org.bouncycastle.pqc.math.ntru.polynomial.DenseTernaryPolynomial Maven / Gradle / Ivy
package org.bouncycastle.pqc.math.ntru.polynomial;
import java.security.SecureRandom;
import org.bouncycastle.pqc.math.ntru.util.Util;
import org.bouncycastle.util.Arrays;
/**
* A TernaryPolynomial with a "high" number of nonzero coefficients.
*/
public class DenseTernaryPolynomial
extends IntegerPolynomial
implements TernaryPolynomial
{
/**
* Constructs a new DenseTernaryPolynomial with N coefficients.
*
* @param N the number of coefficients
*/
DenseTernaryPolynomial(int N)
{
super(N);
checkTernarity();
}
/**
* Constructs a DenseTernaryPolynomial from a IntegerPolynomial. The two polynomials are
* independent of each other.
*
* @param intPoly the original polynomial
*/
public DenseTernaryPolynomial(IntegerPolynomial intPoly)
{
this(intPoly.coeffs);
}
/**
* Constructs a new DenseTernaryPolynomial with a given set of coefficients.
*
* @param coeffs the coefficients
*/
public DenseTernaryPolynomial(int[] coeffs)
{
super(coeffs);
checkTernarity();
}
private void checkTernarity()
{
for (int i = 0; i != coeffs.length; i++)
{
int c = coeffs[i];
if (c < -1 || c > 1)
{
throw new IllegalStateException("Illegal value: " + c + ", must be one of {-1, 0, 1}");
}
}
}
/**
* Generates a random polynomial with numOnes coefficients equal to 1,
* numNegOnes coefficients equal to -1, and the rest equal to 0.
*
* @param N number of coefficients
* @param numOnes number of 1's
* @param numNegOnes number of -1's
*/
public static DenseTernaryPolynomial generateRandom(int N, int numOnes, int numNegOnes, SecureRandom random)
{
int[] coeffs = Util.generateRandomTernary(N, numOnes, numNegOnes, random);
return new DenseTernaryPolynomial(coeffs);
}
/**
* Generates a polynomial with coefficients randomly selected from {-1, 0, 1}.
*
* @param N number of coefficients
*/
public static DenseTernaryPolynomial generateRandom(int N, SecureRandom random)
{
DenseTernaryPolynomial poly = new DenseTernaryPolynomial(N);
for (int i = 0; i < N; i++)
{
poly.coeffs[i] = random.nextInt(3) - 1;
}
return poly;
}
public IntegerPolynomial mult(IntegerPolynomial poly2, int modulus)
{
// even on 32-bit systems, LongPolynomial5 multiplies faster than IntegerPolynomial
if (modulus == 2048)
{
IntegerPolynomial poly2Pos = (IntegerPolynomial)poly2.clone();
poly2Pos.modPositive(2048);
LongPolynomial5 poly5 = new LongPolynomial5(poly2Pos);
return poly5.mult(this).toIntegerPolynomial();
}
else
{
return super.mult(poly2, modulus);
}
}
public int[] getOnes()
{
int N = coeffs.length;
int[] ones = new int[N];
int onesIdx = 0;
for (int i = 0; i < N; i++)
{
int c = coeffs[i];
if (c == 1)
{
ones[onesIdx++] = i;
}
}
return Arrays.copyOf(ones, onesIdx);
}
public int[] getNegOnes()
{
int N = coeffs.length;
int[] negOnes = new int[N];
int negOnesIdx = 0;
for (int i = 0; i < N; i++)
{
int c = coeffs[i];
if (c == -1)
{
negOnes[negOnesIdx++] = i;
}
}
return Arrays.copyOf(negOnes, negOnesIdx);
}
public int size()
{
return coeffs.length;
}
}