org.spongycastle.pqc.math.linearalgebra

Class GF2Vector

java.lang.Object

org.spongycastle.pqc.math.linearalgebra.Vector

org.spongycastle.pqc.math.linearalgebra.GF2Vector

public class GF2Vector
extends Vector

This class implements the abstract class Vector for the case of vectors over the finite field GF(2).
For the vector representation the array of type int[] is used, thus one element of the array holds 32 elements of the vector.

See Also:

Vector

Field Summary

Fields inherited from class org.spongycastle.pqc.math.linearalgebra.Vector

length

Constructor Summary

Constructors

Modifier	Constructor and Description
	GF2Vector(GF2Vector other) Copy constructor.
	GF2Vector(int length) Construct the zero vector of the given length.
protected	GF2Vector(int[] v, int length) Construct a new GF2Vector of the given length and with the given element array.
	GF2Vector(int length, int[] v) Construct a GF2Vector of the given length and with elements from the given array.
	GF2Vector(int length, int t, java.security.SecureRandom sr) Construct a random GF2Vector of the given length with the specified number of non-zero coefficients.
	GF2Vector(int length, java.security.SecureRandom sr) Construct a random GF2Vector of the given length.

Method Summary

Modifier and Type	Method and Description
Vector	add(Vector other) Adds another GF2Vector to this vector.
boolean	equals(java.lang.Object other) Check if the given object is equal to this vector.
GF2Vector	extractLeftVector(int k) Return a new vector consisting of the first k elements of this vector.
GF2Vector	extractRightVector(int k) Return a new vector consisting of the last k elements of this vector.
GF2Vector	extractVector(int[] setJ) Return a new vector consisting of the elements of this vector with the indices given by the set setJ.
int	getBit(int index) Return the value of the bit of this vector at the specified index.
byte[]	getEncoded() Encode this vector as byte array.
int	getHammingWeight() Return the Hamming weight of this vector, i.e., compute the number of units of this vector.
int[]	getVecArray()
int	hashCode()
boolean	isZero() Return whether this is the zero vector (i.e., all elements are zero).
Vector	multiply(Permutation p) Multiply this vector with a permutation.
static GF2Vector	OS2VP(int length, byte[] encVec) Construct a new GF2Vector with the given length out of the encoded vector.
void	setBit(int index) Set the coefficient at the given index to 1.
GF2mVector	toExtensionFieldVector(GF2mField field) Rewrite this vector as a vector over GF(2m) with t elements.
java.lang.String	toString()

Methods inherited from class org.spongycastle.pqc.math.linearalgebra.Vector

getLength

Methods inherited from class java.lang.Object

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

Constructor Detail

GF2Vector

public GF2Vector(int length)

Construct the zero vector of the given length.

Parameters:

length - the length of the vector

GF2Vector

public GF2Vector(int length,
                 java.security.SecureRandom sr)

Construct a random GF2Vector of the given length.

Parameters:

length - the length of the vector

sr - the source of randomness

GF2Vector

public GF2Vector(int length,
                 int t,
                 java.security.SecureRandom sr)

Construct a random GF2Vector of the given length with the specified number of non-zero coefficients.

Parameters:

length - the length of the vector

t - the number of non-zero coefficients

sr - the source of randomness

GF2Vector

public GF2Vector(int length,
                 int[] v)

Construct a GF2Vector of the given length and with elements from the given array. The array is copied and unused bits are masked out.

Parameters:

length - the length of the vector

v - the element array

GF2Vector

public GF2Vector(GF2Vector other)

Copy constructor.

Parameters:

other - another GF2Vector

GF2Vector

protected GF2Vector(int[] v,
                    int length)

Construct a new GF2Vector of the given length and with the given element array. The array is not changed and only a reference to the array is stored. No length checking is performed either.

Parameters:

v - the element array

length - the length of the vector

Method Detail

OS2VP

public static GF2Vector OS2VP(int length,
                              byte[] encVec)

Construct a new GF2Vector with the given length out of the encoded vector.

Parameters:

length - the length of the vector

encVec - the encoded vector

Returns:

the decoded vector

getEncoded

public byte[] getEncoded()

Encode this vector as byte array.

Specified by:

getEncoded in class Vector

Returns:

the encoded vector

getVecArray

public int[] getVecArray()

Returns:

the int array representation of this vector

getHammingWeight

public int getHammingWeight()

Return the Hamming weight of this vector, i.e., compute the number of units of this vector.

Returns:

the Hamming weight of this vector

isZero

public boolean isZero()

Description copied from class: Vector

Return whether this is the zero vector (i.e., all elements are zero).

Specified by:

isZero in class Vector

Returns:

whether this is the zero vector (i.e., all elements are zero)

getBit

public int getBit(int index)

Return the value of the bit of this vector at the specified index.

Parameters:

index - the index

Returns:

the value of the bit (0 or 1)

setBit

public void setBit(int index)

Set the coefficient at the given index to 1. If the index is out of bounds, do nothing.

Parameters:

index - the index of the coefficient to set

add

public Vector add(Vector other)

Adds another GF2Vector to this vector.

Specified by:

add in class Vector

Parameters:

other - another GF2Vector

Returns:

this + other

Throws:

java.lang.ArithmeticException - if the other vector is not a GF2Vector or has another length.

multiply

public Vector multiply(Permutation p)

Multiply this vector with a permutation.

Specified by:

multiply in class Vector

Parameters:

p - the permutation

Returns:

this*p = p*this

extractVector

public GF2Vector extractVector(int[] setJ)

Return a new vector consisting of the elements of this vector with the indices given by the set setJ.

Parameters:

setJ - the set of indices of elements to extract

Returns:

the new GF2Vector [this_setJ[0], this_setJ[1], ..., this_setJ[#setJ-1]]

extractLeftVector

public GF2Vector extractLeftVector(int k)

Return a new vector consisting of the first k elements of this vector.

Parameters:

k - the number of elements to extract

Returns:

a new GF2Vector consisting of the first k elements of this vector

extractRightVector

public GF2Vector extractRightVector(int k)

Return a new vector consisting of the last k elements of this vector.

Parameters:

k - the number of elements to extract

Returns:

a new GF2Vector consisting of the last k elements of this vector

toExtensionFieldVector

public GF2mVector toExtensionFieldVector(GF2mField field)

Rewrite this vector as a vector over GF(2^m) with t elements.

Parameters:

field - the finite field GF(2^m)

Returns:

the converted vector over GF(2^m)

equals

public boolean equals(java.lang.Object other)

Check if the given object is equal to this vector.

Specified by:

equals in class Vector

Parameters:

other - vector

Returns:

the result of the comparison

hashCode

public int hashCode()

Specified by:

hashCode in class Vector

Returns:

the hash code of this vector

toString

public java.lang.String toString()

Specified by:

toString in class Vector

Returns:

a human readable form of this vector