org.cryptimeleon.craco.sig.sps.agho11

Class SPSAGHO11SignatureScheme

java.lang.Object

org.cryptimeleon.craco.sig.sps.agho11.SPSAGHO11SignatureScheme

All Implemented Interfaces:

MultiMessageSignatureScheme, MultiMessageStructurePreservingSignatureScheme, SignatureScheme, StandardMultiMessageSignatureScheme, StandardSignatureScheme, org.cryptimeleon.math.serialization.annotations.RepresentationRestorer, org.cryptimeleon.math.serialization.Representable, org.cryptimeleon.math.serialization.StandaloneRepresentable

public class SPSAGHO11SignatureScheme
extends java.lang.Object
implements MultiMessageStructurePreservingSignatureScheme

An implementation of the scheme originally presented in [1] [1] Abe et. al.: Optimal Structure-Preserving Signatures in Asymmetric Bilinear Groups. CRYPTO 2011: Advances in Cryptology – CRYPTO 2011 pp. 649-666 https://www.iacr.org/archive/crypto2011/68410646/68410646.pdf Note: To ensure the scheme's security as described in [1], messages and keys will be padded to length for short messages (k_M = 0 or k_N \in {0,1}), such that at least one G_1 group element and at least two G_2 groupElements are signed. The messages are assumed to be composed of a tuple of two MessageBlocks; one containing GroupElementPlainTexts of elements in G_1 and the other GroupElementPlainTexts of elements in G_2. The message vectors are padded with the neutral element of they respective groups. The key generation function accounts for this edge-case automatically by calculating the extra elements that are required as a consequence of the padding. From a user perspective, any positive length tuple of two message-vectors (M \in G_1,N \in G_2) may be passed without the need for additional precautions.

Field Summary

Fields

Modifier and Type	Field and Description
protected SPSAGHO11PublicParameters	pp The public parameters used by the scheme

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	SPSAGHO11SignatureScheme()
	SPSAGHO11SignatureScheme(org.cryptimeleon.math.serialization.Representation repr)
	SPSAGHO11SignatureScheme(SPSAGHO11PublicParameters pp)

Method Summary

Modifier and Type	Method and Description
boolean	equals(java.lang.Object o)
SignatureKeyPair<SPSAGHO11VerificationKey,SPSAGHO11SigningKey>	generateKeyPair(int... messageBlockLengths) Generates a key pair for signing n blocks of messages with messageBlockLengths with each signature.
SignatureKeyPair<SPSAGHO11VerificationKey,SPSAGHO11SigningKey>	generateKeyPair(int numberOfMessages) Generates a key pair for signing a block of numberOfMessages messages with each signature.
int	getMaxNumberOfBytesForMapToPlaintext() Returns the maximal number of bytes that can be mapped injectively to a PlainText by SignatureScheme.mapToPlaintext(byte[], SigningKey) and SignatureScheme.mapToPlaintext(byte[], VerificationKey).
org.cryptimeleon.math.serialization.Representation	getRepresentation()
int	hashCode()
MessageBlock	mapToPlaintext(byte[] bytes, SigningKey sk) Provides an injective mapping of the given bytes to a PlainText usable with this scheme (which may be a MessageBlock).
MessageBlock	mapToPlaintext(byte[] bytes, VerificationKey pk) Provides an injective mapping of the given bytes to a PlainText usable with this scheme (which may be a MessageBlock).
PlainText	restorePlainText(org.cryptimeleon.math.serialization.Representation repr)
Signature	restoreSignature(org.cryptimeleon.math.serialization.Representation repr)
SigningKey	restoreSigningKey(org.cryptimeleon.math.serialization.Representation repr)
VerificationKey	restoreVerificationKey(org.cryptimeleon.math.serialization.Representation repr)
Signature	sign(PlainText plainText, SigningKey secretKey) Signs the giving plaintext using the given signing key.
java.lang.Boolean	verify(PlainText plainText, Signature signature, VerificationKey publicKey) Verifies the given signature for the given plaintext using the given verification key.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.cryptimeleon.craco.sig.MultiMessageStructurePreservingSignatureScheme

sign, sign, verify, verify

Methods inherited from interface org.cryptimeleon.craco.sig.StandardMultiMessageSignatureScheme

generateKeyPair

Methods inherited from interface org.cryptimeleon.craco.sig.MultiMessageSignatureScheme

sign, sign, verify, verify

Methods inherited from interface org.cryptimeleon.craco.sig.SignatureScheme

restoreFromRepresentation, sign, verify

Field Detail

pp

protected SPSAGHO11PublicParameters pp

The public parameters used by the scheme

Constructor Detail

SPSAGHO11SignatureScheme

protected SPSAGHO11SignatureScheme()

SPSAGHO11SignatureScheme

public SPSAGHO11SignatureScheme(SPSAGHO11PublicParameters pp)

SPSAGHO11SignatureScheme

public SPSAGHO11SignatureScheme(org.cryptimeleon.math.serialization.Representation repr)

Method Detail

generateKeyPair

public SignatureKeyPair<SPSAGHO11VerificationKey,SPSAGHO11SigningKey> generateKeyPair(int numberOfMessages)

Description copied from interface: StandardMultiMessageSignatureScheme

Generates a key pair for signing a block of numberOfMessages messages with each signature.

Specified by:

generateKeyPair in interface StandardMultiMessageSignatureScheme

Parameters:

numberOfMessages - the number of messages as input to sign supported by this key pair

generateKeyPair

public SignatureKeyPair<SPSAGHO11VerificationKey,SPSAGHO11SigningKey> generateKeyPair(int... messageBlockLengths)

Generates a key pair for signing n blocks of messages with messageBlockLengths with each signature.

Parameters:

messageBlockLengths - the length of the individual MessageBlocks this scheme accepts as input.

sign

public Signature sign(PlainText plainText,
                      SigningKey secretKey)

Description copied from interface: SignatureScheme

Signs the giving plaintext using the given signing key. The signing key should contain all information necessary to sign, therefore public key is not needed.

Specified by:

sign in interface SignatureScheme

Parameters:

plainText - the message to sign

secretKey - the secret signing key

Returns:

signature on plainText computed using secretKey

verify

public java.lang.Boolean verify(PlainText plainText,
                                Signature signature,
                                VerificationKey publicKey)

Description copied from interface: SignatureScheme

Verifies the given signature for the given plaintext using the given verification key.

Specified by:

verify in interface SignatureScheme

Parameters:

plainText - the plaintext the signature should validate against

signature - the signature to verify

publicKey - the verification key to verify with

Returns:

true if verification succeeds, false else

restorePlainText

public PlainText restorePlainText(org.cryptimeleon.math.serialization.Representation repr)

Specified by:

restorePlainText in interface SignatureScheme

restoreSignature

public Signature restoreSignature(org.cryptimeleon.math.serialization.Representation repr)

Specified by:

restoreSignature in interface SignatureScheme

restoreSigningKey

public SigningKey restoreSigningKey(org.cryptimeleon.math.serialization.Representation repr)

Specified by:

restoreSigningKey in interface SignatureScheme

restoreVerificationKey

public VerificationKey restoreVerificationKey(org.cryptimeleon.math.serialization.Representation repr)

Specified by:

restoreVerificationKey in interface SignatureScheme

mapToPlaintext

public MessageBlock mapToPlaintext(byte[] bytes,
                                   VerificationKey pk)

Description copied from interface: SignatureScheme

Provides an injective mapping of the given bytes 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.

The contract is that VerificationKey pk and SigningKey sk are compatible (in the sense that verify(m,sign(m, sk),pk) == true), then mapToPlaintext(bytes, pk)) equals mapToPlaintext(bytes, sk) for all bytes.

Specified by:

mapToPlaintext in interface SignatureScheme

Parameters:

bytes - bytes to be mapped to a PlainText

pk - the verification key for which the resulting PlainText should be valid (note that the plaintext space may differ for different verification keys).

Returns:

the corresponding plaintext

mapToPlaintext

public MessageBlock mapToPlaintext(byte[] bytes,
                                   SigningKey sk)

Description copied from interface: SignatureScheme

Provides an injective mapping of the given bytes 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.

The contract is that VerificationKey pk and SigningKey sk are compatible (in the sense that verify(m,sign(m, sk),pk) == true), then mapToPlaintext(bytes, pk)) equals mapToPlaintext(bytes, sk) for all bytes.

Specified by:

mapToPlaintext in interface SignatureScheme

Parameters:

bytes - bytes to be mapped to a PlainText

sk - the signing key for which the resulting PlainText should be valid (note that the plaintext space may differ for different signing keys).

Returns:

the corresponding plaintext

getMaxNumberOfBytesForMapToPlaintext

public int getMaxNumberOfBytesForMapToPlaintext()

Description copied from interface: SignatureScheme

Returns the maximal number of bytes that can be mapped injectively to a PlainText by SignatureScheme.mapToPlaintext(byte[], SigningKey) and SignatureScheme.mapToPlaintext(byte[], VerificationKey).

As described in SignatureScheme.mapToPlaintext(byte[], org.cryptimeleon.craco.sig.VerificationKey) 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 SignatureScheme

Returns:

maximal number of bytes that can be given to SignatureScheme.mapToPlaintext(byte[], org.cryptimeleon.craco.sig.VerificationKey).

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