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In an earlier post we discussed a method to encrypt a string using Vigenere Cipher, in this post we see the method to decrypt the encrypted message. 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 depe...

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...

In this post we will discuss what is cryptography and how can we encrypt our files using Caesar Cipher. First Things first let us first understand the what is cryptography, according to wikipedia, " Cryptography  is the practice and study of techniques for  secure communication  in the presence of third parties called  adversaries" Simply stated it is passing messages between 2 user using a channel that is not secure yet the intruders trying to get steal information will not be able to understand messages directly as the messages are encrypted. In order to encrypt a message, we change the contents of message such that only the intended receiver of the message is able to decode it. Let us now discuss Caesar Cipher, sometime also called as shift cipher is a ciphering technique that is one of the most simple and widely known techniques of encryption. This technique uses a substitution technique in which for each letter in our message we have a letter...