org.cryptimeleon.math.structures.groups.debug

Class DebugGroupImpl

java.lang.Object

org.cryptimeleon.math.structures.groups.debug.DebugGroupImpl

All Implemented Interfaces:

RepresentationRestorer, Representable, StandaloneRepresentable, GroupImpl

Direct Known Subclasses:

DebugGroupImplNoExpMultiExp, DebugGroupImplTotal

public abstract class DebugGroupImpl
extends java.lang.Object
implements GroupImpl

Zn-based group that supports counting group operationsinversionssquarings and exponentiations as well as number of terms in each multi-exponentiation.

Field Summary

Fields

Modifier and Type	Field and Description
protected java.lang.String	name Name of this group.
protected Zn	zn The Zn underlying this group.

Constructor Summary

Constructors

Constructor and Description
DebugGroupImpl(Representation repr)
DebugGroupImpl(java.lang.String name, java.math.BigInteger n) Instantiates this group with the given name and group size and to not count (multi-)exponentiations explicitly (instead only total group operations are counted).

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.
GroupElementImpl	getGenerator() Returns any generator of this group if the group is cyclic and it's feasible to compute a generator.
GroupElementImpl	getNeutralElement() Returns the neutral element of this group.
Representation	getRepresentation() The representation of this object.
GroupElementImpl	getUniformlyRandomElement() Generates a uniformly random element of this group.
GroupElementImpl	getUniformlyRandomNonNeutral() Generates a uniformly random non-neutral element of this group.
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.
int	hashCode()
boolean	hasPrimeSize() Returns true if the size of this structure is known and prime.
boolean	isCommutative() Returns true if this group is known to be commutative.
GroupElementImpl	restoreElement(Representation repr) Restores a group element from its representation.
java.math.BigInteger	size() Retrieves number of elements in the group if possible.
java.lang.String	toString()
DebugGroupElementImpl	wrap(Zn.ZnElement elem) Wraps a ZnElement in a CountingGroupElementImpl belonging to this group.

Methods inherited from class java.lang.Object

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

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

exp, implementsOwnExp, implementsOwnMultiExp, multiexp, restoreFromRepresentation

Field Detail

name

protected java.lang.String name

Name of this group. Group elements between CountingGroupElementImpl instances only allow for group operations if the groups' names match.

zn

protected Zn zn

The Zn underlying this group. Realizes the actual group operations.

Constructor Detail

DebugGroupImpl

public DebugGroupImpl(java.lang.String name,
                      java.math.BigInteger n)

Instantiates this group with the given name and group size and to not count (multi-)exponentiations explicitly (instead only total group operations are counted).

Parameters:

name - a unique name for this group. group operations are only compatible between groups of the same name and n

n - the size of this group

DebugGroupImpl

public DebugGroupImpl(Representation repr)

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

getNeutralElement

public GroupElementImpl getNeutralElement()

Description copied from interface: GroupImpl

Returns the neutral element of this group.

Specified by:

getNeutralElement in interface GroupImpl

getUniformlyRandomElement

public GroupElementImpl getUniformlyRandomElement()
                                           throws java.lang.UnsupportedOperationException

Description copied from interface: GroupImpl

Generates a uniformly random element of this group.

Specified by:

getUniformlyRandomElement in interface GroupImpl

Throws:

java.lang.UnsupportedOperationException - if the random generation cannot be done

getUniformlyRandomNonNeutral

public GroupElementImpl getUniformlyRandomNonNeutral()
                                              throws java.lang.UnsupportedOperationException

Description copied from interface: GroupImpl

Generates a uniformly random non-neutral element of this group.

Specified by:

getUniformlyRandomNonNeutral in interface GroupImpl

Throws:

java.lang.UnsupportedOperationException - if the random generation cannot be done

restoreElement

public GroupElementImpl restoreElement(Representation repr)

Description copied from interface: GroupImpl

Restores a group element from its representation.

Specified by:

restoreElement in interface GroupImpl

getGenerator

public GroupElementImpl getGenerator()
                              throws java.lang.UnsupportedOperationException

Description copied from interface: GroupImpl

Returns any generator of this group if the group is cyclic and it's feasible to compute a generator.

Repeated calls may or may not always supply the same generator again (i.e. the output is not guaranteed to be random)!

Specified by:

getGenerator in interface GroupImpl

Throws:

java.lang.UnsupportedOperationException - if group is not cyclic or it's too hard to compute a generator

getUniqueByteLength

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

Description copied from interface: GroupImpl

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 GroupImpl

Returns:

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

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(java.lang.Object other)

Overrides:

equals in class java.lang.Object

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

isCommutative

public boolean isCommutative()

Description copied from interface: GroupImpl

Returns true if this group is known to be commutative.

Specified by:

isCommutative in interface GroupImpl

size

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

Description copied from interface: GroupImpl

Retrieves number of elements in the group if possible.

Specified by:

size in interface GroupImpl

Returns:

size of this group (number of group elements in it) or null if infinite

Throws:

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

hasPrimeSize

public boolean hasPrimeSize()
                     throws java.lang.UnsupportedOperationException

Description copied from interface: GroupImpl

Returns true if the size of this structure is known and prime.

Specified by:

hasPrimeSize in interface GroupImpl

Throws:

java.lang.UnsupportedOperationException

wrap

public DebugGroupElementImpl wrap(Zn.ZnElement elem)

Wraps a ZnElement in a CountingGroupElementImpl belonging to this group.

estimateCostInvPerOp

public double estimateCostInvPerOp()

Description copied from interface: GroupImpl

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 GroupImpl

Returns:

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