public static string DecryptPolynomialBlockCipher(List <List <double> > coeffs, int key, int blockSize = 2)
{
string plainText = "";
if (key.IsEven())
{
key++;
}
foreach (var coeff in coeffs)
{
string cipherPart = PolynomialCipher.DecodePolynomial(coeff, key);
plainText += cipherPart.Replace("Z", " ").Replace("X", "-").Replace("Q", ".");
}
return(plainText);
}
public static string EncryptPolynomialBlockCipher(string plainText, int key, int blockSize = 2)
{
string cipherText = "";
// Even keys prevent the characters from being decrypted in the proper order
if (key.IsEven())
{
key++;
}
foreach (var raw in Common.SplitIntoNGrams(plainText, blockSize))
{
string ngram = raw.Replace(" ", "Z").Replace("-", "X").Replace(".", "Q");
cipherText += PolynomialCipher.CoeffsToPolynomial(PolynomialCipher.EncryptString(ngram, key)) + "\r\n";
}
return(cipherText);
}
