org.cryptimeleon.craco.sig

Interface StructurePreservingSignatureEQScheme

All Superinterfaces:

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

All Known Implementing Classes:

SPSEQSignatureScheme

public interface StructurePreservingSignatureEQScheme
extends StandardMultiMessageSignatureScheme

A structure-preserving signature scheme on equivalence classes (SPS-EQ).

This is a special case of a multi-message signature scheme because SPS-EQ additionally supports a change of the representative of the equivalence class that is signed.

See paper [1] for the definition of SPS-EQ.

[1] Georg Fuchsbauer and Christian Hanser and Daniel Slamanig, "Structure-Preserving Signatures on Equivalence Classes and Constant-Size Anonymous Credentials", in Cryptology ePrint Archive, Report 2014/944, 2014.

Method Summary

Modifier and Type	Method and Description
Signature	chgRep(Signature signature, org.cryptimeleon.math.structures.rings.zn.Zn.ZnElement mu, VerificationKey publicKey) Returns a signature for the new representative computed based on the previous representative and the given scalar mu.
PlainText	chgRepMessage(PlainText plainText, org.cryptimeleon.math.structures.rings.zn.Zn.ZnElement mu) Computes and returns the new representative computed based on the previous representative plainText and the given scalar mu.
Signature	chgRepWithVerify(PlainText plainText, Signature signature, org.cryptimeleon.math.structures.rings.zn.Zn.ZnElement mu, VerificationKey publicKey) Same as chgRep(Signature, Zn.ZnElement, VerificationKey) but verifies the signature before changing representative.
default Signature	sign(SigningKey secretKey, org.cryptimeleon.math.structures.groups.GroupElement... groupElements) Signs multiple group elements as a single unit.
default Signature	sign(SigningKey secretKey, org.cryptimeleon.math.structures.groups.cartesian.GroupElementVector groupElements) Signs the given vector of group elements.
default java.lang.Boolean	verify(VerificationKey verificationKey, Signature signature, org.cryptimeleon.math.structures.groups.GroupElement... groupElements) Verifies a signature for multiple messages.
default java.lang.Boolean	verify(VerificationKey verificationKey, Signature signature, org.cryptimeleon.math.structures.groups.cartesian.GroupElementVector groupElements) Verifies a signature for a vector of group elements.

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

generateKeyPair, generateKeyPair

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

sign, sign, verify, verify

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

getMaxNumberOfBytesForMapToPlaintext, mapToPlaintext, mapToPlaintext, restoreFromRepresentation, restorePlainText, restoreSignature, restoreSigningKey, restoreVerificationKey, sign, sign, verify, verify

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

getRepresentation

Method Detail

chgRep

Signature chgRep(Signature signature,
                 org.cryptimeleon.math.structures.rings.zn.Zn.ZnElement mu,
                 VerificationKey publicKey)

Returns a signature for the new representative computed based on the previous representative and the given scalar mu.

If you have not yet verified the signature on the plaintext under the given verification key, use chgRepWithVerify(PlainText, Signature, Zn.ZnElement, VerificationKey) instead.

This method returns a signature matching the new representative of \([M]_R\), where \(M\) is the orignal plaintext. The new representative of \([M]_R\) is supposed to be generated externally by using \(M\) and element \(\mu\). The matching signature \(\sigma'\) for the new representative \(\mu \cdot M\) of \([M]_R\) is computed such that verify(M.pow(), sigma') == true.

See paper [1] for details.

Returns:

a new valid signature on the new representative

chgRepWithVerify

Signature chgRepWithVerify(PlainText plainText,
                           Signature signature,
                           org.cryptimeleon.math.structures.rings.zn.Zn.ZnElement mu,
                           VerificationKey publicKey)

Same as chgRep(Signature, Zn.ZnElement, VerificationKey) but verifies the signature before changing representative.

Returns:

null if the given signature is not valid for plainText under publicKey, else a valid signature on the new representative

See Also:

chgRep(Signature, Zn.ZnElement, VerificationKey)

chgRepMessage

PlainText chgRepMessage(PlainText plainText,
                        org.cryptimeleon.math.structures.rings.zn.Zn.ZnElement mu)

Computes and returns the new representative computed based on the previous representative plainText and the given scalar mu.

sign

default Signature sign(SigningKey secretKey,
                       org.cryptimeleon.math.structures.groups.GroupElement... groupElements)

Signs multiple group elements as a single unit.

Parameters:

secretKey - key to sign with

groupElements - group elements to sign

Returns:

signature over the given plaintexts

verify

default java.lang.Boolean verify(VerificationKey verificationKey,
                                 Signature signature,
                                 org.cryptimeleon.math.structures.groups.GroupElement... groupElements)

Verifies a signature for multiple messages.

Parameters:

verificationKey - key to use for verification

signature - signature to verify

groupElements - group elements to verify signature for

Returns:

true if verification succeeds, else false

sign

default Signature sign(SigningKey secretKey,
                       org.cryptimeleon.math.structures.groups.cartesian.GroupElementVector groupElements)

Signs the given vector of group elements.

Parameters:

secretKey - key to sign with

groupElements - vector of group elements to sign

Returns:

signature over the given vector of plaintexts

verify

default java.lang.Boolean verify(VerificationKey verificationKey,
                                 Signature signature,
                                 org.cryptimeleon.math.structures.groups.cartesian.GroupElementVector groupElements)

Verifies a signature for a vector of group elements.

Parameters:

verificationKey - key to use for verification

signature - signature to verify

groupElements - vector of group elements to verify signature for

Returns:

true if verification succeeds, else false