org.cryptimeleon.math.structures.groups.cartesian

Class ProductGroupElement

java.lang.Object

org.cryptimeleon.math.structures.groups.cartesian.ProductGroupElement

All Implemented Interfaces:

UniqueByteRepresentable, Representable, Element, GroupElement

public class ProductGroupElement
extends java.lang.Object
implements GroupElement

Field Summary

Fields

Modifier and Type	Field and Description
protected GroupElement[]	elems

Constructor Summary

Constructors

Constructor and Description
ProductGroupElement(GroupElement... elems)
ProductGroupElement(java.util.List<? extends GroupElement> elems)
ProductGroupElement(Representation repr)

Method Summary

Modifier and Type	Method and Description
GroupElementVector	asVector()
GroupElement	compute() Hint that the concrete value of this GroupElement will be accessed soon (e.g., via getRepresentation() or equals()).
GroupElement	computeSync() Will compute stuff synchronously (this call blocks) so that the next call requiring the concrete value of this group element can immediately retrieve it.
boolean	equals(java.lang.Object o)
GroupElement	get(int index)
Representation	getRepresentation() The representation of this object.
ProductGroup	getStructure() Returns the Structure that this Element belongs to.
int	hashCode()
ProductGroupElement	inv() Calculates the inverse of this group element.
boolean	isComputed() Returns true if a concrete value has already been computed.
ProductGroupElement	op(Element e) Calculates the result of this.op(e).
ProductGroupElement	pow(java.math.BigInteger k) Calculates the result of applying the group operation k times.
GroupElement	precomputePow(int windowSize) Advises the GroupElement to prepare it for later pow() calls.
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, toString, wait, wait, wait

Methods inherited from interface org.cryptimeleon.math.structures.groups.GroupElement

expr, isEqualTo, isEqualTo, isEqualTo, isNeutralElement, op, op, pow, pow, pow, pow, pow, pow, precomputePow, square

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

getUniqueByteRepresentation

Field Detail

elems

protected GroupElement[] elems

Constructor Detail

ProductGroupElement

public ProductGroupElement(java.util.List<? extends GroupElement> elems)

ProductGroupElement

public ProductGroupElement(GroupElement... elems)

ProductGroupElement

public ProductGroupElement(Representation repr)

Method Detail

getStructure

public ProductGroup 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 GroupElement

inv

public ProductGroupElement inv()

Description copied from interface: GroupElement

Calculates the inverse of this group element.

Specified by:

inv in interface GroupElement

Returns:

an element x such that x.op(this).equals(getStructure().getNeutralElement())

op

public ProductGroupElement op(Element e)
                       throws java.lang.IllegalArgumentException

Description copied from interface: GroupElement

Calculates the result of this.op(e).

Specified by:

op in interface GroupElement

Parameters:

e - right hand side of the operation

Returns:

the element resulting from the group operation

Throws:

java.lang.IllegalArgumentException - if e is of the wrong type

pow

public ProductGroupElement pow(java.math.BigInteger k)

Description copied from interface: GroupElement

Calculates the result of applying the group operation k times. i.e. it computes k*this (additive group) or this^k (multiplicative group). For negative exponents k, computes this.inv().pow(-k).

Specified by:

pow in interface GroupElement

precomputePow

public GroupElement precomputePow(int windowSize)

Description copied from interface: GroupElement

Advises the GroupElement to prepare it for later pow() calls. This will take some time and should only be done ahead of time. That is, the usual usage pattern should be:

 //Setting up your encryption scheme (or whatever)
 GroupElement g = group.getUniformlyRandomElement().precomputePow();
 //Then (maybe even multiple) future calls of
 GroupElement encrypt(GroupElement m) {
     return m.op(g.pow(sk)).compute();
 }
 

Don't use g.precomputePow().pow(x).compute(); unless you're planning to do more exponentiations of g in the future.

Specified by:

precomputePow in interface GroupElement

Parameters:

windowSize - an indicator for how much memory you're willing to invest. Precomputation will take up space of roughly 2^(windowSize) group elements.

Returns:

the same object (for chaining calls)

compute

public GroupElement compute()

Description copied from interface: GroupElement

Hint that the concrete value of this GroupElement will be accessed soon (e.g., via getRepresentation() or equals()). Will start computing stuff in the background.

Specified by:

compute in interface GroupElement

Returns:

the same object (for chaining calls)

computeSync

public GroupElement computeSync()

Description copied from interface: GroupElement

Will compute stuff synchronously (this call blocks) so that the next call requiring the concrete value of this group element can immediately retrieve it. For designers of cryptographic schemes, were should be no reason to call this. Instead, use compute() which does the same, but asynchronously (i.e. concurrently).

Specified by:

computeSync in interface GroupElement

Returns:

the same object (for chaining calls)

isComputed

public boolean isComputed()

Description copied from interface: GroupElement

Returns true if a concrete value has already been computed. No need to call this outside of upb.crypto.math, it's meant to allow for optimizations.

Specified by:

isComputed in interface GroupElement

get

public GroupElement get(int index)

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

asVector

public GroupElementVector asVector()

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

equals

public boolean equals(java.lang.Object o)

Specified by:

equals in interface Element

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Specified by:

hashCode in interface Element

Overrides:

hashCode in class java.lang.Object