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Which wireless media can be used to exchange data over a short distance?
LAB ACTIVITY Communication
Visit your computer lab and perform the following actions:
▶ Surf the Internet and find out the various types of networks and how they work.
▶ Make a presentation on collected information and also add relevant pictures.
▶ Show your presentation in front of your class.
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For transmitting our data over a network in a safe and secure manner, various cipher techniques
are used to convert our plain text message into ciphertext. For this conversion, different techniques
are used. Some of them are explained below:
Substitution Technique
In this technique, we simply replace the letters in our message with other letters or symbols.
One of the simplest substitution techniques is the Caesar Cipher which was developed by Julius
Caesar. In this technique, each letter of the plain text is replaced by the letter three places ahead
of it. Therefore, to decrypt the ciphertext, the letter of ciphertext is replaced by the letter three
places before it.
Example:
Plain text: Today is Sunday
Ciphertext: wrgdb lv vxqgdb
We have simply replaced each letter of the plain text with the letter three places ahead of it.
Transposition Technique
In this technique, the identity of the letters remains the same but their positions are changed to
create the ciphertext.
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