org.bouncycastle.pqc.math.linearalgebra

Class GF2nPolynomial

java.lang.Object

org.bouncycastle.pqc.math.linearalgebra.GF2nPolynomial

public class GF2nPolynomial
extends Object

This class implements polynomials over GF2nElements.

See Also:

GF2nElement

Constructor Summary

Constructors

Constructor and Description
GF2nPolynomial(GF2nPolynomial a) Creates a new PolynomialGF2n by cloning the given PolynomialGF2n a.
GF2nPolynomial(GF2Polynomial polynomial, GF2nField B1) Creates a new PolynomialGF2n from the given Bitstring polynomial over the GF2nField B1.
GF2nPolynomial(int deg, GF2nElement elem) Creates a new PolynomialGF2n of size deg and elem as coefficients.

Method Summary

Methods

Modifier and Type	Method and Description
GF2nPolynomial	add(GF2nPolynomial b) Adds the PolynomialGF2n b to this and returns the result in a new PolynomialGF2n.
void	assignZeroToElements()
GF2nElement	at(int index) Returns the coefficient at index.
GF2nPolynomial[]	divide(GF2nPolynomial b) Divides this by b and stores the result in a new PolynomialGF2n[2], quotient in result[0] and remainder in result[1].
void	enlarge(int k) Enlarges the size of this PolynomialGF2n to k + 1.
boolean	equals(Object other)
GF2nPolynomial	gcd(GF2nPolynomial g) Computes the greatest common divisor of this and g and returns the result in a new PolynomialGF2n.
int	getDegree() Returns the degree of this PolynomialGF2n.
int	hashCode()
boolean	isZero() Returns true if all coefficients equal zero.
GF2nPolynomial	multiply(GF2nPolynomial b) Multiplies this by b and returns the result in a new PolynomialGF2n.
GF2nPolynomial	multiplyAndReduce(GF2nPolynomial b, GF2nPolynomial g) Multiplies this by b, reduces the result by g and returns it in a new PolynomialGF2n.
GF2nPolynomial	quotient(GF2nPolynomial b) Divides this by b and stores the quotient in a new PolynomialGF2n.
GF2nPolynomial	reduce(GF2nPolynomial g) Reduces this by g and returns the result in a new PolynomialGF2n.
GF2nPolynomial	remainder(GF2nPolynomial b) Divides this by b and stores the remainder in a new PolynomialGF2n.
GF2nPolynomial	scalarMultiply(GF2nElement s) Multiplies the scalar s to each coefficient of this PolynomialGF2n and returns the result in a new PolynomialGF2n.
void	set(int index, GF2nElement elem) Sets the coefficient at index to elem.
GF2nPolynomial	shiftLeft(int amount)
void	shiftThisLeft(int amount) Shifts left this by amount and stores the result in this PolynomialGF2n.
void	shrink()
int	size() Returns the size (=maximum degree + 1) of this PolynomialGF2n.

Methods inherited from class java.lang.Object

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

Constructor Detail

GF2nPolynomial

public GF2nPolynomial(int deg,
              GF2nElement elem)

Creates a new PolynomialGF2n of size deg and elem as coefficients.

Parameters:

deg - - the maximum degree + 1

elem - - a GF2nElement

GF2nPolynomial

public GF2nPolynomial(GF2nPolynomial a)

Creates a new PolynomialGF2n by cloning the given PolynomialGF2n a.

Parameters:

a - the PolynomialGF2n to clone

GF2nPolynomial

public GF2nPolynomial(GF2Polynomial polynomial,
              GF2nField B1)

Creates a new PolynomialGF2n from the given Bitstring polynomial over the GF2nField B1.

Parameters:

polynomial - the Bitstring to use

B1 - the field

Method Detail

assignZeroToElements

public final void assignZeroToElements()

size

public final int size()

Returns the size (=maximum degree + 1) of this PolynomialGF2n. This is not the degree, use getDegree instead.

Returns:

the size (=maximum degree + 1) of this PolynomialGF2n.

getDegree

public final int getDegree()

Returns the degree of this PolynomialGF2n.

Returns:

the degree of this PolynomialGF2n.

enlarge

public final void enlarge(int k)

Enlarges the size of this PolynomialGF2n to k + 1.

Parameters:

k - the new maximum degree

shrink

public final void shrink()

set

public final void set(int index,
       GF2nElement elem)

Sets the coefficient at index to elem.

Parameters:

index - the index

elem - the GF2nElement to store as coefficient index

at

public final GF2nElement at(int index)

Returns the coefficient at index.

Parameters:

index - the index

Returns:

the GF2nElement stored as coefficient index

isZero

public final boolean isZero()

Returns true if all coefficients equal zero.

Returns:

true if all coefficients equal zero.

equals

public final boolean equals(Object other)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

Returns:

the hash code of this polynomial

add

public final GF2nPolynomial add(GF2nPolynomial b)
                         throws RuntimeException

Adds the PolynomialGF2n b to this and returns the result in a new PolynomialGF2n.

Parameters:

b - - the PolynomialGF2n to add

Returns:

this + b

Throws:

DifferentFieldsException - if this and b are not defined over the same field.

RuntimeException

scalarMultiply

public final GF2nPolynomial scalarMultiply(GF2nElement s)
                                    throws RuntimeException

Multiplies the scalar s to each coefficient of this PolynomialGF2n and returns the result in a new PolynomialGF2n.

Parameters:

s - the scalar to multiply

Returns:

this x s

Throws:

DifferentFieldsException - if this and s are not defined over the same field.

RuntimeException

multiply

public final GF2nPolynomial multiply(GF2nPolynomial b)
                              throws RuntimeException

Multiplies this by b and returns the result in a new PolynomialGF2n.

Parameters:

b - the PolynomialGF2n to multiply

Returns:

this * b

Throws:

DifferentFieldsException - if this and b are not defined over the same field.

RuntimeException

multiplyAndReduce

public final GF2nPolynomial multiplyAndReduce(GF2nPolynomial b,
                               GF2nPolynomial g)
                                       throws RuntimeException,
                                              ArithmeticException

Multiplies this by b, reduces the result by g and returns it in a new PolynomialGF2n.

Parameters:

b - the PolynomialGF2n to multiply

g - the modul

Returns:

this * b mod g

Throws:

DifferentFieldsException - if this, b and g are not all defined over the same field.

RuntimeException

ArithmeticException

reduce

public final GF2nPolynomial reduce(GF2nPolynomial g)
                            throws RuntimeException,
                                   ArithmeticException

Reduces this by g and returns the result in a new PolynomialGF2n.

Parameters:

g - - the modulus

Returns:

this % g

Throws:

DifferentFieldsException - if this and g are not defined over the same field.

RuntimeException

ArithmeticException

shiftThisLeft

public final void shiftThisLeft(int amount)

Shifts left this by amount and stores the result in this PolynomialGF2n.

Parameters:

amount - the amount to shift the coefficients

shiftLeft

public final GF2nPolynomial shiftLeft(int amount)

divide

public final GF2nPolynomial[] divide(GF2nPolynomial b)
                              throws RuntimeException,
                                     ArithmeticException

Divides this by b and stores the result in a new PolynomialGF2n[2], quotient in result[0] and remainder in result[1].

Parameters:

b - the divisor

Returns:

the quotient and remainder of this / b

Throws:

DifferentFieldsException - if this and b are not defined over the same field.

RuntimeException

ArithmeticException

remainder

public final GF2nPolynomial remainder(GF2nPolynomial b)
                               throws RuntimeException,
                                      ArithmeticException

Divides this by b and stores the remainder in a new PolynomialGF2n.

Parameters:

b - the divisor

Returns:

the remainder this % b

Throws:

DifferentFieldsException - if this and b are not defined over the same field.

RuntimeException

ArithmeticException

quotient

public final GF2nPolynomial quotient(GF2nPolynomial b)
                              throws RuntimeException,
                                     ArithmeticException

Divides this by b and stores the quotient in a new PolynomialGF2n.

Parameters:

b - the divisor

Returns:

the quotient this / b

Throws:

DifferentFieldsException - if this and b are not defined over the same field.

RuntimeException

ArithmeticException

gcd

public final GF2nPolynomial gcd(GF2nPolynomial g)
                         throws RuntimeException,
                                ArithmeticException

Computes the greatest common divisor of this and g and returns the result in a new PolynomialGF2n.

Parameters:

g - - a GF2nPolynomial

Returns:

gcd(this, g)

Throws:

DifferentFieldsException - if the coefficients of this and g use different fields

ArithmeticException - if coefficients are zero.

RuntimeException