Network Security: Transposition Cipher Techniques

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Unlock the secrets of transposition cipher techniques with our comprehensive guide. Discover how to rearrange letters and words to encrypt your messages, bolstering their security. Learn about popular methods like columnar transposition and rail fence cipher, and enhance your understanding of cryptography. Explore our in-depth tutorials and examples, empowering you to master the art of transposition ciphers. Start encrypting and decoding messages like a pro today!

Table of Contents

Transposition Cipher

Transposition Cipher allows encrypting a message to convert it into cipher text without altering the original plain text. It is the key-less process of encrypting and decrypting the texts.

Rail Fence Technique

Rail Fence Technique is the process of, without changing the original plain text, generating the cipher text from the plain text by rearranging the plain text. Unlike Substitution Cipher, it does not need any key to convert plain text into cipher text. It allows you to write the message in a zigzag format. The rails represent the number of lines used in the zigzag format.  

Steps in Rail Fence Cipher 

  1. Choose the number of Rails: Rails represents the number of rails or rows to be used in the encryption and decryption process.
  2. Write the message: Write the message in the zigzag format along the rails, starting from the top rail and moving down. Place each letter in consecutive order, ignoring spaces and punctuation.
  3. Read off the Cipher: Read the characters from left to right, row by row, starting from the top rail.
  4. Decryption: To decrypt the message, write the cipher text in the Zigzag pattern. Consider the using same number of rail fences but including the number of columns according to the number of letters in the ciphertext.

    Now, we place the first letter in the top left square and dash diagonally downwards where the letters will be. When we get back to the top row, we place the next letter in the ciphertext. Continue like this across the row, and start the next row when you reach the end.

Example 1:

Choose the Number of Rails: Let’s use 2 Rails for this demonstration.

Write the Message: The message is “HELLOWORLD”

The zigzag pattern on two rails would look like this:

H

 

L

 

O

 

O

 

L

 
 

E

 

L

 

W

 

R

 

D

Read off the Cipher: Read the characters from left to right, row by row, starting from the top rail. 

Encrypt message is 

“HLOOLELWRD” 

Decrypt the message “HLOOLELWRD”

Using a table with 2 rows because of 2 Rail Fence and 10 columns because of the ciphertext length.

Now, we place the first letter in the top left square and dash diagonally downwards where the letters will be. When we get back to the top row, we place the next letter in the ciphertext. Continue like this across the row, and start the next row when you reach the end.

H

 

L

 

O

 

O

 

L

 
 

 

 

 

 

 

H

 

L

 

O

 

O

 

L

 
 

E

 

L

 

W

 

R

 

D

From this, we can now read the plaintext off following the diagonals or column-wise to get “HELLOWORLD”.

Example 2:

Choose the Number of Rails: Let’s use 3 Rails for this demonstration.

Write the Message: The message is “HELLOWORLD”

The zigzag pattern on three rails would look like this:

H

   

O

   

L

 
 

E

 

L

 

W

 

R

 

D

  

L

   

O

   

Read off the Cipher: Read the characters from left to right, row by row, starting from the top rail. 

Encrypt message is 

“HOLELWRDLO” 

Decrypt the message “HOLELWRDLO”

Using a table with 3 rows because of 3 Rail Fence and 10 columns because of the ciphertext length.

Now, we place the first letter in the top left square and dash diagonally downwards where the letters will be. When we get back to the top row, we place the next letter in the ciphertext. Continue like this across the row, and start the next row when you reach the end.

H

   

O

   

L

 
 

 

 

 

 

  

   

   

 

H

   

O

   

L

 
 

E

 

L

 

W

 

R

 

D

  

   

   

 

H

   

O

   

L

 
 

E

 

L

 

W

 

R

 

D

  

L

   

O

   

From this, we can now read the plaintext off following the diagonals to get “HELLOWORLD”.

Example 3:

Choose the Number of Rails: Let’s use 3 Rails for this demonstration.

Write the Message: The message is “ILIVEINDELHI”

The zigzag pattern on three rails would look like this:

I

   

E

   

E

   
 

L

 

V

 

I

 

D

 

L

 

I

  

I

   

N

   

H

 

Read off the Cipher: Read the characters from left to right, row by row, starting from the top rail. 

Encrypt message is 

“IEELVIDLIINH” 

Decrypt the message “IEELVIDLIINH”

Using a table with 3 rows because of 3 Rail Fences and 12 columns because of the ciphertext length.

Now, we place the first letter in the top left square and dash diagonally downwards where the letters will be. When we get back to the top row, we place the next letter in the ciphertext. Continue like this across the row, and start the next row when you reach the end.

I

   

E

   

E

   
 

L

 

V

 

I

 

D

 

L

 

I

  

I

   

N

   

H

 

 

I

   

E

   

E

   
 

 

 

 

 

 

  

   

   

 

 

I

   

E

   

E

   
 

L

 

V

 

I

 

D

 

L

 

I

  

   

   

 

 

I

   

E

   

E

   
 

L

 

V

 

I

 

D

 

L

 

I

  

I

   

N

   

H

 

From this, we can now read the plaintext off following the diagonals to get “ILIVEINDELHI”.

Row Transposition Cipher – In this technique, each letter of the plain text is written to each box one by one starting from the first row. A random key is generated according to the column numbers taken into the table to encrypt the message. Finally, to get the cipher text, write each letter one by one (in the down position) to column-wise according to the random key.

1

2

3

4

 

H

E

L

L

O

W

O

R

L

D

  

Key: 3412

Ciphertext: LOLRHOLEWD

Conclusion

Transposition ciphers offer a simple encryption method, but they tend to provide weaker security compared to more advanced encryption algorithms. These ciphers are more suitable for educational purposes, puzzles, or building blocks for more complex cryptographic systems.

There are various transposition ciphers, including the Rail Fence technique and other more intricate variations. Each cipher employs different rules and patterns to rearrange the elements, providing a different level of complexity and security.

Overall, we learned how to encrypt the original message to cipher text with the help of Transposition Cipher techniques. While transposition ciphers have their place in cryptography, it is essential to consider their limitations and explore more advanced encryption methods for securing sensitive data.

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