Simple Substitution with Complexities
Concerning the numberless variations and complications which have
been applied to the simple substitution cipher, our discussion here
will have to be along general lines, with perhaps a brief mention of
some analytical principle. Decryptment, for the most part, involves
no principles other than those already discussed, and can only be
demonstrated on very long texts. All such ciphers, however, will
yield readily to the “probable word method,” and the student, in
considering each case, should not lose sight of the one method which
applies equally to all.
If the _probable word_ is a pattern word, so much the better; but
_every word carries a pattern in the normal frequencies of its
letters_. For instance, the word CIPHER, considered in relation to a
text of 100 letters, has, roughly, the frequency-pattern
3-7-2-5-12-6; or, considered in relation to a 200-letter text, a
pattern which is approximately double the first: 6-14-4-10-24-12.
A cryptogram supposed to contain this word may be prepared as
recommended in Chapter IX, with a frequency-figure written above
each letter. The frequency-pattern of the word CIPHER, based on
approximately the same amount of text, may then be written on a slip
of paper and passed along below the frequency-figures shown for
cryptogram-letters, in the hope of finding points at which the two
sets of figures are, to some extent, alike. Wherever such points can
be found, the suspected word can be assumed to be present there. So
long as the method remains that of simple substitution, any
substitutes which can be found in this way can have no other
originals than those first determined; thus, their substitution
throughout the cryptogram will serve to bring out other possibilities.
For the multiple-substitute cases, that is, those cases in which all
or part of the letters may have more than one substitute, the
frequencies of such letters as _I_, _H_, _E_, _R_, may be left blank
(or cut in half, dependent upon just what the cipher is), and only
the frequencies of _C_ and _P_, standing two positions apart, need
be considered. Particularly helpful, in this case, would be a
probable word such as CRYPTOGRAM, in which five infrequent letters
are standing at known distances apart. The frequency-pattern of this
word, based on 100, can be expressed roughly as _3 - 2 2 - - 2 - - 2_,
and the attempt made to find points in the cryptogram at which five
letters of somewhat these frequencies are standing at the given
intervals apart. The foregoing is based on the supposition that while
the encipherer, having several substitutes per letter, will be able
to conceal the true frequencies of his high-frequency letters, _there
is not much that he can do toward concealing his low frequencies_. He
can, of course, produce any frequencies that he likes by swamping his
text with nulls; and this, in the hands of a clever operator, can be
very effective, especially if the circumstances are such that he can
keep his method a secret. But for the average practical purpose, the
time consumed in the encipherment, and the increased length of the
cryptograms, are highly undesirable features, especially if it be
kept in mind that there are many other ciphers than simple
substitution. As to attack by analytical methods, the one device
which is more likely than any other to prove applicable in all cases
is the preparation of a digram count of exactly the kind we saw in
Fig. 68. Such a chart will afford the means for studying carefully
the _contacts_ of any given letter; just what its _variety_ seems to
be; whether or not this seems disproportionate to its apparent
frequency; whether or not it shows a tendency to touch letters of
lower frequency, or to be present in reversals; and so on.
Many of these ciphers, however, make use of two letters to represent
one. With these, it is the single-letter frequency count which is
best made on a chart. That is, the cryptogram is first marked off
into its pairs, and these pairs are counted in the same way as that
described for digrams. But digrams, in this case, will be represented
by four letters, and usually the number of different pairs is so
large that the examination of digrams will have to be done by
listing. For any cipher whatever in which the substitutes are
two-digit numbers, a frequency count taken in chart form is usually
far more convenient than one made by listing the numbers in advance.
With only the ten digits, the 100 cells can be made larger than the
676 cells needed for letters, and the chart still be small and
compact. The pairs of digits would be counted in exactly the same
way as so many digrams. With numbers, it is sometimes possible to
take the subsequent digram count, also, on a chart. Solution, in
many cases, involves pure guess-work. The decryptor, perhaps, has
begun his examination by testing his cryptogram for some variation
of the “Caesar” encipherment. He has counted the first hundred or
so of his letters, and has discovered that his frequency count is
not going to be that of an ordinary simple substitution; that is,
it is evidently not going to be one which he would be able to mark
off into sections of high, medium, and low frequencies (usually with
several letters missing), which would certainly be the case had each
plaintext letter been replaced always with a given substitute
throughout the cryptogram. Perhaps he has then marked his cryptogram
into pairs of numbers or letters, and finds that these, also, are
not likely to furnish the kind of frequency count which betrays
simple substitution or some other cipher with which he is familiar.
At this point, he is likely to pause and consider the source of the
cryptogram. Is this the work of an expert, or the work of an amateur?
Is it worthwhile to make up the statistics? Or shall I try for some
one of the novelties which I have met many times before?
One device which is particularly popular with amateurs is that of
assigning to each letter the numerical value which represents its
serial position in the normal (or reversed) alphabet, _A_ having the
value 1, _B_ the value 2, and so on, and afterward representing each
plaintext letter with two (or more) others which will express some
arithmetical process. For instance, the letter _C_ (value 3) might,
in some one of these systems, have the substitute _AB_ (1 plus 2),
or the substitute _DA_ (4 minus 1), or the substitute _YD_ (25 plus
4 equals 29; and 29 minus 26 equals 3); and so on to infinity.
Other simple devices, hardly worth calling ciphers, which have been
used in the columns of _The Cryptogram_ under the title “Simple
Substitution with Frills,” have included: (1) The use of false word
divisions. (2) The simple reversal of an otherwise unmanipulated
cryptogram. (3) The use of two given digrams, placed alternately at
the ends of words. (4) The use of a new cipher alphabet for each new
sentence. The first of these, of course, should have been suspected
after examination of the apparent terminal letters. The second,
theoretically, ought to be spotted if the method of solution includes
a close investigation of digrams. As to the third device, any two
digrams, used in the manner described, will attain impossible
percentages; our leading digram, _TH_, in normal text, remains fairly
close to three or four percent. It was the fourth device, however,
which caused the greatest consternation among the younger solvers;
in this case, the making of the frequency count will show what the
trouble is: It begins very well, with the expected resemblance to a
normal count, and suddenly begins to grow erratic.
Not every variation encountered in dealing with simple substitution
is employed with the deliberate intention of creating difficulties.
Those correspondents, for instance, who select some one letter, as
_X_, and place it after each word as a word-separator, do so because
they find it difficult to read their texts unless the word-divisions
are present. As to whether or not this device does actually create
difficulties: The person who is content to make use of simple
substitution as his means of secret communication, is not usually
inspired to employ more than one such letter. The length of an
English word being somewhat shorter than five letters, any single
letter placed religiously after each word will attain a frequency
(based on the new length) of not less than 18%, where the letter
_E_, at its very maximum, can rarely attain 15%. The decryptor,
taking his preliminary frequency count, quickly discovers this one
letter of enormous frequency. He might suspect German, or even
French, and look for other characteristics of those languages. But
having reason to believe that the language is English, he recognizes
this letter instantly for what it is; he first makes sure that it is
distributed throughout the cryptogram at an average interval of five
or six letters, then calmly circles it out and deals with a case of
word-divisions.
Figure 76
"Alphabet" for Encipherment of Numbers
"Plaintext" .. 1 2 3 4 5 6 7 8 9 0
"CIPHER" ... A B C D E F G H I J
Text ready for encipherment:
WE HAVE WCBEW BALES.
Considering something of a more practical nature, there is another
very common device, used with every conceivable kind of cipher, which
is not in the least intended for the purpose of creating difficulties,
yet invariably does in short cryptograms. The ordinary practice, when
dealing with numbers, necessary punctuation marks, and so on, is to
write these out in words: _three hundred twenty five_; _quote_;
_dollars_. But where a given correspondence is likely to involve a
great many of these, so that the ordinary practice is very wasteful,
the encipherer is nearly always provided with a little “cipher
alphabet” of the general kind indicated in Fig. 76, in which the ten
digits, any desired punctuation marks, and any other needed symbols
($, %, @) have each a single substitute. In the “alphabet” of the
figure, the number 325 will be enciphered _CBE_. But if this
enciphered group _CBE_ is always to be cleanly distinguishable from
the rest of the text, a means must be found for making this
distinction, and this is usually done by reserving some one letter
to act solely as an _indicator_ and never using this letter for any
other purpose. This indicator-letter, as _W_, may then be placed at
the beginning and end of the enciphered group _CBE_, and the
resulting group, _WCBEW_, may be placed in the plaintext message,
ready to receive whatever kind of encipherment is given to the rest
of the letters. These groups, used in short cryptograms, can give
about the same amount of trouble as would so many nulls. But where
cryptograms are longer, with a great many such groups, the decryptor
invariably spots them by means of the recurrent indicator. Sometimes
one letter is used, and sometimes two (_W_. . ._W_, or _K_. . ._W_);
but in either case, the indicator always appears as a pair of
correlatives, and wherever the first of the pair is found, its
companion is never far away. Some provision must, of course, be made
for replacing the indicator letter in the plaintext alphabet. In
English, we ordinarily select _J_ for any such omission; this is a
letter which is rarely used, and, on those scattered occasions when
it does occur, it can be replaced with _I_. Among the Latins, it is
commoner to make use of _K_ and _W_; these two letters are not used
at all in their native languages, and can be replaced, respectively,
with _Q_ and _VV_. It is also possible to omit _X_, replacing it with
_KS_, or _V_, replacing it with _U_. The fact that it is possible to
shorten the message alphabet without appreciably impairing the
clearness of its messages has given rise to what is probably the most
practical of the simple substitution variations: two or three
letters, as _J_, _K_, _V_, are omitted from the plaintext alphabet,
while the cipher alphabet retains its full 26, and in this way some
extra substitutes are provided which can be given to the more
frequent letters. It is possible to dispense with as many as five
letters, replacing _J_, _K_, _X_, _V_, _W_ with _I_, _Q_, _QS_, _U_,
_UU_, and assign the extra substitutes to _E_, _T_, _A_, _O_, _N_.
Fig. 77 illustrates an alphabet of this kind. Here, the letters _I J_
are to have the same substitute, and the letters _K Q_ are to have
the same substitute. This releases two extra substitutes which may
be given to _E_ and _T_.
Figure 77
j q
Plaintext: a b c d e f g h i k l m n o p r s t u v w x y z E T
CIPHER: C U L P E R Z Y X W V T S Q O N M K J I H G F D B A
Encipherment:
w e m u s t h a v e b e t t e r c o v e r a g e ...
H E T J M K Y C I B U E A K B N L Q I E N C Z B ...
The foregoing is one of those cases in which the decryptor can learn
a great deal by taking his frequency count in the form of a digram
chart. And he knows, of course, that his cryptogram contains some
two letters whose combined frequencies will reproduce the frequency
of _E_, or of _T_.
In Fig. 78, we have a “checkerboard” which, primarily, is intended as
a _transformation device_; that is, a means for replacing single
letters with syllables, and, consequently, for replacing five-letter
incoherent groups with ten-letter pronounceable groups; under the
European agreement, the price of transmission is the same for both,
and the pronounceable groups are less likely to result in
transmission errors. The alphabet is first reduced to 25 letters (in
this case by the omission of _X_), and is written into a 5 x 5 square.
The five vowels, written at one side, will then serve to designate
the five rows, while five other letters, written across the top, will
designate columns. Any letter found inside the square may thus be
pointed out by naming the two letters which will indicate its column
and row. In the given example, _A_ can be replaced with _EN_ or _NE_;
_T_ with _UL_ or _LU_, and so on.
Figure 78
L N R S T
b a t t a l i o n
A C U L P E ER NE UL LU NE AR RI OR NO
E R A B D F
I G H I J K
O M N O Q S Regrouped:
U T V W Y Z
ERNEULLUNE ARRIORNO.
The fact that two interchangeable substitutes have been provided for
each letter of the alphabet has led many persons to use this device,
absolutely without modifications, as a simple substitution key. Yet
it must be plain that any decryptor, taking his preliminary frequency
count, will discover, before going very far, that this count is being
made on only ten different letters, and thus can represent only one
possible kind of encipherment. A frequency count taken on the pairs,
with no distinction made between a given digram and its reversal,
will afford the necessary proof; after that, the average decryptor
will usually replace the pairs with single letters (or numbers), just
as he would in dealing with printers’ symbols, or other inconvenient
characters. The checkerboards which are actually intended for
encipherment purposes ordinarily use digits for pointing out columns
and rows. Where the digits at the side are the same as those across
the top, it becomes necessary to observe an order, as column-row, or
row-column, and this, using only five digits, is ordinary simple
substitution, in which every letter has one substitute. But if the
five digits at the side are different from the five written across
the top, then the order is immaterial, and any number may be
interchangeable with its reversal; that is, 17 or 71 can represent
the same letter.
This encipherment might not be spotted so promptly as the case in
which only ten letters are present out of a possible 26. But if the
count is made on a chart, as recommended at the beginning of the
chapter, it is very readily detectible that there are two separate
groups of digits, _neither one of which has ever formed any
combination within itself_, every number in the cryptogram being
composed of one digit from each group. Thus we see plainly the trail
which is left by co-ordinates.
Figure 79
The KEY-PHRASE Cipher
(a)
Plaintext: a b c d e f g h i j k l m n o p q r s t u v w x y z
CIPHER: O N E W H O H A S P A S S E D O N I S A M O N G U S
(b)
CIPHER....... O M S S
May represent: A U I I Full
F L L Fuss
P M M Fuzz
V S S Pull
Z Z Puss
Checkerboards, of course, can be used to better advantage. But,
before leaving the simple for the complex, we must not overlook the
celebrated _key-phrase cipher_, which discards the idea of multiple
substitutes in favor of multiple originals! This cipher, shown in
Fig. 79, is said to have been used for serious purposes. Its only
difference from the ordinary simple substitution lies in the nature
of the cipher alphabet, which must be a plaintext sentence, or phrase,
containing the necessary 26 letters. The mysterious pronouncement,
“One who has passed on is among us,” is the earliest example of which
the writer has any recollection; those of later years have been
largely proverbs, or other familiar sayings: “Journeys end in lovers’
meeting”; “Prosperity is just around the C.” As any cryptogram-letter
may have five or six different originals, it is readily understood
why the cryptograms of the key-phrase cipher are seldom seen without
their word-divisions; yet, curiously enough, their translations are
almost never ambiguous.
As to their decryptment, the student who cares to try the appended
example will find that it is hardly more difficult than one of the
simpler “aristocrats.” The method is about the same for both, keeping
in mind that the frequency shown by any cryptogram-letter is either
the frequency belonging to one letter or the exact sum of the
frequencies belonging to several. Here, however, the reconstruction
of the key simultaneously with the identification of substitutes is a
very important adjunct to solving; the cipher-alphabet, being pure
plaintext, can often be built up long in advance of solution. It
might be added that this cipher, with or without word-divisions, is
readily distinguished from all others by the make-up of its frequency
count, which, as a rule, consists chiefly of the high-frequency
letters in unusual numbers.
Passing now to the more difficult cases, we will glance at a few of
those ciphers which are truly multisubstitutional; that is, which
provide multiple substitutes for all or most of the plaintext letters.
This is usually accomplished by the use of two-digit numbers, of which
one hundred are possible: 01-02-03. . . . . .98-99-00. These one
hundred numbers may be assigned as substitutes to the twenty-six
letters, in proportions roughly approximate to their normal
frequencies, as suggested in Fig. 80; or most of them may be so
assigned, and the rest reserved as substitutes for digits,
punctuation, and so on. For security, however, they must never be
assigned in regular order, as in the figure, or even by any
methodical process, but absolutely in incoherent order. Thus, while
the form indicated in Fig. 80 will be convenient enough for
encipherment purposes, it is much less so for decipherment, and
ordinarily there will be two separate tables, the second of these
making it more convenient to find numbers. This _deciphering key_
can be prepared as a list, running in numerical order; but a much
more usual and convenient method is that of preparing it in the form
of a chart; that is, the ten digits are written across the top and
along one side of a 10 x 10 square, exactly as if making ready to
take a number-count, and the letters, or other characters, are then
distributed in the 100 cells so that the correct digits will serve as
co-ordinates for pointing them out. Such a key is changeable, but not
readily communicated and remembered without written documents; and to
overcome this very serious defect, many mnemonic devices have been
conceived, of which the following is perhaps the most practical:
Simply treat the one hundred numbers as if they were a plaintext
message, and encipher the series by any one of the irregular
transposition processes.
Figure 80
A 11, 12, 13, 14
B 15
C 16, 17
D 18, 19
E 20, 21, 22, 23, 24
(Etc.)
The two commonest of the checkerboard keys are shown in Fig. 81. When
digits are used, as in (a), an order must be observed in reading the
two co-ordinates. The letter _L_, for instance, may have any one of
the substitutes 13, 18, 63, or 68, but may not also have their
reversals, since these, using the same order, row-column, would all
be substitutes for _G_. Using letters, however, it is possible to
have two entirely different series at top and side, as in (b); in
this case, no order need be observed, and the letter _L_ may have any
one of eight substitutes: _KE_, _KF_, _LE_, _LF_, _EK_, _FK_, _EL_,
or _FL_. By including the still unused letters _U V W X Y Z_, it can
be arranged to provide yet more substitutes for some of the letters.
For either of these cases, the external numbers or letters (preferably
in mixed order), could constitute a semi-fixed key — that is, one not
changed every day — while the mixed alphabet of the square could be
changed as often as desired. Innumerable other keys of this type are
found. For the most part, they are based on rectangles of 35, 36, or
40 cells, the extra cells being used for digits, or other desired
symbols, and especially for extra appearances of the more frequent
letters.
Figure 81
(a) (b)
1 2 3 4 5 A C E G I
6 7 8 9 0 B D F H J
1-6 C U L P E K-L C U L P E
2-7 R A B D F M-N R A B D F
3-8 G H I J K O-P G H I J K
4-9 M N O Q S Q-R M N O Q S
5-0 T V W Y Z S-T T V W Y Z
One such key, the Grandpré cipher shown in Fig. 82, uses 100 cells.
The filling of the square with ten ten-letter words provides letters
in somewhat the normal frequency proportions, and an eleventh
ten-letter word, composed of the ten initials, serves as a sort of
mnemonic device for stringing the first ten together. The words, of
course, must be chosen in such a way as to include all 26 of the
letters.
General Sacco, dealing with fractional substitutions (Chapter XXII),
shows the same idea in a checkerboard which he describes as
“frequential.” This square is simply filled with letters, used in
proportions roughly approximating their normal frequencies; for ready
finding, all repetitions of a letter are placed close together, but
filled in on diagonals, which, to some extent, will prevent their
being represented by consecutive numbers.
Figure 82
The GRANDPRÉ Cipher
1 2 3 4 5 6 7 8 9 0
1 E Q U A N I M I T Y
2 X Y L O P H O N E S
3 H A L F O P E N E D
4 U N B L O C K I N G
5 M O V A B I L I T Y
6 A D J U R A T I O N
7 T H E O R I Z I N G
8 I G N O R A N T L Y
9 O W N E R S H I P S
0 N O V I T I A T E S
In Fig. 83, we have the checkerboard again, with a modification. If
the key used is exactly the one of the figure, those letters which
are standing on the first three rows may have twelve substitutes each,
and those which are standing on the fourth row may have eight. In all
of these cases, the substitute for any letter is a pair. But the final
row, including here the letters _V W X Y Z_, is not enciphered with a
pair of co-ordinates; each letter may represent itself, or each may
represent the one on its left or right, but in any case, the
substitute is a _single letter_. Thus we have cryptograms in which
most of the letters are represented by pairs, but a few are not. Such
words as _ever_, _you_, _with_, _when_, _by_, _have_, and so on, will
occasionally occur; or, if not, then the encipherer may insert a few
nulls at strategic points. Thus, the decryptor, taking his count
purely on pairs, is expected to take some of them correctly and
“straddle” the rest. Such a device is described by Givierge, also the
following similar device. The cipher alphabet consists only of
two-digit numbers, but includes no number coming from the 40’s. With
all of the 40’s omitted, a sequence 44 becomes impossible; and the
encipherer, having first prepared his cryptogram, looks it over, and,
here and there, inserts a digit 4 beside another digit 4, producing
the impossible sequence 44. The decipherer, wherever he sees this,
need merely erase one of the 4’s, and since the digits, in Morse,
have their own distinctive symbols, there is no great danger of
errors in transmission which the decipherer will be unable to
straighten out; but the decryptor, as before, is expected to
“straddle.” Concerning decryptment, in all of these cases, there is
little that we can say here except that, given sufficient material,
these ciphers can all be decrypted with comparatively little trouble.*
The “straddling” devices, perhaps, would represent the most difficult
case, presuming that the decryptor has no probable words and none of
the information which comes through espionage or from that even more
fertile source, the carelessness of the encipherer. In dealing with
one of these, the decryptor, who normally expects a certain amount
of uniformity in the frequency counts made from different portions
of a same cryptogram, is likely to find that his count is showing
altogether new substitutes, or the same substitutes with altogether
new frequencies. He suspects, then, that he may be “straddling”
between two pairs, and tries making his count _in sections_ until he
finally discovers what letters (or digit) are causing the trouble.
*For a clear and detailed exposition of the decryptment method
ordinarily used in multiple-substitute cases, see _Secret and Urgent_
(Bobbs-Merrill), page 64 et seq. For dictionary cipher and simple codes,
see _The Solution of Codes and Ciphers_, by Louis C. S. Mansfield
(Maclehose), page 56 et seq., or _Cryptography_ (Langie-Macbeth;
Dutton), page 88 et seq.
Figure 83
K L M N O
F G H I J
A-E-S A B C D E b a X t t a l i o n
B-P-T F G H I K AG EF Y NR DI SK KU TI CN HQ
C-Q-U L M N O P =
D-R Q R S T U
V W X Y Z
The use of co-ordinates, in those cases where row and column are
interchangeable as to order, shows up very plainly when the
pair-count has been made on a chart; as previously mentioned for a
case of digits, the letters will divide automatically into two groups,
neither of which ever forms any combination within itself. With the
other case, where an order must be observed, there are not so many
substitutes per letter. But in either case, it is possible to _pair
the letters_ which belong together. Here, for instance, are the
letters _E_ and _F_. The frequent combinations of both _E_ and _F_
are always formed with the same letters; and both have avoided the
same letters; _these two must have been paired_. Their combinations
with _G_ and _H_ are much more frequent than their combinations with
_I_ and _J_; thus _G_ and _H_ must have been paired, and _I_ and _J_
must have been paired. This combination _EG_ (and its equivalents),
has been frequently followed by this other combination (and its
equivalents) and so on. When a great many pairs can be considered
equivalent to one another, it is possible to begin setting up the
checkerboard. Some such devices, of course, are safer than others.
But the mere fact that they double the lengths of the cryptograms
renders them unfit for any purpose where speed is a requirement; nor
can the added time and expense of transmission be tolerated for any
purpose whatever unless there is some very definite gain in secrecy.
Figure 84
An Example of BOOK CIPHER
4-1 1-5 3-16 4-11 1-3 1-6 2-2 6-21 1-4 3-2 4-25 4-2
3-3 l-l 2-12 5-22 4-10 6-7 6-2 5-6 5-7 2-7 1-2 1-8
6-1 3-7 5-4 3-6.
(Key "volume": 23d Psalm).
One great objection to any device offering optional substitutes is
that the encipherer himself seems unable to take full advantage of
his system. Even having at his disposal five different substitutes
for _E_, he falls into the habit of using one of these in preference
to the other four; or, determined to avoid this, he uses them
meticulously according to rotation, so that when a frequency chart is
prepared from his cryptograms, this chart, which is, after all, a
_graph_, will show the five uniform frequencies sticking out like a
sore thumb. Even _book cipher_, notably secure, however unwieldy in
use, has been decrypted because of the encipherer’s very human
tendency to use a substitute more than once rather than search for a
new one among the hundreds at his disposal.
In book cipher, any agreed book, or other written or printed document,
will serve as a _key-volume_, so long as it is one that is sure to be
at hand when wanted. Words, or letters, can then be represented by a
series of numbers usually indicating: page, (column), line, serial
position. One letter or one word may thus have a substitute such as
20-1-4-32. An example is provided in Fig. 84, which the interested
student may puzzle out for himself. The particular key-volume was
issued in 1848, but we think this should cause no trouble. When the
key-volume selected happens to be the ordinary dictionary, identically
the same cipher becomes known as _dictionary cipher_, which is, to all
intents and purposes, a very insecure form of _code_. Perhaps the two
names together, book cipher and dictionary cipher, might be said to
represent the maximum and minimum degree of safety found in the code
family.
We leave undiscussed the subject of those alphabets which are based
on phonetics, with digraphs _TH_, _SH_, _CH_, having their individual
symbols, and each vowel capable of having several. The student who
desires to prepare one may find the necessary suggestions in any
shorthand manual; his substitutes can be two-digit numbers, and his
encipherment may be any one of those intended for the normal alphabet.
Having made mention of several processes which, to the younger student,
may present frightening possibilities, we hasten to add that the four
appended examples are all of a type which he should be able to solve
without a great deal of difficulty.
100. By PICCOLA. (Key-Phrase Cipher - intercepted by a "Royalist" spy).
N H H K O H W A E H M A U I H U U H S T U S A S T U N H U
M H N I W A H T. N H H H S A D T H H I A I I E I A M H K M
U W A H O L W N W H T M A M D S T H A J T E S U T O T K
N W I E W A O O. O U H K M W A H M N U I H U U H S T N W T O I K
H K M W A H A H O A N W T O I K A W O.
101. By PICCOLA. (Probable words: CIPHER, SUBSTITUTION, ALPHABET, etc).
D K I U O C Z P V C L U Z I Q U W Y V B V I N C D U U L C U K U Z I I
U O C Z P V C L U Z P Y N U S Q S C Z I U L Q T U K H I C Z I K L U Z
P Y N N Y J Q Y L U P L U Z I Q J S C U L U S U E Y G U Z I Q I U T Q
N U F S U Z F L U I C V F Q S W Q I I S U Y S U G S Q N B L U G U O V
V Y F S Q Y I H I Y I K O H K U V P T Y K Q I J U Y V P P C E S Y U O
F Q S U L C Z N Y Z F K E S Y Z I U Z I R Q V V C.
102. By PICCOLA. (Probable words: COLLECTION, GALLERIES, FIGURINE, etc).
Y C G U T H M P Y B X S K R M G X U F P C M I B C J G R M K X L X S Z
N Q V V U N I X Q S Q E E X Z H M X S R L E Q M L C V U D Y C G R N Q
S E X J U S K X C V X S E Q M T C I X Q S K Y C I I Y R K C S C Z M C
L I Q V U S E M Q T K Y R T Q M Z C S Z C V V U M X R L F C L L U R S
M U N R S I V B X S C N U M K C X S W H C M I R M D Y C L L X S N U J
X L C P P R C M U J D T C B O R X S K Y X L E U V V Q F L N Q V V R N
I X Q S S Q F X X X.
103. By EFSEE. (Probable words: PEOPLE, PERSON, CIRCUMSTANCES, etc).
B E C O M I C I Q U E X P A Y O T I A N S I Z I P I A N D O A B U M Y
O R E A N U S Q U I M O N I P M A M A M I F O X E G A O K A Z U K I S
G O V I X A W A Z A I T H I N A I L M O S U I S H E A T R U A L E M O
F A T I C A G I D O Y E M B E Y O L E N A C O S E K E E L S O G I Z A
C O O L S I D I O R Q U A Z O W A G E S D I B U S I V I P U A Z A M E
S I D A R T A C O O Y A P E S L I A R S E W O A L O N I K O L O M B A
R I L A Z A L O W I A V U M A K A T L O F I C I N A I M I L N A Q U I
M O N I P S A W O G A P A V I H I S U E C A N O S M O L E T A M E K O
W A I V S I A R T E Z E I R S I L A Z E G A S A M I V E E P.