Package org.bouncycastle.math.ec

Class ECFieldElement.F2m

java.lang.Object

org.bouncycastle.math.ec.ECFieldElement

org.bouncycastle.math.ec.ECFieldElement.F2m

All Implemented Interfaces:

ECConstants

Enclosing class:

ECFieldElement

public static class ECFieldElement.F2m
extends ECFieldElement

Class representing the Elements of the finite field F2m in polynomial basis (PB) representation. Both trinomial (TPB) and pentanomial (PPB) polynomial basis representations are supported. Gaussian normal basis (GNB) representation is not supported.

Nested Class Summary

Nested classes/interfaces inherited from class org.bouncycastle.math.ec.ECFieldElement

ECFieldElement.F2m, ECFieldElement.Fp

Field Summary

Fields

Modifier and Type	Field	Description
static int	GNB	Indicates gaussian normal basis representation (GNB).
static int	PPB	Indicates pentanomial basis representation (PPB).
static int	TPB	Indicates trinomial basis representation (TPB).

Fields inherited from interface org.bouncycastle.math.ec.ECConstants

FOUR, ONE, THREE, TWO, ZERO

Constructor Summary

Constructors

Constructor	Description
F2m(int m, int k1, int k2, int k3, BigInteger x)	Constructor for PPB.
F2m(int m, int k, BigInteger x)	Constructor for TPB.

Method Summary

Modifier and Type	Method	Description
ECFieldElement	add(ECFieldElement b)
static void	checkFieldElements(ECFieldElement a, ECFieldElement b)	Checks, if the ECFieldElements a and b are elements of the same field F2m (having the same representation).
ECFieldElement	divide(ECFieldElement b)
boolean	equals(Object anObject)	Compares this instance with the specified object and indicates if they are equal.
String	getFieldName()
int	getFieldSize()
int	getK1()
int	getK2()
int	getK3()
int	getM()
int	getRepresentation()
int	hashCode()	Returns an integer hash code for this object.
ECFieldElement	invert()
ECFieldElement	multiply(ECFieldElement b)
ECFieldElement	negate()
ECFieldElement	sqrt()
ECFieldElement	square()
ECFieldElement	subtract(ECFieldElement b)
BigInteger	toBigInteger()

Methods inherited from class org.bouncycastle.math.ec.ECFieldElement

toString

Methods inherited from class java.lang.Object

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

Field Details

GNB

public static final int GNB

Indicates gaussian normal basis representation (GNB). Number chosen according to X9.62. GNB is not implemented at present.

See Also:

Constant Field Values

TPB

public static final int TPB

Indicates trinomial basis representation (TPB). Number chosen according to X9.62.

See Also:

Constant Field Values

PPB

public static final int PPB

Indicates pentanomial basis representation (PPB). Number chosen according to X9.62.

See Also:

Constant Field Values

Constructor Details

F2m

public F2m(int m, int k1, int k2, int k3, BigInteger x)

Constructor for PPB.

Parameters:

m - The exponent m of F2m.

k1 - The integer k1 where xm + xk3 + xk2 + xk1 + 1 represents the reduction polynomial f(z).

k2 - The integer k2 where xm + xk3 + xk2 + xk1 + 1 represents the reduction polynomial f(z).

k3 - The integer k3 where xm + xk3 + xk2 + xk1 + 1 represents the reduction polynomial f(z).

x - The BigInteger representing the value of the field element.

F2m

public F2m(int m, int k, BigInteger x)

Constructor for TPB.

Parameters:

m - The exponent m of F2m.

k - The integer k where xm + xk + 1 represents the reduction polynomial f(z).

x - The BigInteger representing the value of the field element.

Method Details

toBigInteger

public BigInteger toBigInteger()

Specified by:

toBigInteger in class ECFieldElement

getFieldName

public String getFieldName()

Specified by:

getFieldName in class ECFieldElement

getFieldSize

public int getFieldSize()

Specified by:

getFieldSize in class ECFieldElement

checkFieldElements

public static void checkFieldElements(ECFieldElement a, ECFieldElement b)

Checks, if the ECFieldElements a and b are elements of the same field F2m (having the same representation).

Parameters:

a - field element.

b - field element to be compared.

Throws:

IllegalArgumentException - if a and b are not elements of the same field F2m (having the same representation).

add

public ECFieldElement add(ECFieldElement b)

Specified by:

add in class ECFieldElement

subtract

public ECFieldElement subtract(ECFieldElement b)

Specified by:

subtract in class ECFieldElement

multiply

public ECFieldElement multiply(ECFieldElement b)

Specified by:

multiply in class ECFieldElement

divide

public ECFieldElement divide(ECFieldElement b)

Specified by:

divide in class ECFieldElement

negate

public ECFieldElement negate()

Specified by:

negate in class ECFieldElement

square

public ECFieldElement square()

Specified by:

square in class ECFieldElement

invert

public ECFieldElement invert()

Specified by:

invert in class ECFieldElement

sqrt

public ECFieldElement sqrt()

Specified by:

sqrt in class ECFieldElement

getRepresentation

public int getRepresentation()

Returns:

the representation of the field F2m, either of TPB (trinomial basis representation) or PPB (pentanomial basis representation).

getM

public int getM()

Returns:

the degree m of the reduction polynomial f(z).

getK1

public int getK1()

Returns:

TPB: The integer k where xm + xk + 1 represents the reduction polynomial f(z).
PPB: The integer k1 where xm + xk3 + xk2 + xk1 + 1 represents the reduction polynomial f(z).

getK2

public int getK2()

Returns:

TPB: Always returns 0
PPB: The integer k2 where xm + xk3 + xk2 + xk1 + 1 represents the reduction polynomial f(z).

getK3

public int getK3()

Returns:

TPB: Always set to 0
PPB: The integer k3 where xm + xk3 + xk2 + xk1 + 1 represents the reduction polynomial f(z).

equals

public boolean equals(Object anObject)

Description copied from class: Object

Compares this instance with the specified object and indicates if they are equal. In order to be equal, o must represent the same object as this instance using a class-specific comparison. The general contract is that this comparison should be reflexive, symmetric, and transitive. Also, no object reference other than null is equal to null.

The default implementation returns true only if this == o. See Writing a correct equals method if you intend implementing your own equals method.

The general contract for the equals and Object.hashCode() methods is that if equals returns true for any two objects, then hashCode() must return the same value for these objects. This means that subclasses of Object usually override either both methods or neither of them.

Overrides:

equals in class Object

Parameters:

anObject - the object to compare this instance with.

Returns:

true if the specified object is equal to this Object; false otherwise.

See Also:

Object.hashCode()

hashCode

public int hashCode()

Description copied from class: Object

Returns an integer hash code for this object. By contract, any two objects for which Object.equals(java.lang.Object) returns true must return the same hash code value. This means that subclasses of Object usually override both methods or neither method.

Note that hash values must not change over time unless information used in equals comparisons also changes.

See Writing a correct hashCode method if you intend implementing your own hashCode method.

Overrides:

hashCode in class Object

Returns:

this object's hash code.

See Also:

Object.equals(java.lang.Object)