org.cryptimeleon.craco.commitment.hashthencommit

Class HashThenCommitCommitmentScheme

java.lang.Object

org.cryptimeleon.craco.commitment.hashthencommit.HashThenCommitCommitmentScheme

All Implemented Interfaces:

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

public class HashThenCommitCommitmentScheme
extends java.lang.Object
implements CommitmentScheme

Wrapper class that allows committing to the hash of a message.

Constructor Summary

Constructors

Constructor and Description
HashThenCommitCommitmentScheme(CommitmentScheme encapsulatedScheme, org.cryptimeleon.math.hash.HashFunction hashFunction) Constructor for HashThenCommitCommitmentScheme.
HashThenCommitCommitmentScheme(org.cryptimeleon.math.serialization.Representation repr) Constructor for a HashThenCommitCommitmentScheme-instance from a Representation.

Method Summary

Modifier and Type	Method and Description
CommitmentPair	commit(PlainText plainText) Returns a commitment to the hash of the given message, computed via the previously defined hash function.
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()
PlainText	mapToPlaintext(byte[] bytes) Provides an injective mapping of the given byte[] to a PlainText usable with this scheme (which may be a MessageBlock).
Commitment	restoreCommitment(org.cryptimeleon.math.serialization.Representation repr)
OpenValue	restoreOpenValue(org.cryptimeleon.math.serialization.Representation repr)
boolean	verify(Commitment commitment, OpenValue openValue, PlainText plainText) Verifies that the hash of the given announced PlainText equals the result of opening the Commitment with the OpenValue.

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

Constructor Detail

HashThenCommitCommitmentScheme

public HashThenCommitCommitmentScheme(CommitmentScheme encapsulatedScheme,
                                      org.cryptimeleon.math.hash.HashFunction hashFunction)

Constructor for HashThenCommitCommitmentScheme.

Parameters:

encapsulatedScheme - single-message-CommitmentScheme which shall be used in combination with a HashFunction

hashFunction - HashFunction used for hashing of the original message

HashThenCommitCommitmentScheme

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

Constructor for a HashThenCommitCommitmentScheme-instance from a Representation.

Parameters:

repr - Representation of a HashThenCommitCommitmentScheme instance

Method Detail

commit

public CommitmentPair commit(PlainText plainText)

Returns a commitment to the hash of the given message, computed via the previously defined hash function.

Specified by:

commit in interface CommitmentScheme

Parameters:

plainText - ByteArrayImplementation of the message to be hashed.

Returns:

commitment to the hashed input

verify

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

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

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

mapToPlaintext

public PlainText 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 Commitment restoreCommitment(org.cryptimeleon.math.serialization.Representation repr)

Specified by:

restoreCommitment in interface CommitmentScheme

restoreOpenValue

public OpenValue 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