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Communication is about conveying messages to the other party or to a group. These messages carry certain information. The medium through which information is communicated can be words or signs. The basic need to communicate has evolved languages, and language is used as a medium to share information, ideas, and feelings. There are three main types of communication: oral communication, written or verbal communication, and non-verbal communication.

During oral communication, parties communicate through voice as a medium. The parties involved in the oral communication are expected to be able to convey the message, which clearly expresses all their feelings, needs, wants, values, beliefs, and thoughts. Again, both the sender and the receiver use the same language so that both can understand. The sender can speak and the receiver can listen and vice versa, in order to exchange information. The tone of voice or the gap of silence makes a huge difference in oral communication.

During non-verbal communication, the communication is through the use of body language, gestures, facial expressions, and signs. These expressions may be well structured or unstructured. The semaphores that were used by military, sign language used by deaf persons, and gestures, postures, facial expression, and eye contact used by humans are a few of the examples. Semaphore Flags are the telegraphy system that conveys information at a distance

by means of visual signals with handheld flags, rods, disks, paddles, or occasionally bare or gloved hands. Information is encoded by the position of the flags and is read when the flag is in a fixed position. Semaphores were adopted and widely used (with hand-held flags replacing the mechanical arms of shutter semaphores) in the maritime world

in the nineteenth century. It is still used during underway replenishment at sea and is acceptable for emergency communication in the daylight or while using lighted wands instead of flags at night. Even verbal communication may have underlying non-verbal signals like stress, rhythm, and intonation, which may convey a different meaning to the person tuned to such signals or intended recipients of such signals. Non-verbal communications can be considered coded and may have different meanings to different recipients. Many times, non-verbal communication or gestures complement or negate the words spoken and may emphasize the words spoken or give them a different meaning than the meaning of the words spoken. Strong observation and hearing is required to understand the non-verbal communications, particularly if they are embedded with secret signals.

Sometimes, information needs to be communicated to only a few people and understood by only a few people, like the messages sent by kings, military commanders, diplomats, and other military people. Since the early days of writing, kings and commanders in India used secret codes to send messages to other kings and commanders outside the state. During war time, secret messages were sent by a network using simple alphabetic substitutions often based on phonetics. The ancient Chinese used the ideographic nature of their language to hide meanings of words. In

the past, sensitive messages were transported through trusted persons, were guarded and were stored in a secure environment, thus ensuring the security of information. Julius Caesar (50 B.C.) is credited with the invention of cipher code to protect the confidentiality of information in order to prevent secret messages from being read by others.

The Caesar cipher is named after Julius Caesar, who used simple coding techniques to protect messages of military significance. Caesar used a simple technique of replacing each letter in the plaintext by a letter shift of 3. He used this method for all his military communications.4

It is unknown how effective the Caesar cipher was at that time, but there are incidences in the nineteenth century where the personal advertisements section in newspapers would sometimes be used to exchange messages encrypted using simple cipher schemes. According to Kahn (1967), there were instances of lovers engaging in secret communications coded in Caesar cipher in The Times personal ads. More complicated Caesar cipher was also in use by the Russian army during war times because it was difficult for their enemies to decipher.5

The need for communication not only helped in the development of many languages, but also the basic need to communicate with those at a distance resulted in the invention of telegraphs and telephones. The telegraph is a communication system invented by Samuel Morse (1791–1872), in which information is transmitted over a wire

through a series of electrical pulses called Morse code. Morse code is a series of dots and dashes.6 The pattern of dots and dashes were assigned to letters of the alphabet, numerals, and punctuation marks. Telegraph operators used Morse code to code the plain text messages before transmission over the electric cable and at the receiving end, where operators translated the Morse code back to plain English. The electric telegraphs transformed how wars were fought, and how military commanders sent their messages to distant soldiers and commanders. Rather than taking weeks to deliver messages by horse carriages and trusted messengers, information could be exchanged between two telegraph stations almost instantly. There are records of using telegraph systems during the Crimean war of 1853–1856. In

the 1860s, the Russian army used telegraphs for communication between field officers and headquarters. After the telegraph, further inventions led to distance-based communication, such as radio and telephone.

During the early days of distance-based communications, messages were disguised to protect the confidentiality and to avoid them being revealed to others. It is natural that the messages sent through the telegraph, telephone,

and eventually the radio, were also expected to be disguised in the form of codes. With the advent of distance communication methods using radio signals, the use of cryptography became very important, especially for coordinating military operations. Historically, we know that the French, American, and German armies were actively using various kinds of cipher methods during World War I.

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