Vigenere Cipher (Polyalphabetic Cipher) in Hindi/Urdu | 9th Computer Chapter 4 | Lecture - 10

4.3.2.2 Vigenere Cipher Vigenere cipher is another substitution cipher, which uses a table known asVigenere Cipher table for substituting the letters of plaintext. Vigenere Cipher Table: The table consists of 26rows and 26 columns, where the 1st row contains the original alphabets from A -Z. In each subsequent row the alphabet is shifted by one letter to the right. All the columns are labeled by alphabets from A - Z, and all the rows are also labeled by alphabets from A - Z. Vigenere Cipher Method: In this method, we have a substitution key that is combined with the plaintext to generate the ciphertext. We encrypt each letter of the plaintext by finding that letter in column labels of the Vigenere table and in that column, we find a letter that is in front of the row label for the respective letter of the key. We continue this process until all the text is finished. Example: Let's assume that we want to encrypt "PAKISTAN" with the help of substitution key "ZINDABAD". We find 'P' (first letter of plaintext) in column labels and 'Z' (first letter of substitution key) in row labels. We can observe that the row and the column meet at letter 'O' as marked with yellow color in So, the letter 'P' is converted to 'O'. Similarly, we find the letter 'An' in column labels which is the first column (marked with green color). And we find the letter T in the row labels. Row and the column meet at the letter T. So, 'A' is replaced with T in this way the word "PAKISTAN" is converted to cypher text "OIXLSUAQ" Important Note: If the key has less number of letters, then we repeat the letters of that key from beginning. For example, to encrypt the text “PAKISTAN" having 8 letters with the key "BEAUTY" having 6 letters, we repeat the letters of the key to make them equal in length to the given plaintext. So the key becomes "BEAUTYBE" having same number of letters and this key is called interim ciphertext. #DigitalEducation, #DigitalEducationLatestNews, #DigitalEducationShahbazAli, #Vigenere cipher #Polyalphabetic substitution cipher #Working of vigenere cipher #What is vigenere? #Cryptanalysis of vigenere cipher #Vigenere cipher cryptanalysis #Vigenere cipher auto key #Vigenere cipher example #Example of vigenere cipher #Cipher #Vigenere #Polyalphabetic cipher #Vigenere #9thComputerChapter4 #9ClassComputerChapter4 #Class9ComputerChapter4 #ComputerClass9SolvedUnit4 #Unit4SolvedComputer9Class #9ComputerNewCourse #DataandPrivacy, #9ClassComputerInUrdu #digitaleducation #DigitalEducationShahbazAli #computerscience9thclassbook #computersciencebookforclass9 #9thcomputersciencebook #computersciencenewbook9thclass #computerscience9thclass #Class9computersciencebook #computerscience9thclassbook #class9computerscience #9classcomputersciencebook #computersciencenewbook9thclass #9thcomputerscience #computerscienceclass9book #computerscience9classbook #computerscienceclass9newbook #keybookofcomputersciencefor9thclassfederalboard #computerscience9thclassbookfederalboard #9thclasscomputersciencenewbook #computersciencebook9thclass #9thclassbookcomputerscience #computerscienceofclass9 #9thclasscomputersciencekeybook Computer Science 9th class Lecturer of Computer Science By Sir Shahbaz Ali For any query or private tutoring contact (0309-0334424) shahbazalicp@gmail.com