org.cryptimeleon.craco.commitment.pedersen

Class PedersenCommitmentScheme

java.lang.Object

org.cryptimeleon.craco.commitment.pedersen.PedersenCommitmentScheme

All Implemented Interfaces:

CommitmentScheme, org.cryptimeleon.math.serialization.annotations.RepresentationRestorer, org.cryptimeleon.math.serialization.Representable, org.cryptimeleon.math.serialization.StandaloneRepresentable

public class PedersenCommitmentScheme
extends java.lang.Object
implements CommitmentScheme

This class provides a java implementation for the Pedersen commitment scheme. It realizes the general CommitmentScheme interface and provides a concrete Pedersen commitment scheme implementation for (commit, open) methods.

Field Summary

Fields

Modifier and Type	Field and Description
protected org.cryptimeleon.math.structures.groups.GroupElement	g
protected org.cryptimeleon.math.structures.groups.Group	group
protected org.cryptimeleon.math.structures.groups.cartesian.GroupElementVector	h

Constructor Summary

Constructors

Constructor and Description
PedersenCommitmentScheme(org.cryptimeleon.math.structures.groups.Group group, org.cryptimeleon.math.structures.groups.GroupElement g, org.cryptimeleon.math.structures.groups.cartesian.GroupElementVector h)
PedersenCommitmentScheme(org.cryptimeleon.math.structures.groups.Group group, int numMessages)
PedersenCommitmentScheme(org.cryptimeleon.math.serialization.Representation repr)

Method Summary

Modifier and Type	Method and Description
CommitmentPair	commit(PlainText plainText) Creates a commitment to the given PlainText.
CommitmentPair	commit(org.cryptimeleon.math.structures.rings.cartesian.RingElementVector valuesToCommit)
CommitmentPair	commit(org.cryptimeleon.math.structures.rings.cartesian.RingElementVector valuesToCommit, org.cryptimeleon.math.structures.rings.zn.Zn.ZnElement randomness)
CommitmentPair	commit(org.cryptimeleon.math.structures.rings.zn.Zn.ZnElement... valuesToCommit)
boolean	equals(java.lang.Object o)
int	getMaxNumberOfBytesForMapToPlaintext() Returns the maximal number of bytes that can be mapped injectively to a PlainText by CommitmentScheme.mapToPlaintext(byte[])
org.cryptimeleon.math.serialization.Representation	getRepresentation()
int	hashCode()
MessageBlock	mapToPlaintext(byte[] bytes) Provides an injective mapping of the given byte[] to a PlainText usable with this scheme (which may be a MessageBlock).
PedersenCommitment	restoreCommitment(org.cryptimeleon.math.serialization.Representation repr)
PedersenOpenValue	restoreOpenValue(org.cryptimeleon.math.serialization.Representation repr)
boolean	verify(Commitment commitment, OpenValue openValue, PlainText plainText) Verifies that the given announced PlainText equals the result of opening the Commitment with the OpenValue.
boolean	verify(Commitment commitment, OpenValue openValue, org.cryptimeleon.math.structures.rings.cartesian.RingElementVector committedValues)

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.cryptimeleon.craco.commitment.CommitmentScheme

restoreCommitmentPair, restoreFromRepresentation

Field Detail

group

protected org.cryptimeleon.math.structures.groups.Group group

h

protected org.cryptimeleon.math.structures.groups.cartesian.GroupElementVector h

g

protected org.cryptimeleon.math.structures.groups.GroupElement g

Constructor Detail

PedersenCommitmentScheme

public PedersenCommitmentScheme(org.cryptimeleon.math.serialization.Representation repr)

PedersenCommitmentScheme

public PedersenCommitmentScheme(org.cryptimeleon.math.structures.groups.Group group,
                                org.cryptimeleon.math.structures.groups.GroupElement g,
                                org.cryptimeleon.math.structures.groups.cartesian.GroupElementVector h)

PedersenCommitmentScheme

public PedersenCommitmentScheme(org.cryptimeleon.math.structures.groups.Group group,
                                int numMessages)

Method Detail

commit

public CommitmentPair commit(PlainText plainText)

Description copied from interface: CommitmentScheme

Creates a commitment to the given PlainText.

Specified by:

commit in interface CommitmentScheme

Parameters:

plainText - the message to commit to

Returns:

the CommitmentPair containing the commitment and an OpenValue that can be used to reveal the committed message.

commit

public CommitmentPair commit(org.cryptimeleon.math.structures.rings.zn.Zn.ZnElement... valuesToCommit)

commit

public CommitmentPair commit(org.cryptimeleon.math.structures.rings.cartesian.RingElementVector valuesToCommit)

commit

public CommitmentPair commit(org.cryptimeleon.math.structures.rings.cartesian.RingElementVector valuesToCommit,
                             org.cryptimeleon.math.structures.rings.zn.Zn.ZnElement randomness)

verify

public boolean verify(Commitment commitment,
                      OpenValue openValue,
                      PlainText plainText)

Description copied from interface: CommitmentScheme

Verifies that the given announced PlainText equals the result of opening the Commitment with the OpenValue.

A commitment scheme such as HashThenCommitCommitmentScheme may also hash the message before committing to it. This method can take this into account, i.e. by hashing the given announced plaintext before comparing.

Specified by:

verify in interface CommitmentScheme

Parameters:

commitment - commitment to verify

openValue - used to open the commitment and reveal the content

plainText - the hash of this will be compared with the opened commitment message

Returns:

true if verification succeeds, else false

verify

public boolean verify(Commitment commitment,
                      OpenValue openValue,
                      org.cryptimeleon.math.structures.rings.cartesian.RingElementVector committedValues)

mapToPlaintext

public MessageBlock mapToPlaintext(byte[] bytes)
                            throws java.lang.IllegalArgumentException

Description copied from interface: CommitmentScheme

Provides an injective mapping of the given byte[] to a PlainText usable with this scheme (which may be a MessageBlock). It only guarantees injectivity for arrays of the same length. Applications that would like to use mapToPlaintext with multiple different array lengths may want to devise a padding method and then only call mapToPlaintext with byte arrays of the same (padded) length.

Specified by:

mapToPlaintext in interface CommitmentScheme

Parameters:

bytes - byte[] to map to a PlainText that can be committed to using this commitment scheme

Returns:

PlainText usable with this commitment scheme

Throws:

java.lang.IllegalArgumentException - if there is no injective PlainText element corresponding to the given bytes, for example if the byte array is too long

getMaxNumberOfBytesForMapToPlaintext

public int getMaxNumberOfBytesForMapToPlaintext()

Description copied from interface: CommitmentScheme

Returns the maximal number of bytes that can be mapped injectively to a PlainText by CommitmentScheme.mapToPlaintext(byte[])

As described in CommitmentScheme.mapToPlaintext(byte[]) there might be no injective PlainText for some byte arrays, e.g. if the byte array is too long. Therefore, this method provides the maximal number of bytes that can be mapped injectively to a PlainText.

Specified by:

getMaxNumberOfBytesForMapToPlaintext in interface CommitmentScheme

Returns:

maximal number of bytes that can be given to CommitmentScheme.mapToPlaintext(byte[]).

restoreCommitment

public PedersenCommitment restoreCommitment(org.cryptimeleon.math.serialization.Representation repr)

Specified by:

restoreCommitment in interface CommitmentScheme

restoreOpenValue

public PedersenOpenValue restoreOpenValue(org.cryptimeleon.math.serialization.Representation repr)

Specified by:

restoreOpenValue in interface CommitmentScheme

getRepresentation

public org.cryptimeleon.math.serialization.Representation getRepresentation()

Specified by:

getRepresentation in interface org.cryptimeleon.math.serialization.Representable

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