code2begin

In this post we discuss a method to encrypt your files using  Vigenère Cipher . The  Vigenère cipher  is a method of  encrypting   alphabetic  text by using a series of interwoven  Caesar ciphers  based on the letters of a keyword.  It is a form of  polyalphabetic substitution . Even though the vigenere cipher is easy to understand and implement, for three centuries it resisted all attempts to break it. In order to encrypt a given message, a table of alphabets can be used, termed a  tabula recta , The following is the image of the Table. the above table   consists of the alphabet written out 26 times in different rows, each alphabet shifted cyclically to the left compared to the previous alphabet.  At different points in the encryption process, the cipher uses a different alphabet from one of the rows. The alphabet used at each point depends on a repeating keyword. Now let us consider an example...

In the previous blog post we discussed about Encryption of a file using Caesar Cipher, in this post we discuss a method to decrypt the same file. If you want to view the previous post on Encryption using Caesar Cipher click HERE . Decryption is a process of decoding the encrypting the encrypted file, to do this we need to know 2 things, the first is the method of encryption and the second is cipher key which in this case is our shift value. once we know these things we can start deciphering the files.  As caesar cipher is a substitution cipher, shift value decides which value is replaced with another value, in encryption we replace each letter by the letter to its right by shift value position, hence now we need to do the opposite, we have to replace each letter by the letter to its left by shift value positions. So for shift value of 3 we have, Plaintext :          ABCDEFGHIJKLMNOPQRSTUVWXYZ  decipher text :     XYZ AB...

List of All Programs The Following is the List of all the programs on my Blog Math Programs Square Root of a number using Babylonian Method Finding The Next Smallest Palindrome Finding the Armstrong Numbers Factorial of a number GCD using Euclid's Algorithm Check if a number is Fibonacci Number or not LCM of 2 numbers Trailing Zeros in factorial of a number Sorting Algorithms Bubble Sort Algorithm Selection Sort Algorithm Insertion Sort Algorithm Shell Sort Algorithm Counting Sort Algorithm Linked List Programs Simple Singly Linked List Linked List in C++ Linked List in Python Linked List in Java Doubly Linked List Finding Kth element from the end of Linked List Delete a node from Linked List Delete Kth element from the end of Linked List Rotate Linked List in an Anti-clockwise direction Reversing first K nodes of a Linked List Binary Search Tree Left View of Binary Tree Righ...