CIPHERS AND CRYPTOGRAMS
SUCCESSFUL SYSTEMS OF SECRET WRITING
FROM the earliest times secret writing has been considered no less an
art than a necessity. Innumerable have been the systems invented and the
means employed to insure the secrecy of messages and instructions. Yet
in the passage of time by far the greater number of these methods of
cipher has become obsolete and practically useless, failing in most
cases to comply with the three great necessities which Bacon declared to
be indispensable to all ciphers and cryptograms: (1) Easy of reading and
writing; (2) difficult of solution; and (3) void of suspicion.
Ciphers may be generally divided into two branches--code ciphers and
letter ciphers. The first of these terms refers to systems so arranged
that one group of characters represents several words or sentences,
whilst the other term designates those cryptograms where each letter in
every word has its corresponding symbol.
As letter ciphers are the more usual, and certainly the handier of the
two classes, examples are given of some systems which have been
successfully used at different times and for different purposes.
The simplest of all methods, and, for that matter, the easiest to be
detected, consists in having an arbitrary list of numbers, one of which
shall represent each letter in the alphabet--_e.g._, A appears as 4, B
as 8, C as 12, &c.
This plan can be varied by substituting letters for the numbers, and
having each letter of the alphabet represented by another
letter--_e.g._, A being substituted by G, B by L, C by Q, and so on; but
the disadvantages attending these very simple ciphers are so great that
for a message of any real importance the system is useless.
In the same way the expedient of reversing the alphabet and making A
represented by Z, B by Y, C by X, is too simple and generally known to
require further description.
One of the easiest and earliest ciphers is shown in Fig. 1. This is
written in the following manner: The “bounding” lines in which the
desired letters are contained are drawn and the position of the letter
in them indicated by a dot. Taking, for example, Fig. 1, A would be one
dot, B two, and C three dots inscribed inside the two lines forming the
angle. Thus the word CIPHER would be written
───┐ ┌───┐ ───┐ ───┐ ┌───┐
•••│ •••│ │ • │ • •│ • •│ │•••│
───┘ ───┘ .
At this point it might be remarked that in all the examples here given
the letters are arranged in their simplest order--that of alphabetical
sequence; whereas, for practical purposes, they can be arranged in any
form desired, the more complicated the better. To illustrate this Fig. 2
shows another arrangement of the letters, by using which the same word
would appear
┌───┐ ┌─── ───┐ ┌───┐
│ • │ │ • │• • • │ │ • │•••│
└─── └─── ───┘ └─── └───┘.
A B C | J K L | S T U
-------+-------+-------
D E F | M N O | V W X
-------+-------+-------
G H I | P Q R | Y Z
FIG. 1.--One of the earliest ciphers.
d j v | a o w | e p u
-------+-------+-------
h l s | b m r | i y
-------+-------+-------
g k t | c q x | f n z
FIG. 2.--Another arrangement of cipher shown in Fig. 1.
An example of another simple cipher created merely by the transposition
of letters is shown in Fig. 3, which can be read by taking the first
letter of the first line, the last letter of the last line, the last
letter of the first line, and the first letter of the last, then the
last letter of the first line, the penultimate letter of the last, and
so on. When the letters in Fig. 3 are properly transposed they will be
found to read “A very simple cipher.”
a y p e i e
c e p
h r i
r m l s v
FIG. 3.--Transposition of letters cipher.
Lord Bacon invented a cipher composed of two letters only, which,
although confusing to the uninitiated, is somewhat too cumbersome for
any general use. Supposing the two letters decided upon to be A and B,
they are grouped into series of five and employed in the following
manner: The first letter in the alphabet, A, is represented by AAAAA, B
becomes AAAAB, C appears as AAABA, D as AABAA. Using this combination,
the same word “cipher” would be written AAABA, BBAAA, BBBBB, AABBA,
ABAAA, BBBAB.
Amongst the easy ciphers must be mentioned that shown in Fig. 4, which
is used thus: In the center block of small type you find the letters of
the word you wish to write in cipher. Suppose it to be TO-MORROW. Now in
the vertical column at the side you find that the letter on a line with
“t” is A, whilst the letter at the top of the vertical column is G.
Therefore the cipher letters for “t” are AG. The next letter, “o,” is on
a line with B and under E, so the cipher letters are BE. In a similar
way “m” becomes CD, and, proceeding with the remaining letters in the
same fashion, we obtain the whole word written in cipher thus: AG, BE,
CD, BE, BF, BF, BE, CG.
+---+---+---+---+---+---+---+---+---+
| | A | B | C | D | E | F | G | H |
+---+---+---+---+---+---+---+---+---+
| A | a | d | g | k | n | q | t | x |
| B | b | e | h | l | o | r |uv | y |
| C | c | f |ij | m | p | s | w | z |
+---+---+---+---+---+---+---+---+---+
FIG. 4.--The “two-letter” cipher.
+---+---+---+---+---+
| 1 | 2 | 3 | 4 | 5 |
+---+---+---+---+---+---+
| 1 | a | b | c | d | e |
+---+---+---+---+---+---+
| 2 | f | g | h | i | j |
+---+---+---+---+---+---+
| 3 | k | l | m | n | o |
+---+---+---+---+---+---+
| 4 | p | q | r | s | t |
+---+---+---+---+---+---+
| 5 |uv | w | x | y | z |
+---+---+---+---+---+---+
FIG. 5.--The Nihilist code.
RUSSIAN NIHILIST CODE
An adaptation of the last-mentioned system is shown in Fig. 5, where the
letters at the side and top are replaced by numerals. This method is
very much in use amongst the Russian Nihilists, who would therefore
write the sentence “Plot discovered” as follows: 41, 32, 35, 45; 14, 24,
44, 13, 35, 51, 15, 43, 15, 14.
This, again, can be very much complicated by multiplying each number by
the position held by the letter in the word. Thus in the sentence just
put into cipher, P is the first letter in the word “plot,” L is the
second, O the third, T the fourth, whilst in the next word D is the
first, I the second, &c. You therefore multiply the ciphers in the first
word by 1, 2, 3, 4 respectively, and deal similarly with those of the
second word. The sentence thus treated would appear--41, 64, 105, 180;
14, 48, 132, 52, 175, 306, 105, 344, 135, 140.
To read this the system must be reversed, and each number divided by its
position in the word.
[Illustration: FIG. 6.--A musical cipher.]
A useful form of musical cipher is shown in Fig. 6, which explains
itself. In using this system it is usual to separate the different words
by dividing the notes into bars, as can be seen from a glance at Fig. 7.
Here it will be noticed that only crotchets and minims are used for
ciphers, whilst the other notes introduced have no significance, only
serving the purpose of confusing whoever has sufficient curiosity to pry
into the message. Therefore, discordant as the passage may sound to the
wrong person, it probably makes very sweet music to whoever has ears and
eyes to understand its meaning.
[Illustration: FIG. 7.--A musical appointment.]
Before proceeding to more complicated ciphers, that known as the
fractional may be mentioned. This is a very simple method, and easily
learned. The letters of the alphabet are divided into groups of five as
shown in Fig. 8, each group being marked successively up to five, and
each letter in the group treated in the same way. The numerator is used
to designate the group to which the letter belongs, whilst the
denominator shows the individual letter in that group.
1 2 3 4 5
--------- --------- --------- --------- -----------
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
1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
FIG. 8.--The fractional cipher.
Adopting this method the word CIPHER therefore appears as in Fig. 9. As
numerals above 5 do not appear in this cipher any more than does the
figure 0, they can be added at will to complicate the appearance of the
cryptogram, as shown in Fig. 10, where the same word is shown with the
addition of meaningless numerals.
1 2 4 2 1 4
- - - - - -
3 4 1 3 5 3
FIG. 9.--The word “cipher.”
10 29 43 28 10 47
-- -- -- -- -- --
38 40 16 39 56 39
FIG. 10.--Complicated fractional cipher.
THE SPHINX
Now to turn to more scientifically constructed ciphers, such as have
been employed by various Governments in correspondence with their
ambassadors and secret servants.
The Sphinx Cipher, shown in Fig. 11, is based upon a key-word of six or
seven letters, previously arranged by the parties concerned A
key-alphabet is written in full at the top of the plan, and against each
letter of the key-word a complete alphabet is written as shown in the
figure.
+---+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |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|
+---+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| B |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|a|
+---+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| A |c|d|e|f|g|h|i|j|k|l|m|n|o|p|q|r|s|t|u|v|w|x|y|z|a|b|
+---+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| L |d|e|f|g|h|i|j|k|l|m|n|o|p|q|r|s|t|u|v|w|x|y|z|a|b|c|
+---+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| F |e|f|g|h|i|j|k|l|m|n|o|p|q|r|s|t|u|v|w|x|y|z|a|b|c|d|
+---+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| O |f|g|h|i|j|k|l|m|n|o|p|q|r|s|t|u|v|w|x|y|z|a|b|c|d|e|
+---+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| U |g|h|i|j|k|l|m|n|o|p|q|r|s|t|u|v|w|x|y|z|a|b|c|d|e|f|
+---+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| R |h|i|j|k|l|m|n|o|p|q|r|s|t|u|v|w|x|y|z|a|b|c|d|e|f|g|
+---+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
FIG. 11.--A Government cipher, called the “Sphinx.”
Suppose that the key-word chosen is BALFOUR, and that the message to be
sent is WAR DECLARED LEAVE NOW, the key-word is then applied to the
message thus:--
WAR DECLARED LEAVE NOW.
BAL FOURBALF OURBA LFO.
You then find in the top row the first letter of your message, which is
W, and you see that the letter on a line with B and under W is X, which
will be the first letter of your cipher. You then find A above and A by
the side, which will give you C. You then find R above, and in the L
horizontal column is its equivalent U. Proceeding thus with your message
you arrive at the cipher, which reads: XCU HJISBTHH QKHWG QSB.
To read this it is only necessary to write the key-word under the cipher
and reverse the proceeding.
An ingenious cipher, used by the War Office of a well-known Continental
Power, is partially shown in Fig. 12.
On two adjacent sides of a square entire alphabets are written,
commencing at any letter (in the figure they begin at K in one and S in
the other). Against each letter of the perpendicular alphabet the
entire twenty-six letters are written horizontally, beginning with A and
continuing in order. Leaving the first of these horizontal alphabets
simple, against the remaining twenty-five, small alphabets are written
as you will see in the figure, which shows the plain alphabets and five
letters so treated.
+---+--+--+--+--+--+--+--+--+--+--+--+--+--+
| |K |L |M |N |O |P |Q |R |S |T |U |V |W |
+---+--+--+--+--+--+--+--+--+--+--+--+--+--+
| S |A |B |C |D |E |F |G |H |I |J |K |L |M |
+---+--+--+--+--+--+--+--+--+--+--+--+--+--+
| T |Aa|Ba|Ca|Da|Ea|Fa|Ga|Ha|Ia|Ja|Ka|La|Ma|
+---+--+--+--+--+--+--+--+--+--+--+--+--+--+
| U |Ab|Bb|Cb|Db|Eb|Fb|Gb|Hb|Ib|Jb|Kb|Lb|Mb|
+---+--+--+--+--+--+--+--+--+--+--+--+--+--+
| V |Ac|Bc|Cc|Dc|Ec|Fc|Gc|Hc|Ic|Jc|Kc|Lc|Mc|
+---+--+--+--+--+--+--+--+--+--+--+--+--+--+
| W |Ad|Bd|Cd|Dd|Ed|Fd|Gd|Hd|Id|Jd|Kd|Ld|Md|
+---+--+--+--+--+--+--+--+--+--+--+--+--+--+
| X |Ae|Be|Ce|De|Ee|Fe|Ge|He|Ie|Je|Ke|Le|Me|
+---+--+--+--+--+--+--+--+--+--+--+--+--+--+
+---+--+--+--+--+--+--+--+--+--+--+--+--+--+
| |X |Y |Z |A |B |C |D |E |F |G |H |I |J |
+---+--+--+--+--+--+--+--+--+--+--+--+--+--+
| S |N |O |P |Q |R |S |T |U |V |W |X |Y |Z |
+---+--+--+--+--+--+--+--+--+--+--+--+--+--+
| T |Na|Oa|Pa|Qa|Ra|Sa|Ta|Ua|Va|Wa|Xa|Ya|Za|
+---+--+--+--+--+--+--+--+--+--+--+--+--+--+
| U |Nb|Ob|Pb|Qb|Rb|Sb|Tb|Ub|Vb|Wb|Xb|Yb|Zb|
+---+--+--+--+--+--+--+--+--+--+--+--+--+--+
| V |Nc|Oc|Pc|Qc|Rc|Sc|Tc|Uc|Vc|Wc|Xc|Yc|Zc|
+---+--+--+--+--+--+--+--+--+--+--+--+--+--+
| W |Nd|Od|Pd|Qd|Rd|Sd|Td|Ud|Vd|Wd|Xd|Yd|Zd|
+---+--+--+--+--+--+--+--+--+--+--+--+--+--+
| X |Ne|Oe|Pe|Qe|Re|Se|Te|Ue|Ve|We|Xe|Ye|Ze|
+---+--+--+--+--+--+--+--+--+--+--+--+--+--+
FIG. 12.--Another Government cipher--still in use.
The cipher is used in this way. The letters in each word of the message
are divided into couples. These couples are found in the doubled
alphabets in the center of the cipher scheme, and the key letters at the
side and top show the actual cipher equivalent.
Suppose it is desired to put into this cipher the words CABLE CODE.
Dividing the letters into couples CA, BL, E. CO, DE are obtained.
Finding the combination CA it is simple to ascertain that the index
letters are TM, which is therefore the cipher. BL is EL, whilst the
remaining letter E from the top alphabet is found to be SO. Treating the
word CODE in the same way the ciphers prove to be HM, XN, and therefore
the message is transmitted thus: TMELSO HMXN.
So far an idea has been given of the systems of cipher from the simplest
methods to the most complicated of political cryptograms. Although the
actual details are necessarily hidden, it may be assumed as a positive
fact that the most secret political ciphers now in use by civilized
Governments are but adaptations of one or other of the methods
described.