private bool verify(IntegerPolynomial i, IntegerPolynomial s, IntegerPolynomial h)
{
int q = param.q;
double normBoundSq = param.normBoundSq;
double betaSq = param.betaSq;
IntegerPolynomial t = h.Multiply(s, q);
t.Subtract(i);
long centeredNormSq = (long)(s.CenteredNormSq(q) + betaSq * t.CenteredNormSq(q));
return(centeredNormSq <= normBoundSq);
}
private bool verify(IntegerPolynomial i, IntegerPolynomial s, IntegerPolynomial h)
{
int q = param.q;
double normBoundSq = param.normBoundSq;
double betaSq = param.betaSq;
IntegerPolynomial t = h.Multiply(s, q);
t.Subtract(i);
long centeredNormSq = (long)(s.CenteredNormSq(q) + betaSq * t.CenteredNormSq(q));
return centeredNormSq <= normBoundSq;
}
/**
* Returns <code>true</code> if the norms of the polynomials <code>F</code> and <code>G</code>
* are within {@link SignatureParameters#keyNormBound}.
* @return
*/
public bool isNormOk()
{
return(F.CenteredNormSq(q) < keyNormBoundSq && G.CenteredNormSq(q) < keyNormBoundSq);
}
/**
* Tests if the basis is valid.
* @param h the polynomial h (either from the public key or from this basis)
* @return <code>true</code> if the basis is valid, <code>false</code> otherwise
*/
public bool isValid(IntegerPolynomial h)
{
if (f.ToIntegerPolynomial().Coeffs.Length != N)
{
return(false);
}
if (fPrime.ToIntegerPolynomial().Coeffs.Length != N)
{
return(false);
}
if (h.Coeffs.Length != N || !h.IsReduced(q))
{
return(false);
}
// determine F, G, g from f, fPrime, h using the eqn. fG-Fg=q
IPolynomial FPoly = basisType == BasisType.STANDARD ? fPrime : f.Multiply(h, q);
IntegerPolynomial F = FPoly.ToIntegerPolynomial();
IntegerPolynomial fq = f.ToIntegerPolynomial().InvertFq(q);
IPolynomial g;
if (basisType == BasisType.STANDARD)
{
g = f.Multiply(h, q);
}
else
{
g = fPrime;
}
IntegerPolynomial G = g.Multiply(F);
G.Coeffs[0] -= q;
G = G.Multiply(fq, q);
G.ModCenter(q);
// check norms of F and G
if (!new FGBasis(f, fPrime, h, F, G, q, polyType, basisType, keyNormBoundSq).isNormOk())
{
return(false);
}
// check norms of f and g
int factor = N / 24;
if (f.ToIntegerPolynomial().CenteredNormSq(q) * factor >= F.CenteredNormSq(q))
{
return(false);
}
if (g.ToIntegerPolynomial().CenteredNormSq(q) * factor >= G.CenteredNormSq(q))
{
return(false);
}
// check ternarity
if (polyType == TernaryPolynomialType.SIMPLE)
{
if (!f.ToIntegerPolynomial().IsTernary())
{
return(false);
}
if (!g.ToIntegerPolynomial().IsTernary())
{
return(false);
}
}
else
{
if (!(f.GetType().IsAssignableFrom(typeof(ProductFormPolynomial))))
{
return(false);
}
if (!(g.GetType().IsAssignableFrom(typeof(ProductFormPolynomial))))
{
return(false);
}
}
return(true);
}
