org.spongycastle.pqc.crypto.rainbow.util

Class ComputeInField

java.lang.Object

org.spongycastle.pqc.crypto.rainbow.util.ComputeInField

public class ComputeInField
extends java.lang.Object

This class offers different operations on matrices in field GF2^8.

Implemented are functions: - finding inverse of a matrix - solving linear equation systems using the Gauss-Elimination method - basic operations like matrix multiplication, addition and so on.

Constructor Summary

Constructors

Constructor and Description
ComputeInField() Constructor with no parameters

Method Summary

Modifier and Type	Method and Description
short[][]	addSquareMatrix(short[][] matrix1, short[][] matrix2) Adds the n x n matrices matrix1 and matrix2
short[]	addVect(short[] vector1, short[] vector2) Addition of two vectors
short[][]	inverse(short[][] coef) This function computes the inverse of a given matrix using the Gauss- Elimination method.
short[]	multiplyMatrix(short[][] M1, short[] m) This function multiplies a given matrix with a one-dimensional array.
short[][]	multiplyMatrix(short[][] M1, short[][] M2) This function multiplies two given matrices.
short[][]	multMatrix(short scalar, short[][] matrix) Multiplies matrix with scalar
short[]	multVect(short scalar, short[] vector) Multiplies vector with scalar
short[][]	multVects(short[] vector1, short[] vector2) Multiplication of column vector with row vector
short[]	solveEquation(short[][] B, short[] b) This function finds a solution of the equation Bx = b.

Methods inherited from class java.lang.Object

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

Constructor Detail

ComputeInField

public ComputeInField()

Constructor with no parameters

Method Detail

solveEquation

public short[] solveEquation(short[][] B,
                             short[] b)

This function finds a solution of the equation Bx = b. Exception is thrown if the linear equation system has no solution

Parameters:

B - this matrix is the left part of the equation (B in the equation above)

b - the right part of the equation (b in the equation above)

Returns:

x the solution of the equation if it is solvable null otherwise

Throws:

java.lang.RuntimeException - if LES is not solvable

inverse

public short[][] inverse(short[][] coef)

This function computes the inverse of a given matrix using the Gauss- Elimination method.

An exception is thrown if the matrix has no inverse

Parameters:

coef - the matrix which inverse matrix is needed

Returns:

inverse matrix of the input matrix. If the matrix is singular, null is returned.

Throws:

java.lang.RuntimeException - if the given matrix is not invertible

multiplyMatrix

public short[][] multiplyMatrix(short[][] M1,
                                short[][] M2)
                         throws java.lang.RuntimeException

This function multiplies two given matrices. If the given matrices cannot be multiplied due to different sizes, an exception is thrown.

Parameters:

M1 - -the 1st matrix

M2 - -the 2nd matrix

Returns:

A = M1*M2

Throws:

java.lang.RuntimeException - in case the given matrices cannot be multiplied due to different dimensions.

multiplyMatrix

public short[] multiplyMatrix(short[][] M1,
                              short[] m)
                       throws java.lang.RuntimeException

This function multiplies a given matrix with a one-dimensional array.

An exception is thrown, if the number of columns in the matrix and the number of rows in the one-dim. array differ.

Parameters:

M1 - the matrix to be multiplied

m - the one-dimensional array to be multiplied

Returns:

M1*m

Throws:

java.lang.RuntimeException - in case of dimension inconsistency

addVect

public short[] addVect(short[] vector1,
                       short[] vector2)

Addition of two vectors

Parameters:

vector1 - first summand, always of dim n

vector2 - second summand, always of dim n

Returns:

addition of vector1 and vector2

Throws:

java.lang.RuntimeException - in case the addition is impossible due to inconsistency in the dimensions

multVects

public short[][] multVects(short[] vector1,
                           short[] vector2)

Multiplication of column vector with row vector

Parameters:

vector1 - column vector, always n x 1

vector2 - row vector, always 1 x n

Returns:

resulting n x n matrix of multiplication

Throws:

java.lang.RuntimeException - in case the multiplication is impossible due to inconsistency in the dimensions

multVect

public short[] multVect(short scalar,
                        short[] vector)

Multiplies vector with scalar

Parameters:

scalar - galois element to multiply vector with

vector - vector to be multiplied

Returns:

vector multiplied with scalar

multMatrix

public short[][] multMatrix(short scalar,
                            short[][] matrix)

Multiplies matrix with scalar

Parameters:

scalar - galois element to multiply matrix with

matrix - 2-dim n x n matrix to be multiplied

Returns:

matrix multiplied with scalar

addSquareMatrix

public short[][] addSquareMatrix(short[][] matrix1,
                                 short[][] matrix2)

Adds the n x n matrices matrix1 and matrix2

Parameters:

matrix1 - first summand

matrix2 - second summand

Returns:

addition of matrix1 and matrix2; both having the dimensions n x n

Throws:

java.lang.RuntimeException - in case the addition is not possible because of different dimensions of the matrices