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                    Which wireless media can be used to exchange data over a short distance?








                                                                                           21 st   #Communication
                  LAB ACTIVITY                                                           Century   #Technology Literacy
                                                                                           Skills

                  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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                                                                                  21 st
                                                                                                        []
                                                                                     #Computational Thinking
                                                                                Century
                                                                                 Skills
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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  cipher  text.  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 cipher text, the letter of cipher text is replaced by letter three
                places before it.


                Example:
                  Plain text: Today is Sunday


                  Cipher text: 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 cipher text.






             22   Pro (Ver. 5.0)-VIII
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