Wednesday, October 13, 2021

Rail fence Cipher | Transposition Cipher | Zigzag cipher

Introduction

There are basically two types of symmetric cipher: Substitution Cipher, Transposition Cipher.

Substitution Cipher: A substitution is a technique in which each letter or bit of the plaintext is substituted or replaced by some other letter, number or symbol to produce cipher text. For Example, ABC  XYZ.

Types of Substitution Cipher: Caesar Cipher, Monoalphabetic Cipher, Vigenère Cipher, Playfair Cipher, One time pad cipher (Vernam cipher), Hill Cipher.

Transposition Cipher: In transposition technique, there is no replacement of alphabets or numbers occurs instead their positions are changed or reordering of position of plain text is done to produce cipher text. For Example, ABCDE    BADEC.

Types of Transposition Cipher: Rail Fence Cipher, Columnar Transposition Cipher.

 

Rail Fence Cipher/Zigzag Cipher

The rail fence cipher (sometimes called zigzag cipher) is a transposition cipher that jumbles up the order of the letters of a message using a basic algorithm. It is one of the easy techniques of transposition cipher in which position of letters are changed. The rail fence cipher works by writing your message on alternate lines across the page, and then reading off each line in turn. Note that all white spaces have been removed from the plain text.

 

Example – 1 (Depth/Key = 2)

Plaint Text: SECRET MESSAGE (Depth/Key = 2)

To encode this message, we will first write over two lines (the “rails of the fence”) as follows:

The ciphertext is then read off by writing the top row first, followed by the bottom row

Cipher Text: S C E M S A E E R T E S G

 

Example – 2 (Depth/Key = 3)

Plaint Text: SECRET MESSAGE (Depth/Key = 3)

To encode this message, we will first write over two lines (the “rails of the fence”) as follows:

The ciphertext is then read off by writing the top row first, followed by the bottom row.

Cipher Text: S E S E E R T E S G C M A

To learn more about Rail fence (Zigzag) cipher, Click here

        
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