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Merge pull request #77 from cryptimeleon/feature/dsprotection-refacto…
…ring First version of double-spending protection service ready for review
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crypto/src/main/java/org/cryptimeleon/incentive/crypto/Helper.java
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| package org.cryptimeleon.incentive.crypto; | ||
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| import org.cryptimeleon.craco.sig.sps.eq.SPSEQSignature; | ||
| import org.cryptimeleon.incentive.crypto.model.*; | ||
| import org.cryptimeleon.incentive.crypto.model.keys.provider.ProviderKeyPair; | ||
| import org.cryptimeleon.incentive.crypto.model.keys.user.UserKeyPair; | ||
| import org.cryptimeleon.incentive.crypto.model.keys.user.UserPublicKey; | ||
| import org.cryptimeleon.incentive.crypto.proof.spend.leaf.TokenPointsLeaf; | ||
| import org.cryptimeleon.incentive.crypto.proof.spend.leaf.TokenUpdateLeaf; | ||
| import org.cryptimeleon.incentive.crypto.proof.spend.tree.SpendDeductAndNode; | ||
| import org.cryptimeleon.incentive.crypto.proof.spend.tree.SpendDeductTree; | ||
| import org.cryptimeleon.math.serialization.Representable; | ||
| import org.cryptimeleon.math.serialization.converter.JSONConverter; | ||
| import org.cryptimeleon.math.structures.cartesian.Vector; | ||
| import org.cryptimeleon.math.structures.groups.Group; | ||
| import org.cryptimeleon.math.structures.rings.cartesian.RingElementVector; | ||
| import org.cryptimeleon.math.structures.rings.zn.Zn; | ||
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|
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| import java.math.BigInteger; | ||
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| /** | ||
| * Class that creates some random mathematic objects. Used to shorten tests and sometimes system code. | ||
| */ | ||
| public class Helper { | ||
| /** | ||
| * Generates a sound empty (i.e. no points) user token as output by a sound execution of the Issue-Join protocol. | ||
| */ | ||
| public static Token generateToken(IncentivePublicParameters pp, | ||
| UserKeyPair userKeyPair, | ||
| ProviderKeyPair providerKeyPair, | ||
| PromotionParameters promotionParameters) { | ||
| return generateToken(pp, | ||
| userKeyPair, | ||
| providerKeyPair, | ||
| promotionParameters, | ||
| Vector.iterate(BigInteger.valueOf(0), v -> v, promotionParameters.getPointsVectorSize())); | ||
| } | ||
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|
||
| /** | ||
| * Generates a valid user token, as output by a sound execution of the Issue-Join protocol followed by an execution of Credit-Earn with the passed earn vector. | ||
| */ | ||
| public static Token generateToken(IncentivePublicParameters pp, | ||
| UserKeyPair userKeyPair, | ||
| ProviderKeyPair providerKeyPair, | ||
| PromotionParameters promotionParameters, | ||
| Vector<BigInteger> points) { | ||
| var vectorH = providerKeyPair.getPk().getH(pp, promotionParameters); | ||
| var zp = pp.getBg().getZn(); | ||
| // Manually create a token since issue-join is not yet implemented | ||
| var encryptionSecretKey = zp.getUniformlyRandomNonzeroElement(); | ||
| var dsrd1 = zp.getUniformlyRandomElement(); | ||
| var dsrd2 = zp.getUniformlyRandomElement(); | ||
| var z = zp.getUniformlyRandomElement(); | ||
| var t = zp.getUniformlyRandomElement(); | ||
| var pointsVector = RingElementVector.fromStream(points.stream().map(e -> pp.getBg().getZn().createZnElement(e))); | ||
| var exponents = RingElementVector.of( | ||
| t, userKeyPair.getSk().getUsk(), encryptionSecretKey, dsrd1, dsrd2, z | ||
| ); | ||
| exponents = exponents.concatenate(pointsVector); | ||
| var c1 = vectorH.innerProduct(exponents).compute(); | ||
| var c2 = pp.getG1Generator(); | ||
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||
| return new Token( | ||
| c1, | ||
| c2, | ||
| encryptionSecretKey, | ||
| dsrd1, | ||
| dsrd2, | ||
| z, | ||
| t, | ||
| promotionParameters.getPromotionId(), | ||
| pointsVector, | ||
| (SPSEQSignature) pp.getSpsEq().sign( | ||
| providerKeyPair.getSk().getSkSpsEq(), | ||
| c1, | ||
| c2, | ||
| c2.pow(promotionParameters.getPromotionId()) | ||
| ) | ||
| ); | ||
| } | ||
|
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||
| /** | ||
| * Generates a sound transaction that spends the passed token. | ||
| * | ||
| * @return spend-deduct output, consisting of this transaction and the result token | ||
| */ | ||
| public static SpendDeductOutput generateSoundTransaction(IncentiveSystem incSys, | ||
| PromotionParameters promP, | ||
| Token token, | ||
| ProviderKeyPair pkp, | ||
| UserKeyPair ukp, | ||
| Vector<BigInteger> newPoints, | ||
| Zn.ZnElement tid, | ||
| SpendDeductTree spendDeductTree | ||
| ) { | ||
| var spendRequest = incSys.generateSpendRequest(promP, token, pkp.getPk(), newPoints, ukp, tid, spendDeductTree); | ||
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| var deductOutput = incSys.generateSpendRequestResponse(promP, spendRequest, pkp, tid, spendDeductTree); | ||
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| var resultToken = incSys.handleSpendRequestResponse(promP, deductOutput.getSpendResponse(), spendRequest, token, newPoints, pkp.getPk(), ukp); | ||
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| var occuredTransaction = new Transaction( | ||
| true, | ||
| tid, | ||
| token.getPoints().get(0).asInteger().subtract(newPoints.get(0)), // for v1: difference in 0-th component taken as spend amount TODO make transaction API able to handle vectors | ||
| deductOutput.getDstag() | ||
| ); | ||
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| return new SpendDeductOutput(resultToken, occuredTransaction); | ||
| } | ||
|
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| /** | ||
| * Creates and returns a transaction with spend amount 1 and random other fields. | ||
| * | ||
| * @param valid whether the generated transaction shall be valid or not | ||
| */ | ||
| // TODO: make spend amount random once basket server endpoint is implemented | ||
| public static Transaction generateRandomTransaction(IncentivePublicParameters pp, boolean valid) { | ||
| Zn usedZn = pp.getBg().getZn(); | ||
| Group usedG1 = pp.getBg().getG1(); | ||
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| return new Transaction( | ||
| valid, | ||
| usedZn.getUniformlyRandomElement(), | ||
| BigInteger.ONE, | ||
| new DoubleSpendingTag( | ||
| usedZn.getUniformlyRandomElement(), | ||
| usedZn.getUniformlyRandomElement(), | ||
| usedZn.getUniformlyRandomElement(), | ||
| usedZn.getUniformlyRandomElement(), | ||
| usedG1.getUniformlyRandomElements(pp.getNumEskDigits()), | ||
| usedG1.getUniformlyRandomElements(pp.getNumEskDigits()) | ||
| ) | ||
| ); | ||
| } | ||
|
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||
| /** | ||
| * Creates random user info. | ||
| * | ||
| * @return UserInfo | ||
| */ | ||
| public static UserInfo generateRandomUserInfo(IncentivePublicParameters pp) { | ||
| Zn usedZn = pp.getBg().getZn(); | ||
| Group usedG1 = pp.getBg().getG1(); | ||
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| return new UserInfo( | ||
| new UserPublicKey(usedG1.getUniformlyRandomElement()), | ||
| usedZn.getUniformlyRandomElement(), | ||
| usedZn.getUniformlyRandomElement() | ||
| ); | ||
| } | ||
|
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||
| /** | ||
| * Helper method to shorten code, returns a serialized representation of the passed representable. | ||
| */ | ||
| public static String computeSerializedRepresentation(Representable r) { | ||
| JSONConverter jsonConverter = new JSONConverter(); | ||
| return jsonConverter.serialize( | ||
| r.getRepresentation() | ||
| ); | ||
| } | ||
|
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| /** | ||
| * Helper that generates a simple SpendDeductTree which represents a ZKP that checks whether there are enough points | ||
| * to spend and then spends the points. | ||
| * | ||
| * @param promotionParameters the promotion parameters | ||
| * @param subtractPoints the points that shall be subtracted from the user's token | ||
| * @return a spendDeductTree for this statement | ||
| */ | ||
| public static SpendDeductTree generateSimpleTestSpendDeductZkp(PromotionParameters promotionParameters, | ||
| Vector<BigInteger> subtractPoints) { | ||
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| Vector<BigInteger> ignore = Util.getNullBigIntegerVector(promotionParameters.getPointsVectorSize()); | ||
| Vector<BigInteger> ones = Util.getOneBigIntegerVector(promotionParameters.getPointsVectorSize()); | ||
| Vector<BigInteger> negatedSubtractPoints = Vector.fromStreamPlain(subtractPoints.stream().map(BigInteger::negate)); | ||
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| return generateTestZkp( | ||
| subtractPoints, | ||
| ignore, | ||
| ignore, | ||
| ignore, | ||
| ones, | ||
| negatedSubtractPoints); | ||
| } | ||
|
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| /** | ||
| * Helper that generates a ZKP of the following form over the old and new point vectors: | ||
| * <p> | ||
| * Metadata correct | ||
| * {@literal ^ lowerLimits <= points <= upperLimits} | ||
| * {@literal ^ newLowerLimits <= newPoints <= newUpperLimits} | ||
| * {@literal ^ for all i: newPoints_i = a_i * oldPoints_i + b_i} | ||
| * | ||
| * @param lowerLimits vector of lower limits for the old points, null means not checked | ||
| * @param upperLimits vector of upper limits for the old points, null means not checked | ||
| * @param newLowerLimits vector of lower limits for the new points, null means not checked | ||
| * @param newUpperLimits vector of upper limits for the new points, null means not checked | ||
| * @param aVector vector of factors a_i for the linear relation proof. Ignore if null | ||
| * @param bVector vector of summands b_i for the linear relation proof. Ignore if null | ||
| * @return spendDeductTree for the upper statement | ||
| */ | ||
| public static SpendDeductTree generateTestZkp(Vector<BigInteger> lowerLimits, | ||
| Vector<BigInteger> upperLimits, | ||
| Vector<BigInteger> newLowerLimits, | ||
| Vector<BigInteger> newUpperLimits, | ||
| Vector<BigInteger> aVector, | ||
| Vector<BigInteger> bVector) { | ||
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| SpendDeductTree conditionTree = new TokenPointsLeaf("RangeProof", lowerLimits, upperLimits); | ||
| SpendDeductTree updateTree = new TokenUpdateLeaf("UpdateProof", newLowerLimits, newUpperLimits, aVector, bVector); | ||
| return new SpendDeductAndNode(updateTree, conditionTree); | ||
| } | ||
| } |
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