de.flexiprovider.common.math.polynomials
Class SparseBinaryConvolutionPolynomial

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

All Implemented Interfaces:

ConvolutionPolynomial

public class SparseBinaryConvolutionPolynomial

extends java.lang.Object

implements ConvolutionPolynomial

This class represents sparse binary polynomials in the ring Z(X)/(X^N-1). The polynomials are stored as int arrays of the degrees of the monomials with coefficient 1.

Author:

Martin Döring

Field Summary

(package private) int[]	degrees The array of the degrees of the monomials with coefficient 1
(package private) int	N The degree of the reduction polynomial

Constructor Summary

SparseBinaryConvolutionPolynomial(BinaryConvolutionPolynomial binPol)
Construct a SparseBinaryConvolutionPolynomial out of the given BinaryConvolutionPolynomial.

SparseBinaryConvolutionPolynomial(int N, int[] degrees)
Create a sparse binary polynomial out of the given degree array

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

SparseBinaryConvolutionPolynomial(SparseBinaryConvolutionPolynomial other)
Copy constructor.

Method Summary

boolean	equals(java.lang.Object other) Compare this 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[][]	getPatterns() Compute an array of bit pattern locations (minimal size).
int	hashCode()
static SparseBinaryConvolutionPolynomial	OS2REP(int N, int d, byte[] encoded) Create a sparse binary polynomial out of the given byte array.
byte[]	RE2OSP() Encode this polynomial as a byte array.
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

degrees

int[] degrees

The array of the degrees of the monomials with coefficient 1

Constructor Detail

SparseBinaryConvolutionPolynomial

public SparseBinaryConvolutionPolynomial(int N,
                                         int[] degrees)

Create a sparse binary polynomial out of the given degree array

Parameters:

N - the degree of the reduction polynomial

degrees - the array of the degrees of the monomials with coefficient 1

SparseBinaryConvolutionPolynomial

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

Create a sparse 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

SparseBinaryConvolutionPolynomial

public SparseBinaryConvolutionPolynomial(BinaryConvolutionPolynomial binPol)

Construct a SparseBinaryConvolutionPolynomial out of the given BinaryConvolutionPolynomial.

Parameters:

binPol - the BinaryPolynomial

SparseBinaryConvolutionPolynomial

public SparseBinaryConvolutionPolynomial(SparseBinaryConvolutionPolynomial other)

Copy constructor.

Parameters:

other - another SparseBinaryPolynomial

Method Detail

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

getPatterns

public int[][] getPatterns()

Compute an array of bit pattern locations (minimal size).

Returns:

an array of bit pattern locations

equals

public boolean equals(java.lang.Object other)

Compare this 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

RE2OSP

public byte[] RE2OSP()

Encode this polynomial as a byte array.

Returns:

the encoded polynomial

OS2REP

public static SparseBinaryConvolutionPolynomial OS2REP(int N,
                                                       int d,
                                                       byte[] encoded)
                                                throws java.lang.IllegalArgumentException

Create a sparse binary polynomial out of the given byte array.

Parameters:

N - the degree of the reduction polynomial

d - the number of non-zero coefficients

encoded - an encoded sparse binary polynomial

Returns:

the decoded polynomial

Throws:

java.lang.IllegalArgumentException - if the encoded polynomial has wrong length.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

Returns:

a human readable form of this polynomial