org.spongycastle.pqc.math.linearalgebra

Class GF2Matrix

java.lang.Object

org.spongycastle.pqc.math.linearalgebra.Matrix

org.spongycastle.pqc.math.linearalgebra.GF2Matrix

public class GF2Matrix
extends Matrix

This class describes some operations with matrices over finite field GF(2) and is used in ecc and MQ-PKC (also has some specific methods and implementation)

Field Summary

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

MATRIX_TYPE_RANDOM_LT, MATRIX_TYPE_RANDOM_REGULAR, MATRIX_TYPE_RANDOM_UT, MATRIX_TYPE_UNIT, MATRIX_TYPE_ZERO, numColumns, numRows

Constructor Summary

Constructors

Constructor and Description
GF2Matrix(byte[] enc) Create the matrix from encoded form.
GF2Matrix(GF2Matrix a) Copy constructor.
GF2Matrix(int n, char typeOfMatrix) Create an nxn matrix of the given type.
GF2Matrix(int n, char typeOfMatrix, java.security.SecureRandom sr) Create an nxn matrix of the given type.
GF2Matrix(int numColumns, int[][] matrix) Create the matrix with the contents of the given array.

Method Summary

Modifier and Type	Method and Description
Matrix	computeInverse() Compute the inverse of this matrix.
Matrix	computeTranspose() Compute the transpose of this matrix.
static GF2Matrix[]	createRandomRegularMatrixAndItsInverse(int n, java.security.SecureRandom sr) Create a nxn random regular matrix and its inverse.
boolean	equals(java.lang.Object other) Compare this matrix with another object.
GF2Matrix	extendLeftCompactForm() Compute the full form matrix (this | Id) from this matrix in left compact form, where Id is the k x k identity matrix and k is the number of rows of this matrix.
GF2Matrix	extendRightCompactForm() Compute the full form matrix (Id | this) from this matrix in right compact form, where Id is the k x k identity matrix and k is the number of rows of this matrix.
byte[]	getEncoded() Returns encoded matrix, i.e., this matrix in byte array form
double	getHammingWeight() Returns the percentage of the number of "ones" in this matrix.
int[][]	getIntArray()
GF2Matrix	getLeftSubMatrix() Get the quadratic submatrix of this matrix consisting of the leftmost numRows columns.
int	getLength()
GF2Matrix	getRightSubMatrix() Get the submatrix of this matrix consisting of the rightmost numColumns-numRows columns.
int[]	getRow(int index) Return the row of this matrix with the given index.
int	hashCode()
boolean	isZero() Check if this is the zero matrix (i.e., all entries are zero).
Matrix	leftMultiply(Permutation p) Compute the product of a permutation matrix (which is generated from an n-permutation) and this matrix.
Vector	leftMultiply(Vector vec) compute product a row vector and this matrix
Vector	leftMultiplyLeftCompactForm(Vector vec) Compute the product of the matrix (this | Id) and a column vector, where Id is a (numRows x numRows) unit matrix.
Matrix	rightMultiply(Matrix mat) Compute the product of this matrix and a matrix A over GF(2).
Matrix	rightMultiply(Permutation p) Compute the product of this matrix and a permutation matrix which is generated from an n-permutation.
Vector	rightMultiply(Vector vec) Compute the product of this matrix and the given column vector.
Vector	rightMultiplyRightCompactForm(Vector vec) Compute the product of the matrix (Id | this) and a column vector, where Id is a (numRows x numRows) unit matrix.
java.lang.String	toString()

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

getNumColumns, getNumRows

Methods inherited from class java.lang.Object

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

Constructor Detail

GF2Matrix

public GF2Matrix(byte[] enc)

Create the matrix from encoded form.

Parameters:

enc - the encoded matrix

GF2Matrix

public GF2Matrix(int numColumns,
                 int[][] matrix)

Create the matrix with the contents of the given array. The matrix is not copied. Unused coefficients are masked out.

Parameters:

numColumns - the number of columns

matrix - the element array

GF2Matrix

public GF2Matrix(int n,
                 char typeOfMatrix)

Create an nxn matrix of the given type.

Parameters:

n - the number of rows (and columns)

typeOfMatrix - the martix type (see Matrix for predefined constants)

GF2Matrix

public GF2Matrix(int n,
                 char typeOfMatrix,
                 java.security.SecureRandom sr)

Create an nxn matrix of the given type.

Parameters:

n - the matrix size

typeOfMatrix - the matrix type

sr - the source of randomness

GF2Matrix

public GF2Matrix(GF2Matrix a)

Copy constructor.

Parameters:

a - another GF2Matrix

Method Detail

createRandomRegularMatrixAndItsInverse

public static GF2Matrix[] createRandomRegularMatrixAndItsInverse(int n,
                                                                 java.security.SecureRandom sr)

Create a nxn random regular matrix and its inverse.

Parameters:

n - number of rows (and columns)

sr - source of randomness

Returns:

the created random regular matrix and its inverse

getIntArray

public int[][] getIntArray()

Returns:

the array keeping the matrix elements

getLength

public int getLength()

Returns:

the length of each array representing a row of this matrix

getRow

public int[] getRow(int index)

Return the row of this matrix with the given index.

Parameters:

index - the index

Returns:

the row of this matrix with the given index

getEncoded

public byte[] getEncoded()

Returns encoded matrix, i.e., this matrix in byte array form

Specified by:

getEncoded in class Matrix

Returns:

the encoded matrix

getHammingWeight

public double getHammingWeight()

Returns the percentage of the number of "ones" in this matrix.

Returns:

the Hamming weight of this matrix (as a ratio).

isZero

public boolean isZero()

Check if this is the zero matrix (i.e., all entries are zero).

Specified by:

isZero in class Matrix

Returns:

true if this is the zero matrix

getLeftSubMatrix

public GF2Matrix getLeftSubMatrix()

Get the quadratic submatrix of this matrix consisting of the leftmost numRows columns.

Returns:

the (numRows x numRows) submatrix

extendLeftCompactForm

public GF2Matrix extendLeftCompactForm()

Compute the full form matrix (this | Id) from this matrix in left compact form, where Id is the k x k identity matrix and k is the number of rows of this matrix.

Returns:

(this | Id)

getRightSubMatrix

public GF2Matrix getRightSubMatrix()

Get the submatrix of this matrix consisting of the rightmost numColumns-numRows columns.

Returns:

the (numRows x (numColumns-numRows)) submatrix

extendRightCompactForm

public GF2Matrix extendRightCompactForm()

Compute the full form matrix (Id | this) from this matrix in right compact form, where Id is the k x k identity matrix and k is the number of rows of this matrix.

Returns:

(Id | this)

computeTranspose

public Matrix computeTranspose()

Compute the transpose of this matrix.

Returns:

(this)^T

computeInverse

public Matrix computeInverse()

Compute the inverse of this matrix.

Specified by:

computeInverse in class Matrix

Returns:

the inverse of this matrix (newly created).

Throws:

java.lang.ArithmeticException - if this matrix is not invertible.

leftMultiply

public Matrix leftMultiply(Permutation p)

Compute the product of a permutation matrix (which is generated from an n-permutation) and this matrix.

Parameters:

p - the permutation

Returns:

GF2Matrix P*this

leftMultiply

public Vector leftMultiply(Vector vec)

compute product a row vector and this matrix

Specified by:

leftMultiply in class Matrix

Parameters:

vec - a vector over GF(2)

Returns:

Vector product a*matrix

leftMultiplyLeftCompactForm

public Vector leftMultiplyLeftCompactForm(Vector vec)

Compute the product of the matrix (this | Id) and a column vector, where Id is a (numRows x numRows) unit matrix.

Parameters:

vec - the vector over GF(2)

Returns:

(this | Id)*vector

rightMultiply

public Matrix rightMultiply(Matrix mat)

Compute the product of this matrix and a matrix A over GF(2).

Specified by:

rightMultiply in class Matrix

Parameters:

mat - a matrix A over GF(2)

Returns:

matrix product this*matrixA

rightMultiply

public Matrix rightMultiply(Permutation p)

Compute the product of this matrix and a permutation matrix which is generated from an n-permutation.

Specified by:

rightMultiply in class Matrix

Parameters:

p - the permutation

Returns:

GF2Matrix this*P

rightMultiply

public Vector rightMultiply(Vector vec)

Compute the product of this matrix and the given column vector.

Specified by:

rightMultiply in class Matrix

Parameters:

vec - the vector over GF(2)

Returns:

this*vector

rightMultiplyRightCompactForm

public Vector rightMultiplyRightCompactForm(Vector vec)

Compute the product of the matrix (Id | this) and a column vector, where Id is a (numRows x numRows) unit matrix.

Parameters:

vec - the vector over GF(2)

Returns:

(Id | this)*vector

equals

public boolean equals(java.lang.Object other)

Compare this matrix with another object.

Overrides:

equals in class java.lang.Object

Parameters:

other - another object

Returns:

the result of the comparison

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

Returns:

the hash code of this matrix

toString

public java.lang.String toString()

Specified by:

toString in class Matrix

Returns:

a human readable form of the matrix