public CaesarsCipherDecryptor(TextMessage msg, int key)
{
msg.Message = msg.Message.ToUpper();
this.Message = "";
for (int i = 0; i < msg.Message.Length; i++)
{
int nextChar = msg.Message[i] - 'A';
nextChar = (nextChar - key) % 26;
this.Message += (char)(nextChar + 'A');
}
}
static void Main(string[] args)
{
Console.Write("Enter String: ");
TextMessage message = new TextMessage();
message.Message = Console.ReadLine();
TextMessage caesarsCipherEncryptor = new CaesarsCipherEncryptor(message, 7);
Console.WriteLine("Encrypting message: " + caesarsCipherEncryptor.Message);
TextMessage caesarsCipherDecryptor = new CaesarsCipherDecryptor(caesarsCipherEncryptor, 7);
Console.WriteLine("Decrypting message: " + caesarsCipherDecryptor.Message);
Console.ReadLine();
}
public CaesarsCipherEncryptor(TextMessage msg, int key)
{
// From This is CS 50. Harvard College Fall 2009 problem set 2
// Caesar's Cipher
// If p is some plaintext (i.e., an unencrypted message), pi is the i th character in p,
// and k is a key (i.e., a non-negative integer), then each letter, ci, in the ciphertext, c, is computed
// as:
// ci = (pi + k) % 26
msg.Message = msg.Message.ToUpper();
this.Message = "";
for (int i = 0; i < msg.Message.Length; i++)
{
int nextChar = msg.Message[i] - 'A';
nextChar = (nextChar + key) % 26;
this.Message += (char)(nextChar + 'A');
}
}
