org.cryptimeleon.math.structures.rings.extfield

Class ExtensionFieldElement

java.lang.Object

org.cryptimeleon.math.structures.rings.extfield.ExtensionFieldElement

All Implemented Interfaces:

UniqueByteRepresentable, Representable, Element, FieldElement, RingElement

public class ExtensionFieldElement
extends java.lang.Object
implements FieldElement, UniqueByteRepresentable

Elements in ExtensionField.

Constructor Summary

Constructors

Constructor and Description
ExtensionFieldElement(ExtensionField f, FieldElement[] coefficients)

Method Summary

Modifier and Type	Method and Description
ExtensionFieldElement	add(Element e) Computes \(\text{this} + e\).
ExtensionFieldElement	applyFrobenius() Computes this^characteristic.
java.math.BigInteger	asInteger() Interprets this element as an integer.
ExtensionFieldElement	conjugate() Computes the conjugate of this element.
boolean	equals(java.lang.Object obj)
FieldElement[]	getCoefficients() The coefficients of the polynomial over getStructure().getBaseField() defining this element
Representation	getRepresentation() The representation of this object.
ExtensionField	getStructure() Returns the Structure that this Element belongs to.
int	hashCode()
ExtensionFieldElement	inv() Computes the multiplicative inverse of this element.
ExtensionFieldElement	mul(Element e) Computes \(\text{this} \cdot e\).
ExtensionFieldElement	neg() Computes the additive inverse of this element.
ExtensionFieldElement	reduce()
java.lang.String	toString()
ByteAccumulator	updateAccumulator(ByteAccumulator accumulator) Updates the ByteAccumulator with the unique byte representation of this object.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.cryptimeleon.math.structures.rings.FieldElement

applyFrobenius, div, divides, divideWithRemainder, getRank, mul, mul, pow, pow, square, sub

Methods inherited from interface org.cryptimeleon.math.structures.rings.RingElement

isOne, isUnit, isZero, toAdditiveGroupElement, toUnitGroupElement

Methods inherited from interface org.cryptimeleon.math.hash.UniqueByteRepresentable

getUniqueByteRepresentation

Constructor Detail

ExtensionFieldElement

public ExtensionFieldElement(ExtensionField f,
                             FieldElement[] coefficients)

Method Detail

getRepresentation

public Representation getRepresentation()

Description copied from interface: Representable

The representation of this object. Used for serialization. A convenient way to implement this is using @link ReprUtil

Specified by:

getRepresentation in interface Representable

Returns:

a Representation or null if an equal object can be recreated without any information.

See Also:

Representation

add

public ExtensionFieldElement add(Element e)

Description copied from interface: RingElement

Computes \(\text{this} + e\).

Specified by:

add in interface FieldElement

Specified by:

add in interface RingElement

Parameters:

e - the addend

Returns:

the result

neg

public ExtensionFieldElement neg()

Description copied from interface: RingElement

Computes the additive inverse of this element.

Specified by:

neg in interface FieldElement

Specified by:

neg in interface RingElement

Returns:

the result

mul

public ExtensionFieldElement mul(Element e)

Description copied from interface: RingElement

Computes \(\text{this} \cdot e\).

Specified by:

mul in interface FieldElement

Specified by:

mul in interface RingElement

Parameters:

e - the factor

Returns:

the result

getCoefficients

public FieldElement[] getCoefficients()

The coefficients of the polynomial over getStructure().getBaseField() defining this element

inv

public ExtensionFieldElement inv()
                          throws java.lang.UnsupportedOperationException

Description copied from interface: RingElement

Computes the multiplicative inverse of this element.

Specified by:

inv in interface FieldElement

Specified by:

inv in interface RingElement

Returns:

the result

Throws:

java.lang.UnsupportedOperationException - if this is not a unit

conjugate

public ExtensionFieldElement conjugate()

Computes the conjugate of this element.

For an element x with coefficients in F_q, compute x^q.

Returns:

the first conjugate of this element

applyFrobenius

public ExtensionFieldElement applyFrobenius()

Description copied from interface: FieldElement

Computes this^characteristic.

Specified by:

applyFrobenius in interface FieldElement

getStructure

public ExtensionField getStructure()

Description copied from interface: Element

Returns the Structure that this Element belongs to.

Specified by:

getStructure in interface Element

Specified by:

getStructure in interface FieldElement

Specified by:

getStructure in interface RingElement

hashCode

public int hashCode()

Specified by:

hashCode in interface Element

Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(java.lang.Object obj)

Specified by:

equals in interface Element

Overrides:

equals in class java.lang.Object

reduce

public ExtensionFieldElement reduce()

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

updateAccumulator

public ByteAccumulator updateAccumulator(ByteAccumulator accumulator)

Description copied from interface: UniqueByteRepresentable

Updates the ByteAccumulator with the unique byte representation of this object.

The input to the accumulators update function is an injective (with respect to a given domain) byte encoding of this object.

For many use-cases, the AnnotatedUbrUtil can be used to quickly implement this method.

Specified by:

updateAccumulator in interface UniqueByteRepresentable

Returns:

the same accumulator as was input

asInteger

public java.math.BigInteger asInteger()
                               throws java.lang.UnsupportedOperationException

Description copied from interface: RingElement

Interprets this element as an integer.

Result will be between 0 and the ring's characteristic.

Formally, this method shall return the inverse of Ring.getElement(BigInteger), i.e. x.getStructure().getElement(x.asInteger()).equals(x) (if asInteger() doesn't throw an exception).

Specified by:

asInteger in interface RingElement

Returns:

the integer corresponding to this element

Throws:

java.lang.UnsupportedOperationException - if no such element exists or cannot be efficiently computed