring of intervals to find a period,

[128]

[132]

“Force Method,”

[90]

Fractional substitution, meaning of,

Fractional substitutions,

[209]

[212]

Frequency (see

statistics

)

Frequency counts,

“Frequential checkerboard,”

[105]

German field cipher (the ADFGVX),

Grandpré’s word-square,

[104]

[105]

Graph, graphic appearance,

Grille, Fleissner’s,

Grille, Richelieu’s,

Grille, Sacco’s indefinite,

[12]

Grille, turning,

[26]

Gronsfeld cipher,

[117]

Group-application in polyalphabetic ciphers,

[185]

Group percentages (see

statistics

)

Hermann cipher,

[143]

Index-letter (or cell),

Indicators,

Intervals, alphabetical and lineal,

Intervals in cryptograms,

[43]

[127]

Inverse alphabets,

[69]

Irregular transposition,

[37]

[67]

Isolating a cipher alphabet,

Kasiski method,

Key, meaning of,

Key-alphabet,

“Key-frame” (or “skeleton”),

Key-interruption,

Key-length,

Key-lengthening devices in Vigenère,

[143]

Key-letter,

“Key-phrase” cipher,

[103]

Keys for simple substitution,

[69]

Keys, preparation of,

Keys, recovery of,

Keywords, uses of,

Knight’s tour,

Legrand’s open-letter cipher,

[5]

Levine’s concealment ciphers,

[7]

“Lining up” frequency counts,

[162]

[163]

Low-frequencies, assistance from,

Low-frequency contacts,

[78]

[174]

Magic squares,

[10]

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,

[209]

Multi-literal substitutes,

[6]

[7]

[104]

Multiple-alphabet ciphers,

[197]

Multiple-alphabet substitution, meaning of,

Multiple messages,

Multiple-substitutional encipherment, Multiple substitutes,

Myszkowsky’s transposition,

[51]

Negative, or empty, words,

[76]

“Nicodemus” cipher,

[216]

Nihilist number-cipher,

[168]

Nihilist transposition cipher,

Novelty ciphers,

Null cipher,

Nulls, legitimate uses of,

Nulls, meaning of,

Numbers and symbols, encipherment of,

[101]

Numbers used as substitutes,

Ohaver method for period finding,

Open-letter cipher,

Pair-count,

Pair-encipherment,

Parallel frequency counts,

“Pattern words,”

Pentagram, meaning of,

Periodic ciphers,

[184]

“Period” in autokey ciphers,

Period, periodicity,

“Phillips” cipher,

Phonetic alphabets,

Playfair cipher,

“Pointers” for vowel-spotting,

[78]

Pollux systems,

[209]

Polyalphabetic ciphers, names of,

Polyalphabetic substitution, meaning of,

Polyalphabetic substitutions,

Polybius square,

Polygram substitution, meaning of,

Polygram substitutions,

[198]

[208]

Porta cipher,

[118]

Primary cipher alphabet,

Primary cryptogram (see

double transpositions

double substitutions

)

Probable word methods,

Progression, Progression index,

[192]

Puncture cipher,

“Quagmires” cipher,

[182]

“Rail fence” transpositions,

[12]

Reciprocal substitution,

Rectangular transposition,

[11]

“Route cipher,”

[14]

Route transposition,

[11]

“Running down the alphabet,”

“Running key,”

Saint-Cyr cipher,

Scytale,

Secondary cipher alphabets,

Sequence (see

statistics

)

Seriation, Seriation index,

[207]

Shift, Shifted alphabets,

Short word method for divided cryptograms,

[72]

Simple substitution, meaning of,

Simple substitutions,

[69]

[107]

Slides, slide-rules

for decrypting,

for encipherment,

used in transposition,

[13]

[61]

Specific key,

Statistics, some uses of,

“Step-up” and “step-down” letters,

[89]

“Straddling” devices,

[105]

Strips

used in decryptment of transpositions,

[15]

used for encipherment of polyalphabeticals,

used for decryptment of periodics,

[136]

Substitutes,

Substitution cipher, meaning of,

Substitution ciphers,

[212]

Symbols,

“Symmetry of position,”

[176]

Tableaux:

Vigenère,

[109]

Porta,

[118]

Beaufort,

[121]

used for decryptment of periodics,

[134]

formed in autokey decryptment,

[150]

high-frequency co-efficients,

[152]

imaginary, or formed in key-recovery,

Delastelle,

for finding alphabetical intervals,

[194]

for pair-encipherment,

[198]

“Taking off” (Transcription),

Terminals (see

statistics

)

Tetragram, meaning of,

Transformation device,

[102]

Transposition, meaning of,

Transposition ciphers,

Trial key,

“Trifid” substitution,

Trigram, meaning of,

Trigram encipherment,

[199]

Trigram method of solution:

applied to Beaufort,

[125]

applied to Gronsfeld,

[117]

applied to Porta,

[119]

applied to Vigenère,

[113]

with the use of a slide,

Trithème’s alphabet,

Unit,

United States Army Cipher Disk,