de.flexiprovider.common.math.polynomials
Class BinaryConvolutionPolynomial

java.lang.Object
  |
  +--de.flexiprovider.common.math.polynomials.BinaryConvolutionPolynomial

All Implemented Interfaces:

ConvolutionPolynomial

public class BinaryConvolutionPolynomial

extends java.lang.Object

implements ConvolutionPolynomial

This class represents binary polynomials in the ring Z(X)/(X^N-1). The coefficients of the polynomials are stored as compressed int arrays (32 coefficients per int).

Author:

Martin Döring

Field Summary

(package private) int[]	coefficients The coefficient array
(package private) int	degree The degree of this polynomial
(package private) int	N The degree of the reduction polynomial

Constructor Summary

BinaryConvolutionPolynomial(BinaryConvolutionPolynomial other)
Copy constructor.

BinaryConvolutionPolynomial(int N, int[] coefficients)
Create a binary polynomial out of the given coefficient array

BinaryConvolutionPolynomial(int N, int d, SecureRandom sr)
Create a binary polynomial of degree less than N.

Method Summary

boolean	equals(java.lang.Object other) Compare this binary polynomial with the given object.
(package private) int[][]	getPatternLocations(int w) Compute an array of bit pattern locations given a windows size according to Algorithm 2 of M.-K.
int	hashCode()
(package private) int	numCoeffs() Compute the number of 1 coefficients of this binary polynomial.
void	setCoefficient(int index) Set the coefficient with the given index.
boolean	testCoefficient(int index) Test whether the coefficient with the given index is 1.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

N

int N

The degree of the reduction polynomial

degree

int degree

The degree of this polynomial

coefficients

int[] coefficients

The coefficient array

Constructor Detail

BinaryConvolutionPolynomial

public BinaryConvolutionPolynomial(int N,
                                   int[] coefficients)
                            throws java.lang.IllegalArgumentException

Create a binary polynomial out of the given coefficient array

Parameters:

N - the degree of the reduction polynomial

coefficients - the coefficient array

Throws:

java.lang.IllegalArgumentException - if the degree of the given coefficient array is >= N.

BinaryConvolutionPolynomial

public BinaryConvolutionPolynomial(int N,
                                   int d,
                                   SecureRandom sr)

Create a binary polynomial of degree less than N.

Parameters:

N - the degree of the reduction polynomial

d - the number of non-zero coefficients

sr - source of randomness to create the polynomial

BinaryConvolutionPolynomial

public BinaryConvolutionPolynomial(BinaryConvolutionPolynomial other)

Copy constructor.

Parameters:

other - another BinaryPolynomial

Method Detail

setCoefficient

public void setCoefficient(int index)

Set the coefficient with the given index. If the index is out of bounds, do nothing.

Parameters:

index - the index

testCoefficient

public boolean testCoefficient(int index)

Test whether the coefficient with the given index is 1. If the index if out of bounds, return false.

Parameters:

index - the index of the coefficient to test

Returns:

true if the coefficient with the given index is 1, false otherwise or if the index is out of bounds

getPatternLocations

int[][] getPatternLocations(int w)

Compute an array of bit pattern locations given a windows size according to Algorithm 2 of M.-K. Lee, J. W. Kim, J. E. Song, and K. Park, "Sliding Window Method for NTRU", LNCS 4521.

Parameters:

w - the window size

Returns:

an array [b_0, ... b_{w-1}] of bit pattern locations

equals

public boolean equals(java.lang.Object other)

Compare this binary polynomial with the given object.

Overrides:

equals in class java.lang.Object

Parameters:

other - the other object

Returns:

the result of the comparison

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

Returns:

the hash code of this polynomial

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

Returns:

a human readable form of this polynomial

numCoeffs

int numCoeffs()

Compute the number of 1 coefficients of this binary polynomial.

Returns:

the number of 1 coefficients