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CODES AND CYPHERS IN HISTORY
Codes and ciphers have been used since ancient times. The word CRYPTOGRAPHY,
meaning the science of codes, comes from the Greek words kryptos (secret)
and graphos (writing).
In 405 BC the Greek general LYSANDER OF SPARTA was sent a coded message
written on the inside of a servant's belt. When Lysander wound the belt
around a wooden baton the message was revealed. The message warned Lysander
that Persia was about to go to war against him. He immediately set sail
and defeated the Persians. The Greeks also invented a code which changed
letters into numbers. A is written as 11, B is 12, and so on. So WAR would
read 52 11 42. A form of this code was still being used two thousand years
later during the First World War.
The Roman ruler Julius Caesar (100 B.C. - 44 B.C.) used a very simple cipher
for secret communication. He substituted each letter of the alphabet with
a letter three positions further along, so that A became D, B became E
and so on. His famous phrase VENI, VIDI, VICI ("I came, I saw, I conquered")
would have read YHQL YLGL YLFL Later, any cipher that used this "displacement"
concept for the creation of a cipher alphabet, was referred to as a Caesar
cipher. Of all the substitution type ciphers, this Caesar cipher is the
simplest to solve, since there are only 25 possible combinations. Often
this type of cipher is implemented on a wheel device. A disk or wheel has
the alphabet printed on it and then a movable smaller disk or wheel with
the same alphabet printed on it is mounted forming an inner wheel. The
inner wheel then can be rotated so that any letter on one wheel can be
aligned with any letter on the other wheel.
For
example, if the inner wheel is rotated so that the letter M is placed under
the letter A on the outer wheel, the Caesar cipher will have a displacement
of 12. To encipher the letter P, locate it on the outer wheel and then
write down the corresponding letter from the inner wheel, which in this
case is B. The same can be accomplished by placing alphabets on two pieces
of paper and sliding them back and forth to create a displacement.
After
the fall of the Roman Empire codes were not used much until the sixteenth
century. Then Italian and French scholars began to make up very complicated
codes. The science of code-breaking - CRYPTANALYSIS - had begun In Elizabethan
England MARY QUEEN OF SCOTS sent coded messages to her supporters who where
plotting to murder Queen Elizabeth I. The messages were intercepted
by the head of Elizabeth's secret service, Sir Francis Walsingham. He deciphered
them and discovered the plot. Mary was executed for treason in 1587.
Modern Codes:
Morse
Code and Telegraphy:
The
invention of MORSE CODE in 1838 by the American, Samuel Morse, created
an entirely new way of sending messages quickly over long distances. Morse
is not actually a code but an ELECTRO-MAGNETIC TELEGRAPH SYSTEM which used
signals of 'dots' and 'dashes' to represent letters of the alphabet. If
a message in Morse was to be kept secret, it had to be put into code before
it was sent.
Look
at the Morse alphabet on the left. See how each letter is shown in dots
and dashes. Morse code was sent using a TAPPER.
Letter | Morse | Letter | Morse | Digit | Morse | ||
---|---|---|---|---|---|---|---|
A | .- | N | -. | 0 | ----- | ||
B | -... | O | --- | 1 | .---- | ||
C | -.-. | P | .--. | 2 | ..--- | ||
D | -.. | Q | --.- | 3 | ...-- | ||
E | . | R | .-. | 4 | ....- | ||
F | ..-. | S | ... | 5 | ..... | ||
G | --. | T | - | 6 | -.... | ||
H | .... | U | ..- | 7 | --... | ||
I | .. | V | ...- | 8 | ---.. | ||
J | .--- | W | .-- | 9 | ----. | ||
K | -.- | X | -..- | ||||
L | .-.. | Y | -.-- | ||||
M | -- | Z | --.. |
Letter | Morse | Punctuation Mark | Morse | |
---|---|---|---|---|
? | .-.- | Full-stop (period) | .-.-.- | |
? | .--.- | Comma | --..-- | |
? | .--.- | Colon | ---... | |
Ch | ---- | Question mark (query) | ..--.. | |
? | ..-.. | Apostrophe | .----. | |
? | --.-- | Hyphen | -....- | |
? | ---. | Fraction bar | -..-. | |
? | ..-- | Brackets (parentheses) | -.--.- | |
Quotation marks | .-..-. |
WIRELESS transmission means that messages are sent by RADIO WAVES through the air. To work in both directions it needs:
Some other famous cyphers:
-The
Vigenere Cipher
-The
Gronsfeld Cipher
-Simple
Substitution Cipher
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