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Code Issues Releases Wiki Activity

WiP implementation of public key parameter validation

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This commit is contained in:
Paul Schaub 2021-11-24 18:46:29 +01:00
parent 3b49840c9c
commit 5364e21b5e
Signed by: vanitasvitae
GPG key ID: 62BEE9264BF17311
4 changed files with 199 additions and 3 deletions
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12
pgpainless-core/src/main/java/org/pgpainless/exception/KeyIntegrityException.java Normal file
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@ -0,0 +1,12 @@
// SPDX-FileCopyrightText: 2021 Paul Schaub <vanitasvitae@fsfe.org>
//
// SPDX-License-Identifier: Apache-2.0
package org.pgpainless.exception;
public class KeyIntegrityException extends AssertionError {
public KeyIntegrityException() {
super("Key Integrity Exception");
}
}

15
pgpainless-core/src/main/java/org/pgpainless/key/protection/UnlockSecretKey.java
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@ -9,8 +9,10 @@ import org.bouncycastle.openpgp.PGPException;
import org.bouncycastle.openpgp.PGPPrivateKey;
import org.bouncycastle.openpgp.PGPSecretKey;
import org.bouncycastle.openpgp.operator.PBESecretKeyDecryptor;
import org.pgpainless.exception.KeyIntegrityException;
import org.pgpainless.exception.WrongPassphraseException;
import org.pgpainless.key.info.KeyInfo;
import org.pgpainless.key.util.PublicKeyParameterValidationUtil;
import org.pgpainless.util.Passphrase;
public final class UnlockSecretKey {
@ -20,13 +22,20 @@ public final class UnlockSecretKey {
}
public static PGPPrivateKey unlockSecretKey(PGPSecretKey secretKey, SecretKeyRingProtector protector)
throws WrongPassphraseException {
throws WrongPassphraseException, KeyIntegrityException {
try {
PBESecretKeyDecryptor decryptor = null;
if (KeyInfo.isEncrypted(secretKey)) {
decryptor = protector.getDecryptor(secretKey.getKeyID());
}
return secretKey.extractPrivateKey(decryptor);
PGPPrivateKey privateKey = secretKey.extractPrivateKey(decryptor);
if (secretKey.getPublicKey() != null) {
PublicKeyParameterValidationUtil.verifyPublicKeyParameterIntegrity(privateKey, secretKey.getPublicKey());
}
return privateKey;
} catch (KeyIntegrityException e) {
throw e;
} catch (PGPException e) {
throw new WrongPassphraseException(secretKey.getKeyID(), e);
}
@ -40,7 +49,7 @@ public final class UnlockSecretKey {
}
}
public static PGPPrivateKey unlockSecretKey(PGPSecretKey secretKey, Passphrase passphrase) throws WrongPassphraseException {
public static PGPPrivateKey unlockSecretKey(PGPSecretKey secretKey, Passphrase passphrase) throws WrongPassphraseException, KeyIntegrityException {
return unlockSecretKey(secretKey, SecretKeyRingProtector.unlockSingleKeyWith(passphrase, secretKey));
}
}

172
pgpainless-core/src/main/java/org/pgpainless/key/util/PublicKeyParameterValidationUtil.java Normal file
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@ -0,0 +1,172 @@
// SPDX-FileCopyrightText: 2021 Paul Schaub <vanitasvitae@fsfe.org>
//
// SPDX-License-Identifier: Apache-2.0
package org.pgpainless.key.util;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.math.BigInteger;
import java.security.SecureRandom;
import org.bouncycastle.bcpg.BCPGKey;
import org.bouncycastle.bcpg.DSAPublicBCPGKey;
import org.bouncycastle.bcpg.DSASecretBCPGKey;
import org.bouncycastle.bcpg.EdDSAPublicBCPGKey;
import org.bouncycastle.bcpg.EdSecretBCPGKey;
import org.bouncycastle.bcpg.RSAPublicBCPGKey;
import org.bouncycastle.bcpg.RSASecretBCPGKey;
import org.bouncycastle.openpgp.PGPEncryptedDataGenerator;
import org.bouncycastle.openpgp.PGPEncryptedDataList;
import org.bouncycastle.openpgp.PGPException;
import org.bouncycastle.openpgp.PGPPrivateKey;
import org.bouncycastle.openpgp.PGPPublicKey;
import org.bouncycastle.openpgp.PGPPublicKeyEncryptedData;
import org.bouncycastle.openpgp.PGPSignature;
import org.bouncycastle.openpgp.PGPSignatureGenerator;
import org.bouncycastle.openpgp.operator.PublicKeyDataDecryptorFactory;
import org.bouncycastle.util.Arrays;
import org.bouncycastle.util.io.Streams;
import org.pgpainless.algorithm.HashAlgorithm;
import org.pgpainless.algorithm.PublicKeyAlgorithm;
import org.pgpainless.algorithm.SignatureType;
import org.pgpainless.algorithm.SymmetricKeyAlgorithm;
import org.pgpainless.exception.KeyIntegrityException;
import org.pgpainless.implementation.ImplementationFactory;
public class PublicKeyParameterValidationUtil {
public static void verifyPublicKeyParameterIntegrity(PGPPrivateKey privateKey, PGPPublicKey publicKey)
throws KeyIntegrityException, PGPException {
PublicKeyAlgorithm publicKeyAlgorithm = PublicKeyAlgorithm.fromId(publicKey.getAlgorithm());
boolean valid = true;
// Additional to the algorithm-specific tests further below, we also perform
// generic functionality tests with the key, such as whether it is able to decrypt encrypted data
// or verify signatures.
// These tests should be more or less constant time.
if (publicKeyAlgorithm.isSigningCapable()) {
valid = verifyCanSign(privateKey, publicKey) && valid;
}
if (publicKeyAlgorithm.isEncryptionCapable()) {
valid = verifyCanDecrypt(privateKey, publicKey) && valid;
}
// Algorithm specific validations
BCPGKey key = privateKey.getPrivateKeyDataPacket();
if (key instanceof RSASecretBCPGKey) {
valid = verifyRSAKeyIntegrity(
(RSASecretBCPGKey) key,
(RSAPublicBCPGKey) publicKey.getPublicKeyPacket().getKey())
&& valid;
} else if (key instanceof EdSecretBCPGKey) {
valid = verifyEdDsaKeyIntegrity(
(EdSecretBCPGKey) key,
(EdDSAPublicBCPGKey) publicKey.getPublicKeyPacket().getKey())
&& valid;
} else if (key instanceof DSASecretBCPGKey) {
valid = verifyDsaKeyIntegrity(
(DSASecretBCPGKey) key,
(DSAPublicBCPGKey) publicKey.getPublicKeyPacket().getKey())
&& valid;
}
// TODO: ElGamal
if (!valid) {
throw new KeyIntegrityException();
}
}
private static boolean verifyCanSign(PGPPrivateKey privateKey, PGPPublicKey publicKey) throws PGPException {
SecureRandom random = new SecureRandom();
PublicKeyAlgorithm publicKeyAlgorithm = PublicKeyAlgorithm.fromId(publicKey.getAlgorithm());
PGPSignatureGenerator signatureGenerator = new PGPSignatureGenerator(
ImplementationFactory.getInstance().getPGPContentSignerBuilder(publicKeyAlgorithm, HashAlgorithm.SHA256)
);
signatureGenerator.init(SignatureType.TIMESTAMP.getCode(), privateKey);
byte[] data = new byte[512];
random.nextBytes(data);
signatureGenerator.update(data);
PGPSignature sig = signatureGenerator.generate();
sig.init(ImplementationFactory.getInstance().getPGPContentVerifierBuilderProvider(), publicKey);
sig.update(data);
return sig.verify();
}
private static boolean verifyCanDecrypt(PGPPrivateKey privateKey, PGPPublicKey publicKey) {
SecureRandom random = new SecureRandom();
PGPEncryptedDataGenerator encryptedDataGenerator = new PGPEncryptedDataGenerator(
ImplementationFactory.getInstance().getPGPDataEncryptorBuilder(SymmetricKeyAlgorithm.AES_256)
);
encryptedDataGenerator.addMethod(
ImplementationFactory.getInstance().getPublicKeyKeyEncryptionMethodGenerator(publicKey));
byte[] data = new byte[1024];
random.nextBytes(data);
ByteArrayOutputStream out = new ByteArrayOutputStream();
try {
OutputStream outputStream = encryptedDataGenerator.open(out, new byte[1024]);
outputStream.write(data);
encryptedDataGenerator.close();
PGPEncryptedDataList encryptedDataList = new PGPEncryptedDataList(out.toByteArray());
PublicKeyDataDecryptorFactory decryptorFactory =
ImplementationFactory.getInstance().getPublicKeyDataDecryptorFactory(privateKey);
PGPPublicKeyEncryptedData encryptedData =
(PGPPublicKeyEncryptedData) encryptedDataList.getEncryptedDataObjects().next();
InputStream decrypted = encryptedData.getDataStream(decryptorFactory);
out = new ByteArrayOutputStream();
Streams.pipeAll(decrypted, out);
decrypted.close();
} catch (IOException | PGPException e) {
return false;
}
return Arrays.constantTimeAreEqual(data, out.toByteArray());
}
private static boolean verifyEdDsaKeyIntegrity(EdSecretBCPGKey privateKey, EdDSAPublicBCPGKey publicKey)
throws KeyIntegrityException {
// TODO: Implement
return true;
}
private static boolean verifyDsaKeyIntegrity(DSASecretBCPGKey privateKey, DSAPublicBCPGKey publicKey)
throws KeyIntegrityException {
// Not sure what value to put here in order to have a "robust" primality check
// I went with 40, since that's what SO recommends:
// https://stackoverflow.com/a/6330138
final int certainty = 40;
BigInteger pG = publicKey.getG();
BigInteger pP = publicKey.getP();
BigInteger pQ = publicKey.getQ();
BigInteger pY = publicKey.getY();
BigInteger sX = privateKey.getX();
boolean pPrime = pP.isProbablePrime(certainty);
boolean qPrime = pQ.isProbablePrime(certainty);
// q > 160 bits
boolean qLarge = pQ.getLowestSetBit() > 160;
// q divides p - 1
boolean qDividesPminus1 = pP.subtract(BigInteger.ONE).mod(pQ).equals(BigInteger.ZERO);
// 1 < g < p
boolean gInBounds = BigInteger.ONE.max(pG).equals(pG) && pG.max(pP).equals(pP);
// g^q = 1 mod p
boolean gPowXModPEquals1 = pG.modPow(pQ, pP).equals(BigInteger.ONE);
// y = g^x mod p
boolean yEqualsGPowXModP = pY.equals(pG.modPow(sX, pP));
return pPrime && qPrime && qLarge && qDividesPminus1 && gInBounds && gPowXModPEquals1 && yEqualsGPowXModP;
}
private static boolean verifyRSAKeyIntegrity(RSASecretBCPGKey secretKey, RSAPublicBCPGKey publicKey)
throws KeyIntegrityException {
// Verify that the public keys N is equal to private keys p*q
return publicKey.getModulus().equals(secretKey.getPrimeP().multiply(secretKey.getPrimeQ()));
}
}

3
pgpainless-core/src/test/java/org/pgpainless/key/generation/GenerateEllipticCurveKeyTest.java
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@ -21,6 +21,8 @@ import org.pgpainless.implementation.ImplementationFactory;
import org.pgpainless.key.generation.type.KeyType;
import org.pgpainless.key.generation.type.eddsa.EdDSACurve;
import org.pgpainless.key.generation.type.xdh.XDHSpec;
import org.pgpainless.key.protection.SecretKeyRingProtector;
import org.pgpainless.key.protection.UnlockSecretKey;
import org.pgpainless.key.util.UserId;
public class GenerateEllipticCurveKeyTest {
@ -38,5 +40,6 @@ public class GenerateEllipticCurveKeyTest {
.build();
assertEquals(PublicKeyAlgorithm.EDDSA.getAlgorithmId(), keyRing.getPublicKey().getAlgorithm());
UnlockSecretKey.unlockSecretKey(keyRing.getSecretKey(), SecretKeyRingProtector.unprotectedKeys());
}
}