public static string Decipher(string raw)
{
string originalDecipheredString = "";
char[] originalDecipheredChar = new char[raw.Length / 2];
List <string> decipheredParts = new List <string>();
for (int i = 0; i < (raw.Length / 2); i++)
{
originalDecipheredChar[i] = raw[(i * 2) + 1];
}
originalDecipheredString = new string(originalDecipheredChar);
int len = originalDecipheredString.Length / 4;
for (int i = 0; i < 4; i++)
{
decipheredParts.Add(originalDecipheredString.Substring(i * len, len));
decipheredParts[i] = VigenèreCipher.Decrypt(decipheredParts[i], keywords[i]);
}
char[] decipheredChar = new char[len];
for (int j = 0; j < len; j++)
{
int sum = 0;
for (int k = 0; k < 4; k++)
{
sum += decipheredParts[k].ToCharArray() [j] - 65;
}
sum += 32;
decipheredChar[j] = (char)sum;
}
return(new string(decipheredChar));
}
public void Vigenère()
{
VigenèreCipher cipher = new VigenèreCipher();
const string key = "Lemon";
const string plaintext = "Attack at dawn";
const string ciphertext = "Lxfopv ef rnhr";
Assert.AreEqual(ciphertext, cipher.Encrypt(plaintext, key));
Assert.AreEqual(plaintext, cipher.Decrypt(ciphertext, key));
}
public static string Encipher(string value)
{
string randomKey = Keys.RandomKey(value.Length * 4);
List <string> cipheredParts = new List <string>();
List <List <char> > keys = new List <List <char> >()
{
new List <char>(),
new List <char>(),
new List <char>(),
new List <char>()
};
var charArray = value.ToCharArray();
int a = 0, b = 0;
for (int i = 0; i < value.Length; i++)
{
a = 0;
b = 0;
int temp = charArray[i] - 32;
int temp_part = temp / 4;
int temp_parts_excess = temp % 4;
if (i % 2 == 0)
{
a = temp_parts_excess;
}
else
{
b = temp_parts_excess;
}
keys[0].Add((char)(temp_part + a + 65));
keys[1].Add((char)(temp_part + 65));
keys[2].Add((char)(temp_part + 65));
keys[3].Add((char)(temp_part + b + 65));
}
for (int i = 0; i < 4; i++)
{
cipheredParts.Add(new string(keys[i].ToArray()));
cipheredParts[i] = VigenèreCipher.Encrypt(cipheredParts[i], keywords[i]);
}
var cipheredString = cipheredParts[0] + cipheredParts[1] + cipheredParts[2] + cipheredParts[3];
char[] cipheredMsg = new char[cipheredString.Length * 2];
for (int i = 0; i < cipheredString.Length; i++)
{
cipheredMsg[i * 2] = randomKey[i];
cipheredMsg[(i * 2) + 1] = cipheredString[i];
}
return(new string(cipheredMsg));
}