Check MDC when stream is closed

pgpainless-core/src/main/java/org/pgpainless/decryption_verification/DecryptionStream.java

@@ -18,10 +18,12 @@ package org.pgpainless.decryption_verification;
 import javax.annotation.Nonnull;
 import java.io.IOException;
 import java.io.InputStream;
+import java.util.List;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
 import org.bouncycastle.openpgp.PGPException;
+import org.pgpainless.util.IntegrityProtectedInputStream;
 
 public class DecryptionStream extends InputStream {
 
@@ -30,10 +32,13 @@ public class DecryptionStream extends InputStream {
     private final InputStream inputStream;
     private final OpenPgpMetadata.Builder resultBuilder;
     private boolean isClosed = false;
+    private List<IntegrityProtectedInputStream> integrityProtectedInputStreamList;
 
-    DecryptionStream(@Nonnull InputStream wrapped, @Nonnull OpenPgpMetadata.Builder resultBuilder) {
+    DecryptionStream(@Nonnull InputStream wrapped, @Nonnull OpenPgpMetadata.Builder resultBuilder,
+                     List<IntegrityProtectedInputStream> integrityProtectedInputStreamList) {
         this.inputStream = wrapped;
         this.resultBuilder = resultBuilder;
+        this.integrityProtectedInputStreamList = integrityProtectedInputStreamList;
     }
 
     @Override
@@ -55,6 +60,9 @@ public class DecryptionStream extends InputStream {
     public void close() throws IOException {
         inputStream.close();
         maybeVerifyDetachedSignatures();
+        for (IntegrityProtectedInputStream s : integrityProtectedInputStreamList) {
+            s.close();
+        }
         this.isClosed = true;
     }
 

pgpainless-core/src/main/java/org/pgpainless/decryption_verification/DecryptionStreamFactory.java

@@ -17,6 +17,7 @@ package org.pgpainless.decryption_verification;
 
 import java.io.IOException;
 import java.io.InputStream;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
@@ -56,6 +57,7 @@ import org.pgpainless.algorithm.SymmetricKeyAlgorithm;
 import org.pgpainless.implementation.ImplementationFactory;
 import org.pgpainless.key.OpenPgpV4Fingerprint;
 import org.pgpainless.key.protection.SecretKeyRingProtector;
+import org.pgpainless.util.IntegrityProtectedInputStream;
 import org.pgpainless.util.Passphrase;
 
 public final class DecryptionStreamFactory {
@@ -73,6 +75,7 @@ public final class DecryptionStreamFactory {
     private static final PGPContentVerifierBuilderProvider verifierBuilderProvider = ImplementationFactory.getInstance().getPGPContentVerifierBuilderProvider();
     private static final KeyFingerPrintCalculator keyFingerprintCalculator = ImplementationFactory.getInstance().getKeyFingerprintCalculator();
     private final Map<OpenPgpV4Fingerprint, OnePassSignature> verifiableOnePassSignatures = new HashMap<>();
+    private final List<IntegrityProtectedInputStream> integrityProtectedStreams = new ArrayList<>();
 
     private DecryptionStreamFactory(@Nullable PGPSecretKeyRingCollection decryptionKeys,
                                     @Nullable SecretKeyRingProtector decryptor,
@@ -114,7 +117,7 @@ public final class DecryptionStreamFactory {
                     PGPUtil.getDecoderStream(inputStream), keyFingerprintCalculator);
             pgpInputStream = factory.processPGPPackets(objectFactory);
         }
-        return new DecryptionStream(pgpInputStream, factory.resultBuilder);
+        return new DecryptionStream(pgpInputStream, factory.resultBuilder, factory.integrityProtectedStreams);
     }
 
     private InputStream processPGPPackets(@Nonnull PGPObjectFactory objectFactory) throws IOException, PGPException {
@@ -253,11 +256,11 @@ public final class DecryptionStreamFactory {
             throw new PGPException("Decryption failed - No suitable decryption key or passphrase found");
         }
 
-        PublicKeyDataDecryptorFactory keyDecryptor = ImplementationFactory.getInstance()
+        PublicKeyDataDecryptorFactory dataDecryptor = ImplementationFactory.getInstance()
                 .getPublicKeyDataDecryptorFactory(decryptionKey);
 
         SymmetricKeyAlgorithm symmetricKeyAlgorithm = SymmetricKeyAlgorithm
-                .fromId(encryptedSessionKey.getSymmetricAlgorithm(keyDecryptor));
+                .fromId(encryptedSessionKey.getSymmetricAlgorithm(dataDecryptor));
         if (symmetricKeyAlgorithm == SymmetricKeyAlgorithm.NULL) {
             throw new PGPException("Data is not encrypted.");
         }
@@ -267,7 +270,13 @@ public final class DecryptionStreamFactory {
 
         resultBuilder.setIntegrityProtected(encryptedSessionKey.isIntegrityProtected());
 
-        return encryptedSessionKey.getDataStream(keyDecryptor);
+        if (encryptedSessionKey.isIntegrityProtected()) {
+            IntegrityProtectedInputStream integrityProtected =
+                    new IntegrityProtectedInputStream(encryptedSessionKey.getDataStream(dataDecryptor), encryptedSessionKey);
+            integrityProtectedStreams.add(integrityProtected);
+            return integrityProtected;
+        }
+        return encryptedSessionKey.getDataStream(dataDecryptor);
     }
 
     private void initOnePassSignatures(@Nonnull PGPOnePassSignatureList onePassSignatureList) throws PGPException {

pgpainless-core/src/main/java/org/pgpainless/util/IntegrityProtectedInputStream.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2021 Paul Schaub.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pgpainless.util;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+import org.bouncycastle.openpgp.PGPEncryptedData;
+import org.bouncycastle.openpgp.PGPException;
+
+public class IntegrityProtectedInputStream extends InputStream {
+
+    private final InputStream inputStream;
+    private final PGPEncryptedData encryptedData;
+
+    public IntegrityProtectedInputStream(InputStream inputStream, PGPEncryptedData encryptedData) {
+        this.inputStream = inputStream;
+        this.encryptedData = encryptedData;
+    }
+
+    @Override
+    public int read() throws IOException {
+        return inputStream.read();
+    }
+
+    @Override
+    public void close() throws IOException {
+        if (encryptedData.isIntegrityProtected()) {
+            try {
+                if (!encryptedData.verify()) {
+                    throw new PGPException("Modification Detection failed.");
+                }
+            } catch (PGPException e) {
+                throw new IOException(e);
+            }
+        }
+    }
+}