org.bouncycastle.pqc.math.ntru.polynomial
Class SparseTernaryPolynomial

java.lang.Object
  org.bouncycastle.pqc.math.ntru.polynomial.SparseTernaryPolynomial

All Implemented Interfaces:

Polynomial, TernaryPolynomial

public class SparseTernaryPolynomial
extends java.lang.Object
implements TernaryPolynomial

A TernaryPolynomial with a "low" number of nonzero coefficients.

Constructor Summary

SparseTernaryPolynomial(int[] coeffs)
Constructs a new SparseTernaryPolynomial with a given set of coefficients.

SparseTernaryPolynomial(IntegerPolynomial intPoly)
Constructs a DenseTernaryPolynomial from a IntegerPolynomial.

Method Summary

void	clear()
boolean	equals(java.lang.Object obj)
static SparseTernaryPolynomial	fromBinary(java.io.InputStream is, int N, int numOnes, int numNegOnes) Decodes a byte array encoded with toBinary() to a ploynomial.
static SparseTernaryPolynomial	generateRandom(int N, int numOnes, int numNegOnes, java.security.SecureRandom random) Generates a random polynomial with numOnes coefficients equal to 1, numNegOnes coefficients equal to -1, and the rest equal to 0.
int[]	getNegOnes()
int[]	getOnes()
int	hashCode()
BigIntPolynomial	mult(BigIntPolynomial poly2) Multiplies the polynomial by a BigIntPolynomial, taking the indices mod N.
IntegerPolynomial	mult(IntegerPolynomial poly2) Multiplies the polynomial by an IntegerPolynomial, taking the indices mod N
IntegerPolynomial	mult(IntegerPolynomial poly2, int modulus) Multiplies the polynomial by an IntegerPolynomial, taking the coefficient values mod modulus and the indices mod N.
int	size() Returns the maximum number of coefficients the polynomial can have
byte[]	toBinary() Encodes the polynomial to a byte array writing BITS_PER_INDEX bits for each coefficient.
IntegerPolynomial	toIntegerPolynomial() Returns a polynomial that is equal to this polynomial (in the sense that Polynomial.mult(IntegerPolynomial, int) returns equal IntegerPolynomials).

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SparseTernaryPolynomial

public SparseTernaryPolynomial(IntegerPolynomial intPoly)

Constructs a DenseTernaryPolynomial from a IntegerPolynomial. The two polynomials are independent of each other.

Parameters:

intPoly - the original polynomial

SparseTernaryPolynomial

public SparseTernaryPolynomial(int[] coeffs)

Constructs a new SparseTernaryPolynomial with a given set of coefficients.

Parameters:

coeffs - the coefficients

Method Detail

fromBinary

public static SparseTernaryPolynomial fromBinary(java.io.InputStream is,
                                                 int N,
                                                 int numOnes,
                                                 int numNegOnes)
                                          throws java.io.IOException

Decodes a byte array encoded with toBinary() to a ploynomial.

Parameters:

is - an input stream containing an encoded polynomial

N - number of coefficients including zeros

numOnes - number of coefficients equal to 1

numNegOnes - number of coefficients equal to -1

Returns:

the decoded polynomial

Throws:

java.io.IOException

generateRandom

public static SparseTernaryPolynomial generateRandom(int N,
                                                     int numOnes,
                                                     int numNegOnes,
                                                     java.security.SecureRandom random)

Generates a random polynomial with numOnes coefficients equal to 1, numNegOnes coefficients equal to -1, and the rest equal to 0.

Parameters:

N - number of coefficients

numOnes - number of 1's

numNegOnes - number of -1's

mult

public IntegerPolynomial mult(IntegerPolynomial poly2)

Description copied from interface: TernaryPolynomial

Multiplies the polynomial by an IntegerPolynomial, taking the indices mod N

Specified by:

mult in interface Polynomial

Specified by:

mult in interface TernaryPolynomial

Parameters:

poly2 - a polynomial

Returns:

the product of the two polynomials

mult

public IntegerPolynomial mult(IntegerPolynomial poly2,
                              int modulus)

Description copied from interface: Polynomial

Multiplies the polynomial by an IntegerPolynomial, taking the coefficient values mod modulus and the indices mod N.

Specified by:

mult in interface Polynomial

Parameters:

poly2 - a polynomial

modulus - a modulus to apply

Returns:

the product of the two polynomials

mult

public BigIntPolynomial mult(BigIntPolynomial poly2)

Description copied from interface: Polynomial

Multiplies the polynomial by a BigIntPolynomial, taking the indices mod N. Does not change this polynomial but returns the result as a new polynomial.
Both polynomials must have the same number of coefficients.

Specified by:

mult in interface Polynomial

Parameters:

poly2 - the polynomial to multiply by

Returns:

a new polynomial

getOnes

public int[] getOnes()

Specified by:

getOnes in interface TernaryPolynomial

getNegOnes

public int[] getNegOnes()

Specified by:

getNegOnes in interface TernaryPolynomial

toBinary

public byte[] toBinary()

Encodes the polynomial to a byte array writing BITS_PER_INDEX bits for each coefficient.

Returns:

the encoded polynomial

toIntegerPolynomial

public IntegerPolynomial toIntegerPolynomial()

Description copied from interface: Polynomial

Returns a polynomial that is equal to this polynomial (in the sense that Polynomial.mult(IntegerPolynomial, int) returns equal IntegerPolynomials). The new polynomial is guaranteed to be independent of the original.

Specified by:

toIntegerPolynomial in interface Polynomial

Returns:

a new IntegerPolynomial.

size

public int size()

Description copied from interface: TernaryPolynomial

Returns the maximum number of coefficients the polynomial can have

Specified by:

size in interface TernaryPolynomial

clear

public void clear()

Specified by:

clear in interface TernaryPolynomial

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(java.lang.Object obj)

Overrides:

equals in class java.lang.Object