public void ShouldCeilingDivideCorrectly(BigInteger a, BigInteger b, BigInteger expectedResult)
{
Assert.AreEqual(expectedResult, a.CeilingDivide(b));
}
/// <summary>
/// A.1.2.1.2
/// </summary>
/// <param name="L"></param>
/// <param name="N"></param>
/// <param name="firstSeed"></param>
/// <returns></returns>
private PQGenerateResult Generate(int L, int N, BigInteger firstSeed)
{
// 1
if (!DSAHelper.VerifyLenPair(L, N))
{
return(new PQGenerateResult("Bad L, N pair"));
}
// 2
var qResult = PrimeGen186_4.ShaweTaylorRandomPrime(N, firstSeed, _sha);
if (!qResult.Success)
{
return(new PQGenerateResult("Failed to generate q from ShaweTaylor"));
}
var q = qResult.Prime;
var qSeed = qResult.PrimeSeed;
var qCounter = qResult.PrimeGenCounter;
// 3
var pLen = L.CeilingDivide(2) + 1;
var pResult = PrimeGen186_4.ShaweTaylorRandomPrime(pLen, qSeed, _sha);
if (!pResult.Success)
{
return(new PQGenerateResult("Failed to generate p0 from ShaweTaylor"));
}
var p0 = pResult.Prime;
var pSeed = pResult.PrimeSeed;
var pCounter = pResult.PrimeGenCounter;
// 4, 5
var outLen = _sha.HashFunction.OutputLen;
var iterations = L.CeilingDivide(outLen) - 1;
var oldCounter = pCounter;
// 6, 7
BigInteger x = 0;
for (var i = 0; i <= iterations; i++)
{
x += _sha.HashNumber(pSeed + i).ToBigInteger() * NumberTheory.Pow2(i * outLen);
}
// 8
pSeed += iterations + 1;
// 9
x = NumberTheory.Pow2(L - 1) + (x % NumberTheory.Pow2(L - 1));
// 10
var t = x.CeilingDivide(2 * q * p0);
do
{
// 11
if (2 * t * q * p0 + 1 > NumberTheory.Pow2(L))
{
t = NumberTheory.Pow2(L - 1).CeilingDivide(2 * q * p0);
}
// 12, 13
var p = 2 * t * q * p0 + 1;
pCounter++;
// 14, 15
BigInteger a = 0;
for (var i = 0; i <= iterations; i++)
{
a += _sha.HashNumber(pSeed + i).ToBigInteger() * NumberTheory.Pow2(i * outLen);
}
// 16
pSeed += iterations + 1;
// 17
a = 2 + (a % (p - 3));
// 18
var z = BigInteger.ModPow(a, 2 * t * q, p);
// 19
if (1 == NumberTheory.GCD(z - 1, p) && 1 == BigInteger.ModPow(z, p0, p))
{
return(new PQGenerateResult(p, q, new DomainSeed(firstSeed, pSeed, qSeed), new Counter(pCounter, qCounter)));
}
// 20
if (pCounter > 4 * L + oldCounter)
{
return(new PQGenerateResult("Too many iterations"));
}
// 21
t++;
// 22
} while (true);
}
