org.cryptimeleon.math.structures

Interface Structure

All Superinterfaces:

Representable, StandaloneRepresentable

All Known Subinterfaces:

Field, Group, Ring

All Known Implementing Classes:

BasicGroup, BooleanStructure, CountingGroup, ExtensionField, IntegerRing, LazyGroup, PolynomialRing, ProductGroup, ProductRing, RingGroup, Zn, Zp

public interface Structure
extends StandaloneRepresentable

Base interface for algebraic structures that contain elements.

Implementations should override equals() and hashCode().

Structures implement StandaloneRepresentable, i.e. they must supply a constructor with a single Representation argument. Hence, their Representation must contain all the information necessary to recreate the structure.

Method Summary

Modifier and Type	Method and Description
Element	getUniformlyRandomElement() Returns an element of this structure that is drawn uniformly at random using a cryptographically strong RNG.
Vector<? extends Element>	getUniformlyRandomElements(int n) Returns n elements of this structure that are drawn uniformly and independently 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.
default boolean	hasPrimeSize() Checks if the structure has prime size.
Element	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).

Methods inherited from interface org.cryptimeleon.math.serialization.Representable

getRepresentation

Method Detail

size

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

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

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

hasPrimeSize

default boolean hasPrimeSize()

Checks if the structure has prime size.

Returns:

true if the structure has prime size, else false.

Throws:

java.lang.UnsupportedOperationException - if the primality of the size cannot be determined

getUniformlyRandomElement

Element getUniformlyRandomElement()
                           throws java.lang.UnsupportedOperationException

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

Throws:

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

getUniformlyRandomElements

Vector<? extends Element> getUniformlyRandomElements(int n)
                                              throws java.lang.UnsupportedOperationException

Returns n elements of this structure that are drawn uniformly and independently at random using a cryptographically strong RNG.

Throws:

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

restoreElement

Element restoreElement(Representation repr)

Creates an element of this structure from its representation.

Parameters:

repr - the Representation returned by Representable.getRepresentation()

Returns:

the decoded element corresponding to the representation

getUniqueByteLength

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.

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.

Returns:

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