Write a Program For columnar transposition cipher.
Playfair Cipher: The Playfair cipher is a written code or symmetric encryption technique that was the first substitution cipher used for the encryption of data. Introduced in 1854, it involved the use of keys that arrange alphabetical letters in geometric patterns in order to encode messages. The Playfair cipher is also known as the Playfair.
Caesar cipher, monoalphabetic cipher, homophonic substitution cipher, Polyalphabetic Cipher, Playfair cipher, rail fence, One time pad, hill cipher are some of the examples of cryptography techniques. Cryptography deals with various security principles which are as follows.
The Playfair cipher was invented in 1854 by Charles Wheatstone, but named after lord Playfair who heavily promoted the use of the cipher. It is a polygraphic substitution cipher, which encrypts pair of letters instead of single letters. This makes frequency analysis much more difficult, since there are around 600 combinations instead of 26.
The Playfair cipher or Playfair square, is a manual symmetric encryption technique and was the first literal digraph substitution cipher. The scheme was invented in 1854 by Charles Wheatstone, but bears the name of Lord Playfair who promoted the use of the cipher. The Playfair cipher uses a 5 by 5 table containing a keyword or phrase. Memorization of the keyword and 4 simple rules are all that.
The Playfair cipher encrypts pairs of letters (digraphs), instead of single letters as is the case with simpler substitution ciphers such as the Caesar Cipher. Frequency analysis is still possible on the Playfair cipher, however it would be against 600 possible pairs of letters instead of 26 different possible letters. For this reason the Playfair cipher is much more secure than older.
In the program we are implementing Modified Caesar cipher which is an example of substitution cipher. Program consist of two methods encrypt and decrypt. The encrypt method has two parameter one the plain text and second is key. In Modified Caesar cipher each alphabet of plain text is may not necessarily replaced by key bits down the order instead the value of key is incremented and then it is.
To encrypt a message using the Rail Fence Cipher, you have to write your message in zigzag lines across the page, and then read off each row. Firstly, you need to have a key, which for this cipher is the number of rows you are going to have. You then start writing the letters of the plaintext diagonally down to the right until you reach the number of rows specified by the key. You then bounce.