public void testMult()
{
BigDecimalPolynomial a = new BigDecimalPolynomial(new BigIntPolynomial(new IntegerPolynomial(new int[] { 4, -1, 9, 2, 1, -5, 12, -7, 0, -9, 5 })));
BigDecimalPolynomial b = new BigDecimalPolynomial(new BigIntPolynomial(new IntegerPolynomial(new int[] { -6, 0, 0, 13, 3, -2, -4, 10, 11, 2, -1 })));
BigDecimalPolynomial c = a.Multiply(b);
decimal[] expectedCoeffs = new BigDecimalPolynomial(new BigIntPolynomial(new IntegerPolynomial(new int[] { 2, -189, 77, 124, -29, 0, -75, 124, -49, 267, 34 }))).getCoeffs();
decimal[] cCoeffs = c.getCoeffs();
Assert.AreEqual(expectedCoeffs.Length, cCoeffs.Length);
for (int i = 0; i != cCoeffs.Length; i++)
{
Assert.AreEqual(expectedCoeffs[i], cCoeffs[i]);
}
// multiply a polynomial by its inverse modulo 2048 and check that the result is 1
SecureRandom random = new SecureRandom();
IntegerPolynomial d, dInv;
do
{
d = DenseTernaryPolynomial.GenerateRandom(1001, 333, 334, random);
dInv = d.InvertFq(2048);
}while (dInv == null);
d.Mod(2048);
BigDecimalPolynomial e = new BigDecimalPolynomial(new BigIntPolynomial(d));
BigIntPolynomial f = new BigIntPolynomial(dInv);
IntegerPolynomial g = new IntegerPolynomial(e.Multiply(f).round());
g.ModPositive(2048);
Assert.True(g.EqualsOne());
}
private BigDecimalPolynomial CreateBigDecimalPolynomial(int[] coeffs)
{
int N = coeffs.Length;
BigDecimalPolynomial poly = new BigDecimalPolynomial(N);
for (int i = 0; i < N; i++)
{
poly.Coeffs[i] = new BigDecimal(coeffs[i]);
}
return(poly);
}
/// <summary>
/// Test the validity of the BigDecimalPolynomial implementation
/// </summary>
///
/// <returns>State</returns>
public string Test()
{
try
{
BigDecimalPolynomial a = CreateBigDecimalPolynomial(new int[] { 4, -1, 9, 2, 1, -5, 12, -7, 0, -9, 5 });
BigIntPolynomial b = new BigIntPolynomial(new IntegerPolynomial(new int[] { -6, 0, 0, 13, 3, -2, -4, 10, 11, 2, -1 }));
BigDecimalPolynomial c = a.Multiply(b);
if (!Compare.AreEqual(c.Coeffs, CreateBigDecimalPolynomial(new int[] { 2, -189, 77, 124, -29, 0, -75, 124, -49, 267, 34 }).Coeffs))
{
throw new Exception("The BigDecimalPolynomial test failed!");
}
// multiply a polynomial by its inverse modulo 2048 and check that the result is 1
IntegerPolynomial d, dInv;
CSPRng rng = new CSPRng();
do
{
d = DenseTernaryPolynomial.GenerateRandom(1001, 333, 334, rng);
dInv = d.InvertFq(2048);
} while (dInv == null);
d.Mod(2048);
BigDecimalPolynomial e = CreateBigDecimalPolynomial(d.Coeffs);
BigIntPolynomial f = new BigIntPolynomial(dInv);
IntegerPolynomial g = new IntegerPolynomial(e.Multiply(f).Round());
g.ModPositive(2048);
if (!g.EqualsOne())
{
throw new Exception("The BigDecimalPolynomial test failed!");
}
OnProgress(new TestEventArgs("Passed BigDecimalPolynomial tests"));
return(SUCCESS);
}
catch (Exception Ex)
{
string message = Ex.Message == null ? "" : Ex.Message;
throw new Exception(FAILURE + message);
}
}
/**
* Creates a NtruSign basis consisting of polynomials <code>f, g, F, G, h</code>.<br/>
* If <code>KeyGenAlg=FLOAT</code>, the basis may not be valid and this method must be rerun if that is the case.<br/>
* @see #generateBoundedBasis()
*/
private FGBasis generateBasis()
{
int N = param.N;
int q = param.q;
int d = param.d;
int d1 = param.d1;
int d2 = param.d2;
int d3 = param.d3;
BasisType basisType = param.basisType;
IPolynomial f;
IntegerPolynomial fInt;
IPolynomial g;
IntegerPolynomial gInt;
IntegerPolynomial fq;
Resultant rf;
Resultant rg;
BigIntEuclidean r;
int _2n1 = 2 * N + 1;
bool primeCheck = param.primeCheck;
Random rng = new Random();
do
{
do
{
if (param.polyType == TernaryPolynomialType.SIMPLE)
{
f = DenseTernaryPolynomial.GenerateRandom(N, d + 1, d);
}
else
{
f = ProductFormPolynomial.GenerateRandom(N, d1, d2, d3 + 1, d3);
}
fInt = f.ToIntegerPolynomial();
} while (primeCheck && fInt.Resultant(_2n1).Res.Equals(BigInteger.Zero));
fq = fInt.InvertFq(q);
} while (fq == null);
rf = fInt.Resultant();
do
{
do
{
do
{
if (param.polyType == TernaryPolynomialType.SIMPLE)
{
g = DenseTernaryPolynomial.GenerateRandom(N, d + 1, d);
}
else
{
g = ProductFormPolynomial.GenerateRandom(N, d1, d2, d3 + 1, d3);
}
gInt = g.ToIntegerPolynomial();
} while (primeCheck && gInt.Resultant(_2n1).Res.Equals(BigInteger.Zero));
} while (!gInt.IsInvertiblePow2());
rg = gInt.Resultant();
r = BigIntEuclidean.Calculate(rf.Res, rg.Res);
} while (!r.GCD.Equals(BigInteger.One));
BigIntPolynomial A = rf.Rho.Clone();
A.Multiply(r.X.Multiply(BigInteger.ValueOf(q)));
BigIntPolynomial B = rg.Rho.Clone();
B.Multiply(r.Y.Multiply(BigInteger.ValueOf(-q)));
BigIntPolynomial C;
if (param.keyGenAlg == KeyGenAlg.RESULTANT)
{
int[] fRevCoeffs = new int[N];
int[] gRevCoeffs = new int[N];
fRevCoeffs[0] = fInt.Coeffs[0];
gRevCoeffs[0] = gInt.Coeffs[0];
for (int i = 1; i < N; i++)
{
fRevCoeffs[i] = fInt.Coeffs[N - i];
gRevCoeffs[i] = gInt.Coeffs[N - i];
}
IntegerPolynomial fRev = new IntegerPolynomial(fRevCoeffs);
IntegerPolynomial gRev = new IntegerPolynomial(gRevCoeffs);
IntegerPolynomial t = f.Multiply(fRev);
t.Add(g.Multiply(gRev));
Resultant rt = t.Resultant();
C = fRev.Multiply(B); // fRev.mult(B) is actually faster than new SparseTernaryPolynomial(fRev).mult(B), possibly due to cache locality?
C.Add(gRev.Multiply(A));
C = C.MultBig(rt.Rho);
C.Divide(rt.Res);
}
else // KeyGenAlg.FLOAT
// calculate ceil(log10(N))
{
int log10N = 0;
for (int i = 1; i < N; i *= 10)
{
log10N++;
}
// * Cdec needs to be accurate to 1 decimal place so it can be correctly rounded;
// * fInv loses up to (#digits of longest coeff of B) places in fInv.mult(B);
// * multiplying fInv by B also multiplies the rounding error by a factor of N;
// so make #decimal places of fInv the sum of the above.
BigDecimalPolynomial fInv = rf.Rho.Divide(new BigDecimal(rf.Res), B.GetMaxCoeffLength() + 1 + log10N);
BigDecimalPolynomial gInv = rg.Rho.Divide(new BigDecimal(rg.Res), A.GetMaxCoeffLength() + 1 + log10N);
BigDecimalPolynomial Cdec = fInv.Multiply(B);
Cdec.Add(gInv.Multiply(A));
Cdec.Halve();
C = Cdec.Round();
}
BigIntPolynomial F = B.Clone();
F.Subtract(f.Multiply(C));
BigIntPolynomial G = A.Clone();
G.Subtract(g.Multiply(C));
IntegerPolynomial FInt = new IntegerPolynomial(F);
IntegerPolynomial GInt = new IntegerPolynomial(G);
minimizeFG(fInt, gInt, FInt, GInt, N);
IPolynomial fPrime;
IntegerPolynomial h;
if (basisType == BasisType.STANDARD)
{
fPrime = FInt;
h = g.Multiply(fq, q);
}
else
{
fPrime = g;
h = FInt.Multiply(fq, q);
}
h.ModPositive(q);
return(new FGBasis(f, fPrime, h, FInt, GInt, param.q, param.polyType, param.basisType, param.keyNormBoundSq));
}
