public void TestRandomBigInteger()
{
var rnd = new Random();
var rng = new RNGCryptoServiceProvider();
for (var keySize = 384; keySize <= 1088; keySize += 8)
{
ElGamalModified algorithm = new ElGamalModifiedManaged
{
//Padding = ElGamalPaddingMode.BigIntegerPadding,
KeySize = keySize
};
ElGamalModified encryptAlgorithm = new ElGamalModifiedManaged();
encryptAlgorithm.FromXmlString(algorithm.ToXmlString(false));
ElGamalModified decryptAlgorithm = new ElGamalModifiedManaged();
decryptAlgorithm.FromXmlString(algorithm.ToXmlString(true));
var z = new BigInteger(); // Plaintext that is bigger than one block needs different padding,
// and the encryption loses homomorphic properties
z = z.GenRandomBits(rnd.Next(1, ((ElGamalModifiedManaged)algorithm).KeyStruct.getPlaintextBlocksize()), rng);
var z_enc_bytes = encryptAlgorithm.EncryptData(z);
var z_dec_bytes = decryptAlgorithm.DecryptData(z_enc_bytes);
Assert.True(z == z_dec_bytes, $"{Environment.NewLine}{Environment.NewLine}" +
$"Algorithm parameters (TRUE):{Environment.NewLine}" +
$"{algorithm.ToXmlString(true)}{Environment.NewLine}{Environment.NewLine}" +
$"Algorithm parameters (FALSE):{Environment.NewLine}" +
$"{algorithm.ToXmlString(false)}{Environment.NewLine}{Environment.NewLine}" +
$"z: {z}{Environment.NewLine}{Environment.NewLine}" +
$"z_dec: {z_dec_bytes}");
}
}
public void TestSpecificCases()
{
{
ElGamalModified algorithm = new ElGamalModifiedManaged
{
KeySize = 384,
//Padding = ElGamalPaddingMode.BigIntegerPadding
};
var a = new BigInteger(2048);
var a_bytes = algorithm.EncryptData(a);
var dec_a = algorithm.DecryptData(a_bytes);
Assert.Equal(a, dec_a);
}
{
ElGamalModified algorithm = new ElGamalModifiedManaged
{
KeySize = 384,
//Padding = ElGamalPaddingMode.BigIntegerPadding
};
var a = new BigInteger(138);
var a_bytes = algorithm.EncryptData(a);
var dec_a = algorithm.DecryptData(a_bytes);
Assert.Equal(a, dec_a);
}
}
public void TestMultiplication_Batch()
{
var iterations = 3;
var rnd = new Random();
for (var keySize = 384; keySize <= 1088; keySize += 8)
{
for (var i = 0; i < iterations; i++)
{
ElGamalModified algorithm = new ElGamalModifiedManaged
{
KeySize = keySize,
//Padding = ElGamalPaddingMode.BigIntegerPadding
};
ElGamalModified encryptAlgorithm = new ElGamalModifiedManaged();
encryptAlgorithm.FromXmlString(algorithm.ToXmlString(false));
ElGamalModified decryptAlgorithm = new ElGamalModifiedManaged();
decryptAlgorithm.FromXmlString(algorithm.ToXmlString(true));
var a = new BigInteger(rnd.Next());
var b = new BigInteger(rnd.Next());
var a_bytes = encryptAlgorithm.EncryptData(a);
var b_bytes = encryptAlgorithm.EncryptData(b);
var c_bytes = encryptAlgorithm.Multiply(a_bytes, b_bytes);
var dec_c = decryptAlgorithm.DecryptData(c_bytes);
var ab_result = a * b;
Assert.True(dec_c == ab_result, $"{Environment.NewLine}{Environment.NewLine}" +
$"Algorithm parameters (TRUE):{Environment.NewLine}" +
$"{algorithm.ToXmlString(true)}{Environment.NewLine}{Environment.NewLine}" +
$"Algorithm parameters (FALSE):{Environment.NewLine}" +
$"{algorithm.ToXmlString(false)}{Environment.NewLine}{Environment.NewLine}" +
$"a : {a}{Environment.NewLine}{Environment.NewLine}" +
$"b : {b}{Environment.NewLine}{Environment.NewLine}" +
$"a*b : {ab_result}{Environment.NewLine}{Environment.NewLine}" +
$"dec_c : {dec_c}");
}
}
}
public void Test_FromIssue_15() // based on https://github.com/bazzilic/PaillierExt/issues/15
{
for (var keySize = 384; keySize <= 1088; keySize += 8)
{
ElGamalModified algorithm = new ElGamalModifiedManaged
{
KeySize = keySize,
//Padding = ElGamalPaddingMode.BigIntegerPadding
};
var prod = algorithm.EncryptData(new BigInteger(1));
var three = algorithm.EncryptData(new BigInteger(3));
for (var i = 0; i < 30; i++)
{
prod = algorithm.Multiply(prod, three);
}
var sum_dec = algorithm.DecryptData(prod);
Assert.Equal(new BigInteger(205891132094649), sum_dec);
}
}
