Cryptography - Reverse Cipher

What is a Reverse Cipher ?

A message can be encrypted by printing it in reverse order using a Reverse Cipher algorithm. So we can encrypt the words "Hi this is Robot" is encrypted to "toboR is siht iH". Simply reverse the reversed message to get the original message if you want to decode it. The process for encryption and decryption are the same.

So as we can see, the reverse cipher is a very weak cipher. It is visible from the ciphertext that it is just in reverse order.

But, we will utilize the Reverse Cipher program as our initial encryption program because its code is simple to understand.

Algorithm

Here's the algorithm for the Reverse Cipher for encryption and decryption both −

Encryption Algorithm

A plain text message will be the input of the encryption technique, and a ciphered text message will be the output. So, the following are the steps −

Step 1: Take input as a plain text message as input.
Step 2: Then reverse the order of characters in the plain text message to create the cipher text message.
Step 3: Return the cipher text message as output.

Decryption Algorithm

Additionally, a cipher text message will be the input of the decryption method, and a plain text message will be the result. So the steps for this algorithm is as follows −

Step 1: Take input as a cipher text message as input.
Step 2: After that reverse the order of characters in the cipher text message to get the original plain text message.
Step 3: Lastly return the plain text message as output.

Example

The reverse cipher is among the most basic types of ciphers. A plain text can be encrypted by simply reversing it's character order. The cipher text is the outcome. For example, the reverse cipher is used to encrypt the message "HAT" as "TAH." Using the reverse cipher, the message "HELLO WORLD" is encrypted as "DLROW OLLEH." Reversing the sequence is the only difference between the methods used to encrypt and decode a message. Thus, the message "TAH" would be decoded as "HAT". Decrypting the message "DLROW OLLEH" would be the "HELLO WORLD."

The reverse cipher's strength is how simple it is to use and comprehend. Children may use it to send their friends "secret messages." The reverse cipher does not perform particularly well if the purpose of encryption is to make our communication secure enough that a third party cannot read it, as it is a simple cipher to break.

Implementations

So we can implement this algorithm in different ways by using different modules of functions of Python. Let us see these ways one by one in the below sections −

Using Python
Using C++
Using Java

Using Python

As we have to implement the Reverse Cipher algorithm using Python so we will use python's string manipulation feature. We will use slicing to reverse the given plain text message inside the function.

Python's slicing functionality is used in the expression message[::-1] to change the message's character order.

In Python, reversing a string can be done by using the notation [::-1], which means to begin at the end of the string and move backward with a step size of -1.

Below is the implementation of Reverse Cipher using str manipulation of Python −

Example

def reverse_cipher(message):
   # Reverse the message using slicing
   reversed_message = message[::-1]
   return reversed_message

# function execution
message = "Hiii! this is a reverse cipher algorithm"
encrypted_message = reverse_cipher(message)
print("The Original Message: ", message)
print("The Encrypted message:", encrypted_message)

Following is the output of the above example −

Input/Output

The Original Message:  Hiii! this is a reverse cipher algorithm
The Encrypted message: mhtirogla rehpic esrever a si siht !iiiH

Using C++

This Code is implemented in C++, basically shows how a reverse cipher works. It starts with defining the key message. After that, it encrypts the message using the encrypt function, which reverses the behaviour of the message, and stores the outcome in an encryptedMessage. The encrypted message is then decrypted using the decrypt function, which returns the characters to their original form and records the result in a decrypted message. In order to show how to utilise the reverse cypher method for encryption and decryption, it displays the original message, the encrypted message, and the decrypted message at the end.

Here is the implementation of Reverse Cipher using C++ −

Example

#include <iostream>
#include <string>

std::string encrypt(std::string plaintext) {
   std::string ciphertext = "";
   for (int i = plaintext.length() - 1; i >= 0; i--) {
      ciphertext += plaintext[i];
   }
   return ciphertext;
}

std::string decrypt(std::string ciphertext) {
   std::string plaintext = "";
   for (int i = ciphertext.length() - 1; i >= 0; i--) {
      plaintext += ciphertext[i];
   }
   return plaintext;
}

int main() {
   std::string message = "Hello, This is a Reverse Cipher example!";
   std::string encryptedMessage = encrypt(message);
   std::string decryptedMessage = decrypt(encryptedMessage);

   std::cout << "Our Original Message: " << message << std::endl;
   std::cout << "The Encrypted message: " << encryptedMessage << std::endl;
   std::cout << "The Decrypted message: " << decryptedMessage << std::endl;

   return 0;
}

Following is the output of the above example −

Input/Output

Our Original Message: Hello, This is a Reverse Cipher example!
The Encrypted message: !elpmaxe rehpiC esreveR a si sihT ,olleH
The Decrypted message: Hello, This is a Reverse Cipher example!

Using Java

The main function of the provided Java code is to use the ReverseCipher class to encrypt the message and implement the reverse cipher method. It begins by explaining the main message, "Hello, Tutorialspoint!" Then, it uses the encrypt method to encrypt the message, which converts the message. Then, it parses the given message, redirecting the characters back to the original message. Finally, it prints the original message, the encrypted message, and the decrypted message to the console, displaying the encryption and decryption process.

Following is the implementation of Reverse Cipher using Java −

Example

// Class for reverse cipher
public class ReverseCipher {

   public static String encrypt(String plaintext) {
      StringBuilder ciphertext = new StringBuilder();
      for (int i = plaintext.length() - 1; i >= 0; i--) {
         ciphertext.append(plaintext.charAt(i));
      }
      return ciphertext.toString();
   }

   public static String decrypt(String ciphertext) {
      StringBuilder plaintext = new StringBuilder();
      for (int i = ciphertext.length() - 1; i >= 0; i--) {
         plaintext.append(ciphertext.charAt(i));
      }
      return plaintext.toString();
   }

   public static void main(String[] args) {
      String message = "Hello, Tutorialspoint!";
      String encryptedMsg = encrypt(message);
      String decryptedMsg = decrypt(encryptedMsg);

      System.out.println("The Original message is: " + message);
      System.out.println("The Encrypted message is: " + encryptedMsg);
      System.out.println("The Decrypted message is: " + decryptedMsg);
   }
}

Following is the output of the above example −

Input/Output

The Original message is: Hello, Tutorialspoint!
The Encrypted message is: !tniopslairotuT ,olleH
The Decrypted message is: Hello, Tutorialspoint!

Features

Below are some feature of reverse cipher algorithm −

The Reverse Cipher is used to change a plaintext string into ciphertext by reversing it according to the given pattern.
Both encryption and decryption work in the same way.
In the decryption process the user only needs to reverse the cipher text for getting the plain text.

Drawback

The big drawback of the reverse cipher algorithm is that it is very weak. So the hacker can easily break the ciphertext to know the actual or original message. Hence, reverse cipher is not considered a good option to maintain a secure communication channel.

So Reverse Cipher can be used for educational purposes or for very basic encryption needs. And this algorithm is not suitable for securing confidential information or communication channels as it is vulnerable.

Summary

Overall Reverse Cipher is a very simple cryptography algorithm or method with the help of it the characters of a message are reversed to create the ciphertext. As it is easy to understand and implement. It is also very weak in terms of security. Both encryption and decryption have the same process of reversing the text.

But, this algorithm is not a reliable way for securing very sensitive information. As it is easy to crack and hack which means it is very vulnerable. So, it can be used for educational purposes.