¿Qué tipo de cifrado es el cifrado Vigenere?

What kind of cipher is The Vigenere cipher?

Vigenère Cipher. Vigenere Cipher is a method of encrypting alphabetic text. It uses a simple form of polyalphabetic substitution. A polyalphabetic cipher is any cipher based on substitution, using multiple substitution alphabets .The encryption of the original text is done using the Vigenère square or Vigenère table.

The Vigenère square or Vigenère table, also known as the tabula recta, can be used for encryption and decryption. In a Caesar cipher, each letter of the alphabet is shifted along some number of places. For example, in a Caesar cipher of shift 3, Awould become D, Bwould become E, Ywould become Band so on.

Auguste Kerckhoffs improved on Kasiski’s method by matching each “column’s letter frequencies to shifted plaintext frequencies to discover the key letter (Caesar shift) for that column.” Once the code-breaker knows each letter in the secret key, all they have to do is decrypt the cipher text using a Vigenere square.

In fact, any message encrypted with a Vigenere cipher will produce many such repeated bigrams. Although not every repeated bigram will be the result of the encryption of the same plaintext bigram, many will, and this provides the basis for breaking the cipher.

Vigenere Cipher is kind of polyalphabetic substitution method. It is used for encryption of alphabetic text. For encryption and decryption Vigenere Cipher Table is used in which alphabets from A to Z are written in 26 rows. Also Read: Caesar Cipher in C and C++ [Encryption & Decryption]

Hence, we will write the program of the Vigenère Cipher algorithm in C++, although, it’s very similar to C. The following is the Caesar Cipher encryption algorithm program in C++. The following is the Vigenère Cipher decryption algorithm program in C++.

Here we have to obtain a key by repeating the given key till its length becomes equal to original message length. For encryption take first letter of message and key i.e. T and W. Take the alphabet in Vigenere Cipher Table where T row and W column coincides i.e. P. Repeat the same process for all remaining alphabets in message text.