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Code Issues Projects Releases Wiki Activity

Use Curve25519 for key agreement.

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This commit is contained in:
akwizgran
2018-02-02 17:52:18 +00:00
parent ad241a14e3
commit 56a5b8df87
11 changed files with 120 additions and 88 deletions
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54
bramble-core/src/main/java/org/briarproject/bramble/crypto/CryptoComponentImpl.java
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@@ -14,15 +14,11 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
import org.briarproject.bramble.api.system.SecureRandomProvider;
import org.briarproject.bramble.util.ByteUtils;
import org.briarproject.bramble.util.StringUtils;
import org.spongycastle.crypto.AsymmetricCipherKeyPair;
import org.spongycastle.crypto.CryptoException;
import org.spongycastle.crypto.Digest;
import org.spongycastle.crypto.agreement.ECDHCBasicAgreement;
import org.spongycastle.crypto.digests.Blake2bDigest;
import org.spongycastle.crypto.generators.ECKeyPairGenerator;
import org.spongycastle.crypto.params.ECKeyGenerationParameters;
import org.spongycastle.crypto.params.ECPrivateKeyParameters;
import org.spongycastle.crypto.params.ECPublicKeyParameters;
import org.whispersystems.curve25519.Curve25519;
import org.whispersystems.curve25519.Curve25519KeyPair;
import java.security.GeneralSecurityException;
import java.security.NoSuchAlgorithmException;
@@ -35,7 +31,6 @@ import javax.annotation.Nullable;
import javax.inject.Inject;
import static java.util.logging.Level.INFO;
import static org.briarproject.bramble.crypto.EllipticCurveConstants.PARAMETERS;
import static org.briarproject.bramble.util.ByteUtils.INT_32_BYTES;
@NotNullByDefault
@@ -44,7 +39,6 @@ class CryptoComponentImpl implements CryptoComponent {
private static final Logger LOG =
Logger.getLogger(CryptoComponentImpl.class.getName());
private static final int AGREEMENT_KEY_PAIR_BITS = 256;
private static final int SIGNATURE_KEY_PAIR_BITS = 256;
private static final int STORAGE_IV_BYTES = 24; // 196 bits
private static final int PBKDF_SALT_BYTES = 32; // 256 bits
@@ -52,7 +46,7 @@ class CryptoComponentImpl implements CryptoComponent {
private final SecureRandom secureRandom;
private final PasswordBasedKdf passwordBasedKdf;
private final ECKeyPairGenerator agreementKeyPairGenerator;
private final Curve25519 curve25519;
private final KeyPairGenerator signatureKeyPairGenerator;
private final KeyParser agreementKeyParser, signatureKeyParser;
private final MessageEncrypter messageEncrypter;
@@ -80,15 +74,11 @@ class CryptoComponentImpl implements CryptoComponent {
}
secureRandom = new SecureRandom();
this.passwordBasedKdf = passwordBasedKdf;
ECKeyGenerationParameters params = new ECKeyGenerationParameters(
PARAMETERS, secureRandom);
agreementKeyPairGenerator = new ECKeyPairGenerator();
agreementKeyPairGenerator.init(params);
curve25519 = Curve25519.getInstance("java");
signatureKeyPairGenerator = new KeyPairGenerator();
signatureKeyPairGenerator.initialize(SIGNATURE_KEY_PAIR_BITS,
secureRandom);
agreementKeyParser = new Sec1KeyParser(PARAMETERS,
AGREEMENT_KEY_PAIR_BITS);
agreementKeyParser = new Curve25519KeyParser();
signatureKeyParser = new EdKeyParser();
messageEncrypter = new MessageEncrypter(secureRandom);
}
@@ -133,16 +123,17 @@ class CryptoComponentImpl implements CryptoComponent {
// Package access for testing
byte[] performRawKeyAgreement(PrivateKey priv, PublicKey pub)
throws GeneralSecurityException {
if (!(priv instanceof Sec1PrivateKey))
if (!(priv instanceof Curve25519PrivateKey))
throw new IllegalArgumentException();
if (!(pub instanceof Sec1PublicKey))
if (!(pub instanceof Curve25519PublicKey))
throw new IllegalArgumentException();
ECPrivateKeyParameters ecPriv = ((Sec1PrivateKey) priv).getKey();
ECPublicKeyParameters ecPub = ((Sec1PublicKey) pub).getKey();
long now = System.currentTimeMillis();
ECDHCBasicAgreement agreement = new ECDHCBasicAgreement();
agreement.init(ecPriv);
byte[] secret = agreement.calculateAgreement(ecPub).toByteArray();
byte[] secret = curve25519.calculateAgreement(pub.getEncoded(),
priv.getEncoded());
// If the shared secret is all zeroes, the public key is invalid
byte allZero = 0;
for (byte b : secret) allZero |= b;
if (allZero == 0) throw new GeneralSecurityException();
long duration = System.currentTimeMillis() - now;
if (LOG.isLoggable(INFO))
LOG.info("Deriving shared secret took " + duration + " ms");
@@ -151,18 +142,10 @@ class CryptoComponentImpl implements CryptoComponent {
@Override
public KeyPair generateAgreementKeyPair() {
AsymmetricCipherKeyPair keyPair =
agreementKeyPairGenerator.generateKeyPair();
// Return a wrapper that uses the SEC 1 encoding
ECPublicKeyParameters ecPublicKey =
(ECPublicKeyParameters) keyPair.getPublic();
PublicKey publicKey = new Sec1PublicKey(ecPublicKey
);
ECPrivateKeyParameters ecPrivateKey =
(ECPrivateKeyParameters) keyPair.getPrivate();
PrivateKey privateKey = new Sec1PrivateKey(ecPrivateKey,
AGREEMENT_KEY_PAIR_BITS);
return new KeyPair(publicKey, privateKey);
Curve25519KeyPair keyPair = curve25519.generateKeyPair();
PublicKey pub = new Curve25519PublicKey(keyPair.getPublicKey());
PrivateKey priv = new Curve25519PrivateKey(keyPair.getPrivateKey());
return new KeyPair(pub, priv);
}
@Override
@@ -172,7 +155,8 @@ class CryptoComponentImpl implements CryptoComponent {
@Override
public KeyPair generateSignatureKeyPair() {
java.security.KeyPair keyPair = signatureKeyPairGenerator.generateKeyPair();
java.security.KeyPair keyPair =
signatureKeyPairGenerator.generateKeyPair();
EdDSAPublicKey edPublicKey = (EdDSAPublicKey) keyPair.getPublic();
PublicKey publicKey = new EdPublicKey(edPublicKey.getAbyte());
EdDSAPrivateKey edPrivateKey = (EdDSAPrivateKey) keyPair.getPrivate();

26
bramble-core/src/main/java/org/briarproject/bramble/crypto/Curve25519KeyParser.java Normal file
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@@ -0,0 +1,26 @@
package org.briarproject.bramble.crypto;
import org.briarproject.bramble.api.crypto.KeyParser;
import org.briarproject.bramble.api.crypto.PrivateKey;
import org.briarproject.bramble.api.crypto.PublicKey;
import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
import java.security.GeneralSecurityException;
@NotNullByDefault
class Curve25519KeyParser implements KeyParser {
@Override
public PublicKey parsePublicKey(byte[] encodedKey)
throws GeneralSecurityException {
if (encodedKey.length != 32) throw new GeneralSecurityException();
return new Curve25519PublicKey(encodedKey);
}
@Override
public PrivateKey parsePrivateKey(byte[] encodedKey)
throws GeneralSecurityException {
if (encodedKey.length != 32) throw new GeneralSecurityException();
return new Curve25519PrivateKey(encodedKey);
}
}

18
bramble-core/src/main/java/org/briarproject/bramble/crypto/Curve25519PrivateKey.java Normal file
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@@ -0,0 +1,18 @@
package org.briarproject.bramble.crypto;
import org.briarproject.bramble.api.Bytes;
import org.briarproject.bramble.api.crypto.PrivateKey;
import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
@NotNullByDefault
class Curve25519PrivateKey extends Bytes implements PrivateKey {
Curve25519PrivateKey(byte[] bytes) {
super(bytes);
}
@Override
public byte[] getEncoded() {
return getBytes();
}
}

18
bramble-core/src/main/java/org/briarproject/bramble/crypto/Curve25519PublicKey.java Normal file
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@@ -0,0 +1,18 @@
package org.briarproject.bramble.crypto;
import org.briarproject.bramble.api.Bytes;
import org.briarproject.bramble.api.crypto.PublicKey;
import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
@NotNullByDefault
class Curve25519PublicKey extends Bytes implements PublicKey {
Curve25519PublicKey(byte[] bytes) {
super(bytes);
}
@Override
public byte[] getEncoded() {
return getBytes();
}
}

32
bramble-core/src/main/java/org/briarproject/bramble/crypto/EllipticCurveConstants.java
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@@ -1,32 +0,0 @@
package org.briarproject.bramble.crypto;
import org.spongycastle.asn1.teletrust.TeleTrusTNamedCurves;
import org.spongycastle.asn1.x9.X9ECParameters;
import org.spongycastle.crypto.params.ECDomainParameters;
import org.spongycastle.math.ec.ECCurve;
import org.spongycastle.math.ec.ECMultiplier;
import org.spongycastle.math.ec.ECPoint;
import org.spongycastle.math.ec.MontgomeryLadderMultiplier;
import java.math.BigInteger;
/**
* Parameters for curve brainpoolp256r1 - see RFC 5639.
*/
class EllipticCurveConstants {
static final ECDomainParameters PARAMETERS;
static {
// Start with the default implementation of the curve
X9ECParameters x9 = TeleTrusTNamedCurves.getByName("brainpoolp256r1");
// Use a constant-time multiplier
ECMultiplier monty = new MontgomeryLadderMultiplier();
ECCurve curve = x9.getCurve().configure().setMultiplier(monty).create();
BigInteger gX = x9.getG().getAffineXCoord().toBigInteger();
BigInteger gY = x9.getG().getAffineYCoord().toBigInteger();
ECPoint g = curve.createPoint(gX, gY);
// Convert to ECDomainParameters using the new multiplier
PARAMETERS = new ECDomainParameters(curve, g, x9.getN(), x9.getH());
}
}