public static BigRational ComputeP(int k, int n, int p)
{
// the P(n) equation
BigRational pnNumerator = BigRational.Pow(p, n);
BigRational pnDenominator = BigRational.Pow(k, (n - k)) * Factorial(k);
// the P(0) equation
//---the right side of "+" sign in Denominator
BigRational pk = BigRational.Pow(p, k);
BigRational factorialK = Factorial(k);
// CHANGED: Don't cast to double here (loses precision)
BigRational lastPart = (BigRational.Subtract(1, BigRational.Divide(p, k)));
BigRational factorialAndLastPart = BigRational.Multiply(factorialK, lastPart);
BigRational fullRightSide = BigRational.Divide(pk, factorialAndLastPart);
//---the left side of "+" sign in Denominator
BigRational series = Series(k, p);
BigRational p0Denominator = series + fullRightSide;
BigRational p0Result = BigRational.Divide(1, p0Denominator);
BigRational pNResult = BigRational.Divide((pnNumerator * p0Result), pnDenominator);
return(pNResult);
}
public void TestMultiplication()
{
BigRational sevenTwoths = new BigRational(BigInteger.Zero, new Fraction(7, 2));
BigRational sevenFifths = new BigRational(BigInteger.Zero, new Fraction(7, 5));
BigRational expected = BigRational.Reduce(new BigRational(BigInteger.Zero, 49, 10));
BigRational result = BigRational.Multiply(sevenTwoths, sevenFifths);
Assert.AreEqual(expected, result);
}
public static BigRational Factorial(int k)
{
if (k <= 1)
{
return(1);
}
else
{
return(BigRational.Multiply(k, Factorial(k - 1)));
}
}
public override byte[] Split(byte[] secretClear, int shareCount, int threshold)
{
// var primeArr = ComputeRandomePrime();
// var prime = new BigInteger(primeArr);
var primeMinusOne = _prime - 1;
var number = new BigInteger(secretClear);
var coef = new BigInteger[threshold];
coef[0] = number;
// TODO: rewrite this to use cryptographically-secure RNG
var rng = new Random();
var pmo = new BigRational(primeMinusOne);
for (int c = 1; c < threshold; ++c)
{
coef[c] = BigRational.Multiply(pmo, new BigRational(rng.NextDouble())).GetWholePart();
}
var shares = new Tuple <int, BigInteger> [shareCount];
for (var x = 1; x <= shareCount; ++x)
{
System.Console.WriteLine("X: " + x);
var accum = coef[0];
for (int exp = 1; exp < threshold; ++exp)
{
// accum = (accum + (coef[exp] * (Math.pow(x, exp) % prime) % prime)) % prime;
var a = new BigInteger(Math.Pow(x, exp)) % _prime; // (Math.pow(x, exp) % prime)
var b = (coef[exp] * a) % _prime; // (coef[exp] * a % prime)
var c = (accum + b) % _prime; // (accum + b) % prime;
accum = c;
}
shares[x - 1] = Tuple.Create(x, accum);
}
Shares = shares.Select(x => {
var index = BitConverter.GetBytes(x.Item1);
var biarr = x.Item2.ToByteArray();
var bytes = new byte[INT_ARR_LEN + biarr.Length];
Array.Copy(index, 0, bytes, 0, INT_ARR_LEN);
Array.Copy(biarr, 0, bytes, INT_ARR_LEN, biarr.Length);
return(bytes);
});
// The original secret value is fully encoded in the distributed shares so there
// is no need to return any version of the original secreted in encrypted form
return(new byte[0]);
}
public void big_rational_static_methods()
{
Assert.True(0.5 == BigRational.Abs(0.5d));
Assert.True(0.5 == BigRational.Abs(-0.5d));
Assert.False(0.5 == BigRational.Abs(-1));
Assert.False(0.5 == BigRational.Abs(1));
Assert.True(-0.5 == BigRational.Negate(0.5d));
Assert.True(0.5 == BigRational.Negate(-0.5d));
Assert.False(0.5 == BigRational.Negate(-1));
Assert.False(-0.5 == BigRational.Negate(1));
//Doesn't work great... testing with equals doubles fails
Assert.True(new BigRational(1, 2) == BigRational.Invert(new BigRational(2, 1)));
Assert.True(new BigRational(2, 1) == BigRational.Invert(new BigRational(1, 2)));
Assert.True(new BigRational(-1, 2) == BigRational.Invert(new BigRational(-2, 1)));
Assert.True(new BigRational(-2, 1) == BigRational.Invert(new BigRational(-1, 2)));
Assert.True(new BigRational(BigInteger.One) + new BigRational(BigInteger.One) == 2);
Assert.True(BigRational.Add(new BigRational(BigInteger.One), new BigRational(BigInteger.One)) == 2);
//Not working for me
//BigRational big1 = new BigRational(1.0);
//big1++;
//Assert.AreEqual(new BigRational(2, 1), big1);
//Not working for me
//BigRational big2 = new BigRational(1.0);
//big2--;
//Assert.True(0 == big2);
Assert.True(new BigRational(BigInteger.One) - new BigRational(BigInteger.One) == 0);
Assert.True(BigRational.Subtract(new BigRational(BigInteger.One), new BigRational(BigInteger.One)) == 0);
BigRational big3 = new BigRational(1.0);
Assert.True(-1.0 == -big3);
BigRational big4 = new BigRational(1.0);
Assert.True(1.0 == +big3);
Assert.True(new BigRational(BigInteger.One) * new BigRational(BigInteger.One) == 1);
Assert.True(BigRational.Multiply(new BigRational(BigInteger.One), new BigRational(BigInteger.One)) == 1);
Assert.True(new BigRational(BigInteger.One) * new BigRational(2.0) == 2.0);
Assert.True(BigRational.Multiply(new BigRational(BigInteger.One), new BigRational(2.0)) == 2.0);
Assert.True(new BigRational(BigInteger.One) / new BigRational(BigInteger.One) == 1);
Assert.True(BigRational.Divide(new BigRational(BigInteger.One), new BigRational(BigInteger.One)) == 1);
Assert.AreEqual(new BigRational(1, 2), new BigRational(new BigInteger(1)) / new BigRational(new BigInteger(2))); //Again, mixing consructors doesn't work well.
Assert.AreEqual(new BigRational(1, 2), BigRational.Divide(new BigRational(new BigInteger(1)), new BigRational(new BigInteger(2)))); //Again, mixing consructors doesn't work well. Testing with equals double 0.5 fails
//Assert.True(new BigRational(BigInteger.One) < new BigRational(2.0)); //Don't mix the constructors for comparison!!!
Assert.True(new BigRational(1.0) < new BigRational(2.0));
Assert.False(new BigRational(2.0) < new BigRational(1.0));
Assert.False(new BigRational(1.0) < new BigRational(1.0));
Assert.True(new BigRational(1.0) <= new BigRational(2.0));
Assert.True(new BigRational(1.0) <= new BigRational(1.0));
Assert.False(new BigRational(2.0) <= new BigRational(1.0));
Assert.True(new BigRational(1.0) == new BigRational(1.0));
Assert.True(new BigRational(1.0) != new BigRational(2.0));
Assert.False(new BigRational(1.0) > new BigRational(2.0));
Assert.True(new BigRational(2.0) > new BigRational(1.0));
Assert.False(new BigRational(BigInteger.One) > new BigRational(BigInteger.One));
Assert.False(new BigRational(1.0) >= new BigRational(2.0));
Assert.True(new BigRational(BigInteger.One) >= new BigRational(BigInteger.One));
Assert.True(new BigRational(2.0) >= new BigRational(1.0));
//Modulus doesn't seem to work well
//Assert.AreEqual(BigRational.Zero, new BigRational(2.0) % new BigRational(1.0));
//Assert.AreEqual(BigRational.One, new BigRational(3.0) % new BigRational(2.0));
//Assert.True(new BigRational(1.5) % new BigRational(1.0) == new BigRational(0.5));
//Assert.True(new BigRational(1.0) % new BigRational(2.0) == 0);
}
