public static SplitSecret Split(SecretShareType shareType, byte[] secret, int threshold, Diffuser diffuser)
{
var irreduciblePolynomial = IrreduciblePolynomial.CreateOfByteSize(secret.Length);
var rawSecret = secret.ToBigIntegerFromBigEndianUnsignedBytes();
var diffusedSecret = diffuser.Scramble(rawSecret, secret.Length);
var secretCoefficient = new FiniteFieldPolynomial(irreduciblePolynomial, diffusedSecret);
var allCoefficients = new[] { secretCoefficient }
.Concat(
GetRandomPolynomials(
irreduciblePolynomial,
threshold - 1)
)
.ToArray();
var passPhrase = new SecureString();
try {
foreach (var currentChar in secret.ToHexString())
{
passPhrase.AppendChar(currentChar);
}
}
catch {
passPhrase = null;
}
if ((passPhrase == null) || (passPhrase.Length == 0))
{
passPhrase = null;
}
return(new SplitSecret(shareType, threshold, irreduciblePolynomial, allCoefficients, passPhrase));
}
public SecretShare GetShare(int n)
{
var xPoly = new FiniteFieldPolynomial(_IrreduciblePolynomial, new BigInteger(n));
var y = FiniteFieldPolynomial.EvaluateAt(n, _AllCoefficients);
return(new SecretShare(_ShareType, new FiniteFieldPoint(xPoly, y)));
}
public void BasicTests()
{
var rijndaelPoly = new IrreduciblePolynomial(8);
var a = new FiniteFieldPolynomial(rijndaelPoly, 6, 4, 1, 0);
var b = new FiniteFieldPolynomial(rijndaelPoly, 7, 6, 3, 1);
var product = a * b;
// "a" and "b" are inverses, so their product is 1
Assert.AreEqual(1, (int)product.PolynomialValue);
var g = new FiniteFieldPolynomial(rijndaelPoly, BigInteger.Parse("0e5", NumberStyles.HexNumber));
var p = new FiniteFieldPolynomial(rijndaelPoly, BigInteger.One);
// g is a generator, so we should generate all values except 0
var vals = new HashSet <BigInteger> {
p.PolynomialValue
};
for (int i = 0; i < 255; i++)
{
p = p * g;
vals.Add(p.PolynomialValue);
}
Assert.AreEqual(255, vals.Count);
Assert.IsTrue(vals.Contains((p * g).PolynomialValue));
}
public void TestInverse()
{
var rijndaelPoly = new IrreduciblePolynomial(8);
var a = new FiniteFieldPolynomial(rijndaelPoly, 6, 4, 1, 0);
var expectedInverse = new FiniteFieldPolynomial(rijndaelPoly, 7, 6, 3, 1);
var actualInverse = a.GetInverse();
Assert.AreEqual(expectedInverse.ToString(), actualInverse.ToString());
var productSanityCheck = a * actualInverse;
Assert.IsTrue(productSanityCheck.One.Equals(productSanityCheck));
}
public static SplitSecret Split(byte[] secret, int threshold)
{
var irreduciblePolynomial = IrreduciblePolynomial.CreateOfByteSize(secret.Length);
var rawSecret = secret.ToBigIntegerFromBigEndianUnsignedBytes();
var diffusedSecret = DefaultDiffuser.Scramble(rawSecret, secret.Length);
var secretCoefficient = new FiniteFieldPolynomial(irreduciblePolynomial, diffusedSecret);
var allCoefficients = new[] { secretCoefficient }
.Concat(
GetRandomPolynomials(
irreduciblePolynomial,
threshold - 1)
)
.ToArray();
return(new SplitSecret(threshold, irreduciblePolynomial, allCoefficients));
}
