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briar/briar-tests/src/org/briarproject/crypto/EllipticCurveMultiplicationTest.java

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5.1 KiB
Java

package org.briarproject.crypto;
import org.briarproject.BriarTestCase;
import org.junit.Test;
import org.spongycastle.asn1.teletrust.TeleTrusTNamedCurves;
import org.spongycastle.asn1.x9.X9ECParameters;
import org.spongycastle.crypto.AsymmetricCipherKeyPair;
import org.spongycastle.crypto.agreement.ECDHCBasicAgreement;
import org.spongycastle.crypto.generators.ECKeyPairGenerator;
import org.spongycastle.crypto.params.ECDomainParameters;
import org.spongycastle.crypto.params.ECKeyGenerationParameters;
import org.spongycastle.crypto.params.ECPrivateKeyParameters;
import org.spongycastle.crypto.params.ECPublicKeyParameters;
import org.spongycastle.math.ec.ECCurve;
import org.spongycastle.math.ec.ECPoint;
import java.math.BigInteger;
import java.security.SecureRandom;
import static org.briarproject.crypto.EllipticCurveConstants.PARAMETERS;
import static org.junit.Assert.assertEquals;
public class EllipticCurveMultiplicationTest extends BriarTestCase {
@Test
public void testMultiplierProducesSameResultsAsDefault() throws Exception {
// Instantiate the default implementation of the curve
X9ECParameters defaultX9Parameters =
TeleTrusTNamedCurves.getByName("brainpoolp256r1");
ECCurve defaultCurve = defaultX9Parameters.getCurve();
ECPoint defaultG = defaultX9Parameters.getG();
BigInteger defaultN = defaultX9Parameters.getN();
BigInteger defaultH = defaultX9Parameters.getH();
// Check that the default parameters are equal to our parameters
assertEquals(PARAMETERS.getCurve(), defaultCurve);
assertEquals(PARAMETERS.getG(), defaultG);
assertEquals(PARAMETERS.getN(), defaultN);
assertEquals(PARAMETERS.getH(), defaultH);
// ECDomainParameters doesn't have an equals() method, but it's just a
// container for the parameters
ECDomainParameters defaultParameters = new ECDomainParameters(
defaultCurve, defaultG, defaultN, defaultH);
// Generate two key pairs with each set of parameters, using the same
// deterministic PRNG for both sets of parameters
byte[] seed = new byte[32];
new SecureRandom().nextBytes(seed);
// Montgomery ladder multiplier
SecureRandom random = new FortunaSecureRandom(seed);
ECKeyGenerationParameters montgomeryGeneratorParams =
new ECKeyGenerationParameters(PARAMETERS, random);
ECKeyPairGenerator montgomeryGenerator = new ECKeyPairGenerator();
montgomeryGenerator.init(montgomeryGeneratorParams);
AsymmetricCipherKeyPair montgomeryKeyPair1 =
montgomeryGenerator.generateKeyPair();
ECPrivateKeyParameters montgomeryPrivate1 =
(ECPrivateKeyParameters) montgomeryKeyPair1.getPrivate();
ECPublicKeyParameters montgomeryPublic1 =
(ECPublicKeyParameters) montgomeryKeyPair1.getPublic();
AsymmetricCipherKeyPair montgomeryKeyPair2 =
montgomeryGenerator.generateKeyPair();
ECPrivateKeyParameters montgomeryPrivate2 =
(ECPrivateKeyParameters) montgomeryKeyPair2.getPrivate();
ECPublicKeyParameters montgomeryPublic2 =
(ECPublicKeyParameters) montgomeryKeyPair2.getPublic();
// Default multiplier
random = new FortunaSecureRandom(seed);
ECKeyGenerationParameters defaultGeneratorParams =
new ECKeyGenerationParameters(defaultParameters, random);
ECKeyPairGenerator defaultGenerator = new ECKeyPairGenerator();
defaultGenerator.init(defaultGeneratorParams);
AsymmetricCipherKeyPair defaultKeyPair1 =
defaultGenerator.generateKeyPair();
ECPrivateKeyParameters defaultPrivate1 =
(ECPrivateKeyParameters) defaultKeyPair1.getPrivate();
ECPublicKeyParameters defaultPublic1 =
(ECPublicKeyParameters) defaultKeyPair1.getPublic();
AsymmetricCipherKeyPair defaultKeyPair2 =
defaultGenerator.generateKeyPair();
ECPrivateKeyParameters defaultPrivate2 =
(ECPrivateKeyParameters) defaultKeyPair2.getPrivate();
ECPublicKeyParameters defaultPublic2 =
(ECPublicKeyParameters) defaultKeyPair2.getPublic();
// The key pairs generated with both sets of parameters should be equal
assertEquals(montgomeryPrivate1.getD(), defaultPrivate1.getD());
assertEquals(montgomeryPublic1.getQ(), defaultPublic1.getQ());
assertEquals(montgomeryPrivate2.getD(), defaultPrivate2.getD());
assertEquals(montgomeryPublic2.getQ(), defaultPublic2.getQ());
// OK, all of the above was just sanity checks - now for the test!
ECDHCBasicAgreement agreement = new ECDHCBasicAgreement();
agreement.init(montgomeryPrivate1);
BigInteger sharedSecretMontgomeryMontgomery =
agreement.calculateAgreement(montgomeryPublic2);
agreement.init(montgomeryPrivate1);
BigInteger sharedSecretMontgomeryDefault =
agreement.calculateAgreement(defaultPublic2);
agreement.init(defaultPrivate1);
BigInteger sharedSecretDefaultMontgomery =
agreement.calculateAgreement(montgomeryPublic2);
agreement.init(defaultPrivate1);
BigInteger sharedSecretDefaultDefault =
agreement.calculateAgreement(defaultPublic2);
// Shared secrets calculated with different multipliers should be equal
assertEquals(sharedSecretMontgomeryMontgomery,
sharedSecretMontgomeryDefault);
assertEquals(sharedSecretMontgomeryMontgomery,
sharedSecretDefaultMontgomery);
assertEquals(sharedSecretMontgomeryMontgomery,
sharedSecretDefaultDefault);
}
}