Proposal to add Vigenère Cipher program in Java.

[Immanuel-Anthony]

Proposal :

I would like to add a Vigenère Cipher program in Java to =>

Encrypt Data Decrypt Data Thank you

[trishan9]

Ok, I assign this issue to you!

[trishan9]

Assigned to you, @Immanuel-Anthony

[trishan9]

Happy contribution!

[jayendranar02]

I want to contribute on this issue please assign me .

[trishan9]

I want to contribute on this issue please assign me .

Sure, I will assign this issue to you @jayendranar02

[trishan9]

Issue has been assigned to you @jayendranar02!

[trishan9]

Happy contribution!

[jayendranar02]

import java.util.Scanner;

public class VigenereCipher {

// Method to encrypt plaintext using Vigenère Cipher
public static String encrypt(String plaintext, String keyword) {
    StringBuilder encryptedText = new StringBuilder();
    keyword = generateKeyword(plaintext, keyword);

    for (int i = 0; i < plaintext.length(); i++) {
        char p = plaintext.charAt(i);
        char k = keyword.charAt(i);
        // Encrypt only alphabetic characters
        if (Character.isLetter(p)) {
            char base = Character.isUpperCase(p) ? 'A' : 'a';
            int encryptedChar = (p + k - 2 * base) % 26 + base;
            encryptedText.append((char) encryptedChar);
        } else {
            encryptedText.append(p); // Non-alphabetic characters remain unchanged
        }
    }
    return encryptedText.toString();
}

// Method to decrypt ciphertext using Vigenère Cipher
public static String decrypt(String ciphertext, String keyword) {
    StringBuilder decryptedText = new StringBuilder();
    keyword = generateKeyword(ciphertext, keyword);

    for (int i = 0; i < ciphertext.length(); i++) {
        char c = ciphertext.charAt(i);
        char k = keyword.charAt(i);
        // Decrypt only alphabetic characters
        if (Character.isLetter(c)) {
            char base = Character.isUpperCase(c) ? 'A' : 'a';
            int decryptedChar = (c - k + 26) % 26 + base;
            decryptedText.append((char) decryptedChar);
        } else {
            decryptedText.append(c); // Non-alphabetic characters remain unchanged
        }
    }
    return decryptedText.toString();
}

// Generate the repeated keyword based on the length of the text
private static String generateKeyword(String text, String keyword) {
    StringBuilder result = new StringBuilder();
    int j = 0; // Index for keyword

    for (int i = 0; i < text.length(); i++) {
        char currentChar = text.charAt(i);
        if (Character.isLetter(currentChar)) {
            result.append(keyword.charAt(j % keyword.length()));
            j++;
        } else {
            result.append(currentChar); // Non-alphabetic characters remain unchanged
        }
    }
    return result.toString();
}

public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);

    System.out.println("Enter the plaintext:");
    String plaintext = scanner.nextLine();

    System.out.println("Enter the keyword:");
    String keyword = scanner.nextLine();

    String encrypted = encrypt(plaintext, keyword);
    System.out.println("Encrypted Text: " + encrypted);

    String decrypted = decrypt(encrypted, keyword);
    System.out.println("Decrypted Text: " + decrypted);

    scanner.close();
}

}

[jayendranar02]

Explanation of the Code--->

Encrypt Method:- Encrypts the given plaintext using the specified keyword. It generates a repeated keyword to match the length of the plaintext and performs the encryption for each letter.

Decrypt Method:- Decrypts the given ciphertext using the same keyword. It similarly generates a matching keyword and applies the decryption logic.

Generate Keyword:- This method constructs a keyword of the same length as the input text, skipping non-alphabetic characters. User Interaction:

The main method handles user input for plaintext and keyword, performs the encryption and decryption, and displays the results.

[jayendranar02]

Conclusion---> This proposal outlines a complete Vigenère Cipher program in Java that can encrypt and decrypt text. The provided code is ready for integration and testing. By following this plan, we can successfully add a functional and educational cryptographic tool to our project.