org.cryptimeleon.math.structures.groups.counting

Class CountingBilinearMapImpl

java.lang.Object

org.cryptimeleon.math.structures.groups.counting.CountingBilinearMapImpl

All Implemented Interfaces:

java.util.function.BiFunction<GroupElementImpl,GroupElementImpl,GroupElementImpl>, BilinearMapImpl

public class CountingBilinearMapImpl
extends java.lang.Object
implements BilinearMapImpl

A BilinearMapImpl implementing a fast, but insecure pairing over Zn. Allows for counting pairings.

The bilinear map works by mapping (Zn,+) x (Zn,+) to (Zn,+) via (a,b) -> a*b (multiplication in Zn). It is insecure since DLOG is trivial in Zn.

Field Summary

Fields

Modifier and Type	Field and Description
protected CountingGroupImpl	g1 The groups underlying the bilinear group.
protected CountingGroupImpl	g2 The groups underlying the bilinear group.
protected CountingGroupImpl	gt The groups underlying the bilinear group.
protected long	numPairings The counted number of pairings.
protected BilinearGroup.Type	pairingType The type of pairing this bilinear map offers.
protected java.math.BigInteger	size The order of the bilinear group.
protected Zn	zn Zn of order the bilinear group's size.

Constructor Summary

Constructors

Constructor and Description
CountingBilinearMapImpl(BilinearGroup.Type type, java.math.BigInteger groupSize, boolean enableExpCounting, boolean enableMultiExpCounting) Instantiates this bilinear map with the given pairing type, group size, and counting configuration.

Method Summary

Modifier and Type	Method and Description
GroupElementImpl	apply(GroupElementImpl g1, GroupElementImpl g2) Corresponds to this.apply(g1, g2, 1).
GroupElementImpl	apply(GroupElementImpl g1, GroupElementImpl g2, java.math.BigInteger exponent) Computes \(e(g1,g2)^\text{exponent}\).
boolean	equals(java.lang.Object o)
long	getNumPairings() Retrieves number of pairings computed in this bilinear group.
int	hashCode()
protected void	incrementNumPairings() Increments the pairing counter.
boolean	isSymmetric() Returns true if \(e(g,h) = e(h,g)\) for all g in G1, h in G2.
void	resetNumPairings() Resets pairing counter.
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.function.BiFunction

andThen

Field Detail

g1

protected CountingGroupImpl g1

The groups underlying the bilinear group.

g2

protected CountingGroupImpl g2

The groups underlying the bilinear group.

gt

protected CountingGroupImpl gt

The groups underlying the bilinear group.

zn

protected Zn zn

Zn of order the bilinear group's size.

size

protected java.math.BigInteger size

The order of the bilinear group.

pairingType

protected BilinearGroup.Type pairingType

The type of pairing this bilinear map offers.

numPairings

protected long numPairings

The counted number of pairings.

Constructor Detail

CountingBilinearMapImpl

public CountingBilinearMapImpl(BilinearGroup.Type type,
                               java.math.BigInteger groupSize,
                               boolean enableExpCounting,
                               boolean enableMultiExpCounting)

Instantiates this bilinear map with the given pairing type, group size, and counting configuration.

Parameters:

type - type of the pairing

groupSize - size of g1, g2, and gt (number of group elements)

enableExpCounting - if true, exponentiations in G1, G2 and GT are counted as a single unit and group operations within exponentiations are not counted; otherwise the former is not done and group operations within exponentiations are added to the total count

enableMultiExpCounting - if true, number of terms in each multi-exponentiation is tracked and group operations within multi-exponentiations are not counted; otherwise the former is not done and group operations within multi-exponentiations are added to the total count

Method Detail

apply

public GroupElementImpl apply(GroupElementImpl g1,
                              GroupElementImpl g2,
                              java.math.BigInteger exponent)

Description copied from interface: BilinearMapImpl

Computes \(e(g1,g2)^\text{exponent}\).

Depending on the bilinear map and the involved groups, this may be more efficiently implemented than computing it directly via apply(g1,g2).pow(exponent). For example, implementations should do exponentiation in the group with the cheapest group operation.

Specified by:

apply in interface BilinearMapImpl

Parameters:

g1 - left hand side argument for the pairing function

g2 - right hand side argument for the pairing function

exponent - the exponent to apply to the result of the pairing

apply

public GroupElementImpl apply(GroupElementImpl g1,
                              GroupElementImpl g2)

Description copied from interface: BilinearMapImpl

Corresponds to this.apply(g1, g2, 1).

Specified by:

apply in interface java.util.function.BiFunction<GroupElementImpl,GroupElementImpl,GroupElementImpl>

Specified by:

apply in interface BilinearMapImpl

Parameters:

g1 - left hand side argument for the pairing function

g2 - right hand side argument for the pairing function

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

isSymmetric

public boolean isSymmetric()

Description copied from interface: BilinearMapImpl

Returns true if \(e(g,h) = e(h,g)\) for all g in G1, h in G2.

Specified by:

isSymmetric in interface BilinearMapImpl

equals

public boolean equals(java.lang.Object o)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

getNumPairings

public long getNumPairings()

Retrieves number of pairings computed in this bilinear group.

resetNumPairings

public void resetNumPairings()

Resets pairing counter.

incrementNumPairings

protected void incrementNumPairings()

Increments the pairing counter.