Question

How to encrypt message in vigenere cipher using c#
code please write a c# code for an example

Answer 1

To encrypt a message using the Vigenère cipher in C#, a method that takes the plaintext and keyword can be created to perform the encryption. The keyword is adjusted to match the plaintext length, and each letter of the plaintext is shifted according to the keyword to produce the ciphertext.

Step-by-step explanation:

To encrypt a message using the Vigenère cipher in C#, you can write a method that takes the plaintext and the keyword as parameters and returns the encrypted message. Below is an example of how the code might look:

public static string VigenereEncrypt(string plaintext, string keyword)
{
string result = "";
keyword = keyword.ToUpper();
int keywordIndex = 0;

foreach (char c in plaintext.ToUpper())
{
if (char.IsLetter(c))
{
char offset = 'A';
int keywordPosition = (keyword[keywordIndex % keyword.Length] - offset);
int originalPosition = c - offset;
char encryptedChar = (char)((originalPosition + keywordPosition) % 26 + offset);
result += encryptedChar;
keywordIndex++;
}
else
{
result += c;
}
}

return result;
}

Remember to call this method with your plaintext and keyword to perform the encryption. The keyword is repeated or truncated to match the length of the plaintext, and each letter in the plaintext is shifted according to the corresponding letter in the keyword.