org.cryptimeleon.math.structures.rings.cartesian

Class ProductRing

java.lang.Object

org.cryptimeleon.math.structures.rings.cartesian.ProductRing

All Implemented Interfaces:

RepresentationRestorer, Representable, StandaloneRepresentable, Ring, Structure

public class ProductRing
extends java.lang.Object
implements Ring

Field Summary

Fields

Modifier and Type	Field and Description
protected Ring[]	rings

Constructor Summary

Constructors

Constructor and Description
ProductRing(Representation repr)
ProductRing(Ring... rings)

Method Summary

Modifier and Type	Method and Description
boolean	equals(java.lang.Object other)
double	estimateCostInvPerOp() Estimates the number of inversions that can be done per group operation for the same cost.
double	estimateCostNegPerOp() Estimates the number of negations (additive inversions) that can be done per group operation for the same cost.
java.math.BigInteger	getCharacteristic() Returns the characteristic of the ring.
RingElement	getElement(java.math.BigInteger i) Maps the integer i into this ring \(R\), such that this map is a ring homomorphism \(\mathbb{Z}_{\text{getCharacteristic()}} \rightarrow R\).
RingElement	getOneElement() Returns the multiplicative neutral element of this ring.
Representation	getRepresentation() The representation of this object.
RingElement	getUniformlyRandomElement() Returns an element of this structure that is drawn uniformly at random using a cryptographically strong RNG.
java.util.Optional<java.lang.Integer>	getUniqueByteLength() Returns the number of bytes returned by this structure's UniqueByteRepresentable.getUniqueByteRepresentation(), or an empty Optional if this structure's elements do not guarantee a fixed length.
RingElement	getZeroElement() Returns the additive neutral element of this ring.
int	hashCode()
boolean	isCommutative() Returns true if this ring is known to be commutative.
RingElement	restoreElement(Representation repr) Creates an element of this structure from its representation.
java.math.BigInteger	size() Returns the number of elements in this structure (the size).
java.math.BigInteger	sizeUnitGroup() Returns the number of units in this ring.
static ProductRingElement	valueOf(RingElement... elems)

Methods inherited from class java.lang.Object

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

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

asAdditiveGroup, asUnitGroup, extendedEuclideanAlgorithm, extendedEuclideanAlgorithm, getElement, getUniformlyRandomElements, getUniformlyRandomNonzeroElement, getUniformlyRandomNonzeroElements, getUniformlyRandomUnit, getUniformlyRandomUnits, restoreFromRepresentation, restoreVector

Methods inherited from interface org.cryptimeleon.math.structures.Structure

hasPrimeSize

Field Detail

rings

protected Ring[] rings

Constructor Detail

ProductRing

public ProductRing(Ring... rings)

ProductRing

public ProductRing(Representation repr)

Method Detail

size

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

Description copied from interface: Structure

Returns the number of elements in this structure (the size).

Specified by:

size in interface Structure

Returns:

the number of elements contained in this structure or null if infinite

Throws:

java.lang.UnsupportedOperationException - if the number of elements is unknown or too expensive to compute

getUniformlyRandomElement

public RingElement getUniformlyRandomElement()
                                      throws java.lang.UnsupportedOperationException

Description copied from interface: Structure

Returns an element of this structure that is drawn uniformly at random using a cryptographically strong RNG.

Specified by:

getUniformlyRandomElement in interface Ring

Specified by:

getUniformlyRandomElement in interface Structure

Throws:

java.lang.UnsupportedOperationException - if the operation is not supported

getCharacteristic

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

Description copied from interface: Ring

Returns the characteristic of the ring.

The characteristic of a ring is defined to be the number n such that there is a ring homomorphism from Zn to the ring.

Specified by:

getCharacteristic in interface Ring

Throws:

java.lang.UnsupportedOperationException - if unknown

getElement

public RingElement getElement(java.math.BigInteger i)

Description copied from interface: Ring

Maps the integer i into this ring \(R\), such that this map is a ring homomorphism \(\mathbb{Z}_{\text{getCharacteristic()}} \rightarrow R\).

Specified by:

getElement in interface Ring

Parameters:

i - the integer to map

Returns:

an element of the ring

estimateCostInvPerOp

public double estimateCostInvPerOp()

Description copied from interface: Ring

Estimates the number of inversions that can be done per group operation for the same cost. For example, 2 would mean that an inversion costs half as much as a group operation, on average.

Specified by:

estimateCostInvPerOp in interface Ring

Returns:

estimated number of inversions that can be done per group operation for the same cost

estimateCostNegPerOp

public double estimateCostNegPerOp()

Description copied from interface: Ring

Estimates the number of negations (additive inversions) that can be done per group operation for the same cost. For example, 2 would mean that a negation costs half as much as a group operation, on average.

Specified by:

estimateCostNegPerOp in interface Ring

Returns:

estimated number of inversions that can be done per group operation for the same cost

sizeUnitGroup

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

Description copied from interface: Ring

Returns the number of units in this ring.

Specified by:

sizeUnitGroup in interface Ring

Returns:

size of the unit group or null if infinite

Throws:

java.lang.UnsupportedOperationException - if size is unknown or is computationally too expensive to compute

getZeroElement

public RingElement getZeroElement()

Description copied from interface: Ring

Returns the additive neutral element of this ring.

Specified by:

getZeroElement in interface Ring

getOneElement

public RingElement getOneElement()

Description copied from interface: Ring

Returns the multiplicative neutral element of this ring.

Specified by:

getOneElement in interface Ring

restoreElement

public RingElement restoreElement(Representation repr)

Description copied from interface: Structure

Creates an element of this structure from its representation.

Specified by:

restoreElement in interface Ring

Specified by:

restoreElement in interface Structure

Parameters:

repr - the Representation returned by Representable.getRepresentation()

Returns:

the decoded element corresponding to the representation

getUniqueByteLength

public java.util.Optional<java.lang.Integer> getUniqueByteLength()

Description copied from interface: Structure

Returns the number of bytes returned by this structure's UniqueByteRepresentable.getUniqueByteRepresentation(), or an empty Optional if this structure's elements do not guarantee a fixed length.

For example, elements of Zp will always be represented by ceil(ceil(log(p))/8) bytes, hence getUniqueByteLength() would return ceil(ceil(log(p))/8).

A polynomial ring would return an empty Optional since a polynomial's unique byte representation length depends on its degree.

Specified by:

getUniqueByteLength in interface Structure

Returns:

the guaranteed fixed length of getUniqueByteRepresentation(), or an empty Optional, if no guarantee

isCommutative

public boolean isCommutative()

Description copied from interface: Ring

Returns true if this ring is known to be commutative.

Specified by:

isCommutative in interface Ring

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

valueOf

public static ProductRingElement valueOf(RingElement... elems)

equals

public boolean equals(java.lang.Object other)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object