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/*
* Copyright (C) 2021, Thomas Wolf <thomas.wolf@paranor.ch> and others
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0 which is available at
* https://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package org.eclipse.jgit.gpg.bc.internal;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.text.MessageFormat;
import java.time.Instant;
import java.util.Date;
import java.util.List;
import java.util.Locale;
import org.bouncycastle.bcpg.sig.IssuerFingerprint;
import org.bouncycastle.openpgp.PGPCompressedData;
import org.bouncycastle.openpgp.PGPException;
import org.bouncycastle.openpgp.PGPPublicKey;
import org.bouncycastle.openpgp.PGPSignature;
import org.bouncycastle.openpgp.PGPSignatureList;
import org.bouncycastle.openpgp.PGPSignatureSubpacketVector;
import org.bouncycastle.openpgp.PGPUtil;
import org.bouncycastle.openpgp.jcajce.JcaPGPObjectFactory;
import org.bouncycastle.openpgp.operator.jcajce.JcaPGPContentVerifierBuilderProvider;
import org.bouncycastle.util.encoders.Hex;
import org.eclipse.jgit.api.errors.JGitInternalException;
import org.eclipse.jgit.lib.GpgConfig;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.lib.SignatureVerifier;
import org.eclipse.jgit.util.LRUMap;
import org.eclipse.jgit.util.StringUtils;
/**
* A {@link SignatureVerifier} to verify GPG signatures using BouncyCastle.
*/
public class BouncyCastleGpgSignatureVerifier
implements SignatureVerifier {
private static final String NAME = "bc"; //$NON-NLS-1$
// To support more efficient signature verification of multiple objects we
// cache public keys once found in a LRU cache.
private static final Object NO_KEY = new Object();
private LRUMap<String, Object> byFingerprint = new LRUMap<>(16, 200);
private LRUMap<String, Object> bySigner = new LRUMap<>(16, 200);
@Override
public String getName() {
return NAME;
}
static PGPSignature parseSignature(InputStream in)
throws IOException, PGPException {
try (InputStream sigIn = PGPUtil.getDecoderStream(in)) {
JcaPGPObjectFactory pgpFactory = new JcaPGPObjectFactory(sigIn);
Object obj = pgpFactory.nextObject();
if (obj instanceof PGPCompressedData) {
obj = new JcaPGPObjectFactory(
((PGPCompressedData) obj).getDataStream()).nextObject();
}
if (obj instanceof PGPSignatureList) {
return ((PGPSignatureList) obj).get(0);
}
return null;
}
}
@Override
public SignatureVerification verify(Repository repository, GpgConfig config,
byte[] data, byte[] signatureData) throws IOException {
PGPSignature signature = null;
String fingerprint = null;
String signer = null;
String keyId = null;
try (InputStream sigIn = new ByteArrayInputStream(signatureData)) {
signature = parseSignature(sigIn);
if (signature != null) {
// Try to figure out something to find the public key with.
if (signature.hasSubpackets()) {
PGPSignatureSubpacketVector packets = signature
.getHashedSubPackets();
IssuerFingerprint fingerprintPacket = packets
.getIssuerFingerprint();
if (fingerprintPacket != null) {
fingerprint = Hex
.toHexString(fingerprintPacket.getFingerprint())
.toLowerCase(Locale.ROOT);
}
signer = packets.getSignerUserID();
if (signer != null) {
signer = BouncyCastleGpgSigner.extractSignerId(signer);
}
}
keyId = Long.toUnsignedString(signature.getKeyID(), 16)
.toLowerCase(Locale.ROOT);
} else {
throw new JGitInternalException(BCText.get().nonSignatureError);
}
} catch (NumberFormatException | PGPException e) {
throw new JGitInternalException(BCText.get().signatureParseError,
e);
}
Date signatureCreatedAt = signature.getCreationTime();
if (fingerprint == null && signer == null && keyId == null) {
return new SignatureVerification(NAME, signatureCreatedAt,
null, null, null, false, false, TrustLevel.UNKNOWN,
BCText.get().signatureNoKeyInfo);
}
if (fingerprint != null && keyId != null
&& !fingerprint.endsWith(keyId)) {
return new SignatureVerification(NAME, signatureCreatedAt,
signer, fingerprint, signer, false, false,
TrustLevel.UNKNOWN,
MessageFormat.format(BCText.get().signatureInconsistent,
keyId, fingerprint));
}
if (fingerprint == null && keyId != null) {
fingerprint = keyId;
}
// Try to find the public key
String keySpec = '<' + signer + '>';
Object cached = null;
BouncyCastleGpgPublicKey publicKey = null;
try {
cached = byFingerprint.get(fingerprint);
if (cached != null) {
if (cached instanceof BouncyCastleGpgPublicKey) {
publicKey = (BouncyCastleGpgPublicKey) cached;
}
} else if (!StringUtils.isEmptyOrNull(signer)) {
cached = bySigner.get(signer);
if (cached != null) {
if (cached instanceof BouncyCastleGpgPublicKey) {
publicKey = (BouncyCastleGpgPublicKey) cached;
}
}
}
if (cached == null) {
publicKey = BouncyCastleGpgKeyLocator.findPublicKey(fingerprint,
keySpec);
}
} catch (IOException | PGPException e) {
throw new JGitInternalException(
BCText.get().signatureKeyLookupError, e);
}
if (publicKey == null) {
if (cached == null) {
byFingerprint.put(fingerprint, NO_KEY);
byFingerprint.put(keyId, NO_KEY);
if (signer != null) {
bySigner.put(signer, NO_KEY);
}
}
return new SignatureVerification(NAME, signatureCreatedAt,
signer, fingerprint, signer, false, false,
TrustLevel.UNKNOWN, BCText.get().signatureNoPublicKey);
}
if (fingerprint != null && !publicKey.isExactMatch()) {
// We did find _some_ signing key for the signer, but it doesn't
// match the given fingerprint.
return new SignatureVerification(NAME, signatureCreatedAt,
signer, fingerprint, signer, false, false,
TrustLevel.UNKNOWN,
MessageFormat.format(BCText.get().signatureNoSigningKey,
fingerprint));
}
if (cached == null) {
byFingerprint.put(fingerprint, publicKey);
byFingerprint.put(keyId, publicKey);
if (signer != null) {
bySigner.put(signer, publicKey);
}
}
String user = null;
List<String> userIds = publicKey.getUserIds();
if (userIds != null && !userIds.isEmpty()) {
if (!StringUtils.isEmptyOrNull(signer)) {
for (String userId : publicKey.getUserIds()) {
if (BouncyCastleGpgKeyLocator.containsSigningKey(userId,
keySpec)) {
user = userId;
break;
}
}
}
if (user == null) {
user = userIds.get(0);
}
} else if (signer != null) {
user = signer;
}
PGPPublicKey pubKey = publicKey.getPublicKey();
boolean expired = false;
long validFor = pubKey.getValidSeconds();
if (validFor > 0 && signatureCreatedAt != null) {
Instant expiredAt = pubKey.getCreationTime().toInstant()
.plusSeconds(validFor);
expired = expiredAt.isBefore(signatureCreatedAt.toInstant());
}
// Trust data is not defined in OpenPGP; the format is implementation
// specific. We don't use the GPG trustdb but simply the trust packet
// on the public key, if present. Even if present, it may or may not
// be set.
byte[] trustData = pubKey.getTrustData();
TrustLevel trust = parseGpgTrustPacket(trustData);
boolean verified = false;
try {
signature.init(
new JcaPGPContentVerifierBuilderProvider(),
pubKey);
signature.update(data);
verified = signature.verify();
} catch (PGPException e) {
throw new JGitInternalException(
BCText.get().signatureVerificationError, e);
}
return new SignatureVerification(NAME, signatureCreatedAt, signer,
fingerprint, user, verified, expired, trust, null);
}
private TrustLevel parseGpgTrustPacket(byte[] packet) {
if (packet == null || packet.length < 6) {
// A GPG trust packet has at least 6 bytes.
return TrustLevel.UNKNOWN;
}
if (packet[2] != 'g' || packet[3] != 'p' || packet[4] != 'g') {
// Not a GPG trust packet
return TrustLevel.UNKNOWN;
}
int trust = packet[0] & 0x0F;
switch (trust) {
case 0: // No determined/set
case 1: // Trust expired; i.e., calculation outdated or key expired
case 2: // Undefined: not enough information to set
return TrustLevel.UNKNOWN;
case 3:
return TrustLevel.NEVER;
case 4:
return TrustLevel.MARGINAL;
case 5:
return TrustLevel.FULL;
case 6:
return TrustLevel.ULTIMATE;
default:
return TrustLevel.UNKNOWN;
}
}
@Override
public void clear() {
byFingerprint.clear();
bySigner.clear();
}
}
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