public void RunTest()
{
// Done by sender
//BigInteger p = 2357;
BigInteger p = this.GenerateP(32);
//BigInteger alpha = 2;
BigInteger alpha = Helpers.GetRandomBigInteger(1, p - 1);
//BigInteger a = 1751;
BigInteger a = Helpers.GetRandomBigInteger(1, p - 2);
BigInteger alphaToA = Helpers.SquareAndMultiply(alpha, a, p);
ElGamalPublicKey publicKey = new ElGamalPublicKey(p, alpha, alphaToA);
ElGamalPrivateKey privateKey = new ElGamalPrivateKey(a);
// Done by receiver
int message = 2035;
//BigInteger k = 1520; // Random number 1 <= k <= p-2
BigInteger k = Helpers.GetRandomBigInteger(1, p - 2); // Random number 1 <= k <= p-2
BigInteger gamma = Helpers.SquareAndMultiply(alpha, k, p);
BigInteger delta = (message * Helpers.SquareAndMultiply(publicKey.AlphaToA, k, p)) % p;
Tuple <BigInteger, BigInteger> cipherText = new Tuple <BigInteger, BigInteger>(gamma, delta);
// Done by receiver
BigInteger gammaToTheNegativeA = Helpers.SquareAndMultiply(gamma, (p - 1 - a), p);
BigInteger plainText = gammaToTheNegativeA * delta % p;
Console.WriteLine("plainText: " + message);
Console.WriteLine("cipherText: (" + gamma + "," + delta + ")");
Console.WriteLine("plainText: " + plainText);
}
public Tuple <BigInteger, BigInteger> Encrypt(string plainText, ElGamalPublicKey publicKey)
{
byte[] plainTextAsBytes = Encoding.UTF8.GetBytes(plainText);
BigInteger plainTextAsNumber = new BigInteger(plainTextAsBytes);
if (plainTextAsNumber > publicKey.P)
{
throw new Exception("The Master Key cannot exceed n");
}
BigInteger k = Helpers.GetRandomBigInteger(1, publicKey.P - 2);
BigInteger gamma = Helpers.SquareAndMultiply(publicKey.Alpha, k, publicKey.P);
BigInteger delta = (plainTextAsNumber * Helpers.SquareAndMultiply(publicKey.AlphaToA, k, publicKey.P)) % publicKey.P;
Tuple <BigInteger, BigInteger> cipherText = new Tuple <BigInteger, BigInteger>(gamma, delta);
return(cipherText);
}
public List <Tuple <BigInteger, BigInteger> > EncryptWithChunking(string plainText, ElGamalPublicKey publicKey)
{
List <string> plainTextChunks = new List <string>();
chunkIfRequired(plainText, publicKey.P, plainTextChunks);
List <Tuple <BigInteger, BigInteger> > encryptedChunks = new List <Tuple <BigInteger, BigInteger> >();
BigInteger k = Helpers.GetRandomBigInteger(1, publicKey.P - 2);
BigInteger gamma = Helpers.SquareAndMultiply(publicKey.Alpha, k, publicKey.P);
foreach (string chunk in plainTextChunks)
{
byte[] chunkAsBytes = Encoding.UTF8.GetBytes(chunk);
BigInteger chunkAsNumber = new BigInteger(chunkAsBytes);
BigInteger delta = (chunkAsNumber * Helpers.SquareAndMultiply(publicKey.AlphaToA, k, publicKey.P)) % publicKey.P;
Tuple <BigInteger, BigInteger> encryptedChunk = new Tuple <BigInteger, BigInteger>(gamma, delta);
encryptedChunks.Add(encryptedChunk);
}
return(encryptedChunks);
}