This document discusses various types of codes and ciphers used throughout history for secure communication. It explains that codes operate at the word or phrase level by assigning whole words or phrases to symbols, while ciphers operate at the letter level by substituting letters for other letters, numbers, or symbols. Examples of codes and ciphers discussed include the Caesar cipher, Morse code, Enigma machines, and the code used by Mary Queen of Scots. Frequency analysis is introduced as an effective method for cracking ciphers by analyzing which symbols appear most frequently and mapping them to the most common letters in a language.

2. A code is a rule for converting a piece of information (for example, a
letter, word, phrase, or gesture) into another form or representation
(one sign into another sign), not necessarily of the same type.
Encoding is the process by which information from a source is
converted into symbols to be communicated. Decoding is the
reverse process, converting these code symbols back into
information understandable by a receiver.
One reason for coding is to enable communication in places where
ordinary spoken or written language is difficult or impossible.

3. The simplest form of a code is the "jargon code", in which
a particular arbitrary phrase is used as code.Jargon codes
have been used for a long time, most significantly in
World War II, when they were used to send commands
over broadcast radio to resistance fighters
“BOXER SEVEN SEEK TIGER5 AT
RED CORAL” This uses "code words"
to report that a friendly military force
code named BOXER SEVEN is now
hunting an enemy force code named
“The nightingale sings at dawn” --
TIGER5 at a location codenamed RED
corresponds to a particular
CORAL. This particular code is weak
predefined message and the actual
meaning of this might be: “The in that the "SEEK" and "AT" words
supply drop will take place at 1hrs provide information to a code breaker
tomorrow”. on the structure of the message. In
practice, military codes are often
defined as "code numbers" rather than
code words, using a codebook that
provides a dictionary of code numbers
and their equivalent words.

4.  Caesar cipher used by Julius Caesar to communicate with his
army. Caesar is considered to be one of the first persons to have
ever employed encryption for the sake of securing messages.
Caesar decided that shifting each letter in the message would be
his standard algorithm, and so he informed all of his generals of
his decision, and was then able to send them secured messages.
Using the Caesar Shift (3 to the right), the message,
 "RETURN TO ROME" would be encrypted as,
"UHWXUA WR URPH’’
 Thus, the Caesar cipher is a shift cipher since the ciphertext
alphabet is derived from the plaintext alphabet by shifting each
letter a certain number of spaces.

5. A B C D E F G H I J
D E F G H I J K L M
K L M N O P Q R S T
N O P Q R S T U V W
 THE FAULT, DEAR BRUTUS, LIES NOT IN OUR STARS BUT
IN OURSELVES.
would be enciphered as
MAX YTNEM, WXTK UKNMNL, EBXL GHM BG HNK LMTKL
UNM BG HNKLXEOXL.

6. • A code is a system of signals that is used to represent
letters or numbers in transmitting a message. In other
CODES words, a code deals with phrases and sentences or
whole words. For example, this symbol means: =
"Send help at once.
• A cipher deals with letters. It is a message written in
letters in a predetermined code. This means that a
CIPHERS cipher is a system of communication that uses letters
instead of phrases and such.

7. •Aftergetting a hang of code- breaking by shifting the letters
forward and backwards, it is realized that there are 25 possible
way of deciphering a message. Further, in an attempt to secure
messages, symbols were used, vis a vis, A as =, B as * etc.
•So, what about coding messages another way?
For a long time, people thought this type of code would be really
hard to crack. It would take the enemy far too long to figure out
what letter of the alphabet each symbol stood for just by trying all
the possible combinations of letters and symbols. There are 400
million billion billion possible combinations!!!!

8. A special type of code was used by Mary Queen of Scots when she was
plotting against Elizabeth the First. Mary wanted to kill Elizabeth so
that she herself could become Queen of England and was sending
coded messages of this sort to her co-conspirator Anthony Babington.
Unfortunately for Mary, there is a very simple way of cracking this
code that doesn't involve trial and error, but which does involve,
surprise, surprise, maths.
Letter sent by Mary Queen of Scots to her co-conspirator Anthony
Babington. Every symbol stands for a letter of the alphabet.

9.  Way of solving the message:
 Letters in a language are pretty unusual because some get used
more often than other letters. In most of dictionary words and
names have the letter ‘’e’’, which most frequently occurs, then ‘t’,
then ‘a’, as shown below:

10. All Elizabeth the First's Spy-Master had to do to crack Mary's
code, was to look through the coded message and count the number
of times each symbol came up. The symbol that came up the most
would probably stand for the letter 'E'.
When you crack codes like this, by looking for the most common
letter, it's called 'frequency analysis', and it was this clever method of
cracking codes that resulted in Mary having her head cut off.
CHOP!!!
 Modern cryptography involves disciplines of computer,
mathematics and engineering.
Various coding/decoding methods are extensively used in
communication and computer technology , for storage and
transmission purpose.

11.  Semaphore, is a method of coding , where the configuration of
flags held by a signaller or the arms of a semaphore tower,
encodes parts of the message, typically individual letters and
numbers. Another person standing a great distance away can
interpret the flags and reproduce the words sent.
 Chappe telegraph, or Napoleonic semaphore is a system of
conveying information by means of visual signals, using towers
with pivoting shutters, also known as blades or paddles.
Information is encoded by the position of the mechanical
elements; it is read when the shutter is in a fixed position.
 Semaphore are virtually used to transmit information over long
distances. Some semaphore used which are used in navigation
ships for maritime security through visual signals or hand- held
flags are:

14. Although the machine was
Enigma machines were used by
initially invented for
German military for encryption
commercial purposes in Bank ,
and decryption of the secret
however it was found to be
messages during the world war
useful and extensively used
II.
during war period.
When a key is pressed, the
The Enigma machine is a circuit gets completed with
combination of mechanical and current flowing through various
electrical subsystems , components and ultimately
consisting of key boards, a set of lighting the display lamp
rotors and electrical circuits. indicating the output letter.

15.  The Polish & British mathematicians made great effort to
understand this machine and developed decryption methods.
The machine was based on mathematical models of encryption .
SET OF ENIGMA ROTORS

17. it was also extensively When using morse
Morse code is a method
used for early radio code, a dash is equal to
for transmitting
communication three dots. A space
information, using
beginning in the 1890s. between parts of the
standardized sequences
However, with the
of short and long marks same letter is equal to
development of more
or pulses - commonly one dot. A space
advanced
known as "dots" and between two letters is
communications
"dashes" - for the letters, equal to three dots and
technologies, the
numerals, punctuation a space between two
widespread use of Morse
and special characters of words is equal to five
code is now largely
a message. dots.
obsolete.

18.  CONVETING MORSE
CODE INTO ENGLISH
 Leonardo Da Vinci, Mona
Lisa
 INTO MORSE CODE
 ... .. -. -.-. --- -- .--. .-.. . - . -
... ..- - .--. .-.. . .- ... . --. .. ...- .
-- . .- .. -. -- .- - .... ...

20. THANKYOU
HAPPY CODING