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    (ii)   Iris and Retinal Recognition: Biometrics that analyse the complex and unique characteristics
                            of the eyes can be divided into two different types:
                                   Iris biometrics: The iris is the coloured ring of tissue that surrounds the pupil of the eye.
                              An iris recognition system uses a video camera to capture the sample, while the software
                              compares the resulting data against stored templates.

                                   Retina biometrics:  Retina  is  the  layer  of  blood  vessels  at  the  back  of the  eye.  A  retinal
                              recognition system projects an infrared light beam into eye, which is placed closed to the
                              signal receiver. The unique patterns of the retina are then extracted and analysed by the
                              system to grant access.

                                                                 Tech Fact
                         For iris and retinal recognition, it is advisable to remove eye glasses and contact lenses.

                           (iii)  Voice Recognition: The term voice recognition refers to identifying the person who is speaking,
                            rather than what he/she is saying. Recognising the speaker can simplify the task of translating
                            speech into system trained on a specific person’s voice, or it can be used to authenticate or
                            verify the identity of a speaker as part of a security process.
                                   Encryption: Encryption is the process of converting data and information into a form, called
                              ciphertext, that cannot be easily understood by unauthorised people.

                                   Decryption: Decryption is the process converting encrypted data back into its original form,
                              so that it can be understood.
                            The use of encryption and decryption is as old as the art of communication. In earlier times,
                          particularly during wars, a cipher, often referred to as a code, was used to prevent enemies from
                          accessing the contents of transmissions.

                            Simple  ciphers  include  the  substitution  of letters  for numbers, the  rotation  of letters  in the
                          alphabet,  and the ‘scrambling’  of voice  signals by inverting the sideband  frequencies.  Some
                          complex ciphers work according to sophisticated computer algorithms that rearrange the data
                          bits in digital signals. For example, take a look at the following code:
                                                          Jogpsnbujpo Qspufdujpo
                            Do you understand the code or does it make any sense? No. This is because it is written in
                          encrypted form. However, if you know the decryption method you can decipher it.

                            Try replacing every letter in the message with the letter precedes it in the alphabet. You will find
                          that the code is:
                                                            Information Protection

                            HOW TO BACKUP YOUR IMPORTANT FILES?

                     In this section, you will learn how to back up your computer files. This is an important step in ensuring
                     the safety of your data. Have you ever lost any important documents, photos or other files? Imagine
                     what would happen if your computer suddenly stopped working.

                                                                                          Computer Safety and Security  69

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