Data Communications Networking Devices - 4th Ed.pdf

786 ___________________________________________________________ SPECIALIZED DEVICESmicroprocessors it is easy to construct a device to continuously change their indicesafter a certain period of transmission or to change the cells, or both.A variation of the checkerboard technique is accomplished through theutilization of a keyword which is commonly referred to as a Vigenere cipher technique.In its simplest form the Vigenere cipher consists of a table of alphabets, asshown in Figure 7.36. For ease of remembrance, a meaningful phrase or mnemonicFigure7.36 Vigenere cipher. A one-to-one correspondence between the plain text andthe characters of a key is used to develop the cipher text. Here,the intersection of the plaintext character I with the key character S produces a cipher text character A