Fix CachingBcPublicKeyDataDecryptorFactory

pgpainless-core/src/main/java/org/bouncycastle/CachingBcPublicKeyDataDecryptorFactory.java

@@ -5,9 +5,15 @@
 package org.bouncycastle;
 
 import org.bouncycastle.openpgp.PGPException;
-import org.bouncycastle.openpgp.operator.PGPDataDecryptor;
+import org.bouncycastle.openpgp.PGPPrivateKey;
 import org.bouncycastle.openpgp.operator.PublicKeyDataDecryptorFactory;
+import org.bouncycastle.openpgp.operator.bc.BcPublicKeyDataDecryptorFactory;
 import org.bouncycastle.util.encoders.Base64;
+import org.bouncycastle.util.encoders.Hex;
+import org.pgpainless.decryption_verification.CustomPublicKeyDataDecryptorFactory;
+import org.pgpainless.key.SubkeyIdentifier;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.util.HashMap;
 import java.util.Map;
@@ -20,36 +26,46 @@ import java.util.Map;
  * cache hits.
  * If no hit is found, the method call is delegated to the underlying {@link PublicKeyDataDecryptorFactory}.
  * The result of that is then placed in the cache and returned.
- *
- * TODO: Do we also cache invalid session keys?
  */
-public class CachingPublicKeyDataDecryptorFactory implements PublicKeyDataDecryptorFactory {
+public class CachingBcPublicKeyDataDecryptorFactory
+        extends BcPublicKeyDataDecryptorFactory
+        implements CustomPublicKeyDataDecryptorFactory {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(CachingBcPublicKeyDataDecryptorFactory.class);
 
     private final Map<String, byte[]> cachedSessionKeys = new HashMap<>();
-    private final PublicKeyDataDecryptorFactory factory;
+    private final SubkeyIdentifier decryptionKey;
 
-    public CachingPublicKeyDataDecryptorFactory(PublicKeyDataDecryptorFactory factory) {
+    public CachingBcPublicKeyDataDecryptorFactory(PGPPrivateKey privateKey, SubkeyIdentifier decryptionKey) {
-        this.factory = factory;
+        super(privateKey);
+        this.decryptionKey = decryptionKey;
     }
 
     @Override
     public byte[] recoverSessionData(int keyAlgorithm, byte[][] secKeyData) throws PGPException {
-        byte[] sessionKey = lookup(secKeyData);
+        byte[] sessionKey = lookupSessionKeyData(secKeyData);
         if (sessionKey == null) {
-            sessionKey = factory.recoverSessionData(keyAlgorithm, secKeyData);
+            LOGGER.debug("Cache miss for encrypted session key " + Hex.toHexString(secKeyData[0]));
-            cache(secKeyData, sessionKey);
+            sessionKey = costlyRecoverSessionData(keyAlgorithm, secKeyData);
+            cacheSessionKeyData(secKeyData, sessionKey);
+        } else {
+            LOGGER.debug("Cache hit for encrypted session key " + Hex.toHexString(secKeyData[0]));
         }
         return sessionKey;
     }
 
-    private byte[] lookup(byte[][] secKeyData) {
+    public byte[] costlyRecoverSessionData(int keyAlgorithm, byte[][] secKeyData) throws PGPException {
+        return super.recoverSessionData(keyAlgorithm, secKeyData);
+    }
+
+    private byte[] lookupSessionKeyData(byte[][] secKeyData) {
         byte[] sk = secKeyData[0];
         String key = Base64.toBase64String(sk);
         byte[] sessionKey = cachedSessionKeys.get(key);
         return copy(sessionKey);
     }
 
-    private void cache(byte[][] secKeyData, byte[] sessionKey) {
+    private void cacheSessionKeyData(byte[][] secKeyData, byte[] sessionKey) {
         byte[] sk = secKeyData[0];
         String key = Base64.toBase64String(sk);
         cachedSessionKeys.put(key, copy(sessionKey));
@@ -69,7 +85,7 @@ public class CachingPublicKeyDataDecryptorFactory implements PublicKeyDataDecryp
     }
 
     @Override
-    public PGPDataDecryptor createDataDecryptor(boolean withIntegrityPacket, int encAlgorithm, byte[] key) throws PGPException {
+    public SubkeyIdentifier getSubkeyIdentifier() {
-        return null;
+        return decryptionKey;
     }
 }

pgpainless-core/src/test/java/bouncycastle/CachingBcPublicKeyDataDecryptorFactoryTest.java

@@ -0,0 +1,96 @@
+// SPDX-FileCopyrightText: 2022 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package bouncycastle;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.security.InvalidAlgorithmParameterException;
+import java.security.NoSuchAlgorithmException;
+
+import org.bouncycastle.CachingBcPublicKeyDataDecryptorFactory;
+import org.bouncycastle.openpgp.PGPException;
+import org.bouncycastle.openpgp.PGPPrivateKey;
+import org.bouncycastle.openpgp.PGPSecretKey;
+import org.bouncycastle.openpgp.PGPSecretKeyRing;
+import org.bouncycastle.util.io.Streams;
+import org.junit.jupiter.api.Test;
+import org.pgpainless.PGPainless;
+import org.pgpainless.algorithm.EncryptionPurpose;
+import org.pgpainless.decryption_verification.ConsumerOptions;
+import org.pgpainless.decryption_verification.DecryptionStream;
+import org.pgpainless.key.SubkeyIdentifier;
+import org.pgpainless.key.info.KeyRingInfo;
+import org.pgpainless.key.protection.SecretKeyRingProtector;
+import org.pgpainless.key.protection.UnlockSecretKey;
+
+public class CachingBcPublicKeyDataDecryptorFactoryTest {
+
+    private static final String KEY = "-----BEGIN PGP PRIVATE KEY BLOCK-----\n" +
+            "Version: PGPainless\n" +
+            "Comment: C8AE 4279 5958 5F46 86A9  8B5F EC69 7C29 2BE4 44E0\n" +
+            "Comment: Alice\n" +
+            "\n" +
+            "lFgEY1vEcxYJKwYBBAHaRw8BAQdAXOUK1uc1iBeM+mMt2nLCukXWoJd/SodrtN9S\n" +
+            "U/zzwu0AAP9eePPw91KLuq6PF9jQoTRz/cW4CyiALNJpsOJIZ1rp3xOBtAVBbGlj\n" +
+            "ZYiPBBMWCgBBBQJjW8RzCRDsaXwpK+RE4BYhBMiuQnlZWF9GhqmLX+xpfCkr5ETg\n" +
+            "Ap4BApsBBRYCAwEABAsJCAcFFQoJCAsCmQEAAGqWAQC8oz7l8izjUis5ji+sgI+q\n" +
+            "gML22VNybqmLBpzZwnNU5wEApe9fNTRbK5yAITGBscxH7o74Qe+CLI6Ni5MwzKxr\n" +
+            "5AucXQRjW8RzEgorBgEEAZdVAQUBAQdAm8xk0QSvpp2ZU1KQ31E7eEZYLKpbW4JE\n" +
+            "opmtMQx6AlIDAQgHAAD/XTb/qSosfkNvli3BQiUzVRAqKaU4PKAq7at6afxoYSgN\n" +
+            "4Yh1BBgWCgAdBQJjW8RzAp4BApsMBRYCAwEABAsJCAcFFQoJCAsACgkQ7Gl8KSvk\n" +
+            "ROB38QEA0MvDt0bjEXwFoM0E34z0MtPcG3VBYcQ+iFRIqFfEl5UA/2yZxFjoZqrs\n" +
+            "AQE8TaVpXYfbc2p/GEKA9LGd9l/g0QQLnFgEY1vEcxYJKwYBBAHaRw8BAQdAyCOv\n" +
+            "6hGUvHcCBSDKP3fRz+scyJ9zwMt7nFXK5A/k2YgAAQCn3Es+IhvePn3eBlcYMMr0\n" +
+            "xcktrY1NJAIZPfjlUJ0J1g6LiNUEGBYKAH0FAmNbxHMCngECmwIFFgIDAQAECwkI\n" +
+            "BwUVCgkIC18gBBkWCgAGBQJjW8RzAAoJECxLf7KoUc8wD18BANNpIr4E+RRVVztR\n" +
+            "OVwdxSe0SRWGjkW8nHrRyghHKTuMAP9p4ZKicOYA1uZbiNNjyuJuS8xBH6Hihurb\n" +
+            "gDypVgxdBQAKCRDsaXwpK+RE4EQjAP9ARZEPxKNLFkrvjoZ8nrts3qhv3VtMrU+9\n" +
+            "huZnYLe1FQEAtgO6V7wutHvVARHXqPJ6lcv+SueIu+BjLFYEKuBwggs=\n" +
+            "=ShJd\n" +
+            "-----END PGP PRIVATE KEY BLOCK-----";
+
+    private static final String MSG = "-----BEGIN PGP MESSAGE-----\n" +
+            "Version: PGPainless\n" +
+            "\n" +
+            "hF4DJmQMTBqw3G8SAQdALkHpO0UkS/CqkwxUz74MJU3PV72ZrIL8ZcrO8ofhblkw\n" +
+            "iDIhSwwGTG3tj+sG+ZVWKsmONKi7Om5seJDHQtQ8MfdCELAgwYHSt6MrgDBhuDIH\n" +
+            "0kABZhq2/8qk3EGXPpc+xxs4r4g8SgHOiiHSim5NGtounXXIaF6T/hUmlorkeYf/\n" +
+            "a9pCC0QXRUAr8NOcdsfbvb5V\n" +
+            "=dQa8\n" +
+            "-----END PGP MESSAGE-----";
+
+    @Test
+    public void test() throws PGPException, InvalidAlgorithmParameterException, NoSuchAlgorithmException, IOException {
+        PGPSecretKeyRing secretKeys = PGPainless.readKeyRing().secretKeyRing(KEY);
+        SecretKeyRingProtector protector = SecretKeyRingProtector.unprotectedKeys();
+        KeyRingInfo info = PGPainless.inspectKeyRing(secretKeys);
+        SubkeyIdentifier decryptionKey = new SubkeyIdentifier(secretKeys,
+                info.getEncryptionSubkeys(EncryptionPurpose.ANY).get(0).getKeyID());
+
+        PGPSecretKey secretKey = secretKeys.getSecretKey(decryptionKey.getSubkeyId());
+        PGPPrivateKey privateKey = UnlockSecretKey.unlockSecretKey(secretKey, protector);
+        CachingBcPublicKeyDataDecryptorFactory cachingFactory = new CachingBcPublicKeyDataDecryptorFactory(
+                privateKey, decryptionKey);
+
+        ByteArrayInputStream ciphertextIn = new ByteArrayInputStream(MSG.getBytes());
+        DecryptionStream decryptionStream = PGPainless.decryptAndOrVerify()
+                .onInputStream(ciphertextIn)
+                .withOptions(ConsumerOptions.get()
+                        .addCustomDecryptorFactory(cachingFactory));
+
+        ByteArrayOutputStream out = new ByteArrayOutputStream();
+        Streams.pipeAll(decryptionStream, out);
+        decryptionStream.close();
+
+        decryptionStream = PGPainless.decryptAndOrVerify()
+                .onInputStream(ciphertextIn)
+                .withOptions(ConsumerOptions.get()
+                        .addCustomDecryptorFactory(cachingFactory));
+        out = new ByteArrayOutputStream();
+        Streams.pipeAll(decryptionStream, out);
+        decryptionStream.close();
+    }
+}