introduce CachingDataDecryptorFactory towards cached session keys

this commit introduces the CachingDataDecryptorFactory, which wraps
a DataDecryptorFactory but supports caching of decrypted session keys.

this change also gets rid of runtimeexception based control flow in
PgpDecryptVerify.

2 files changed, 33 insertions, 28 deletions

diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/CanonicalizedSecretKey.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/CanonicalizedSecretKey.java
index 17d342341..31a3925da 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/CanonicalizedSecretKey.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/CanonicalizedSecretKey.java
@@ -21,23 +21,18 @@ package org.sufficientlysecure.keychain.pgp;
 import org.spongycastle.bcpg.S2K;
 import org.spongycastle.openpgp.PGPException;
 import org.spongycastle.openpgp.PGPPrivateKey;
-import org.spongycastle.openpgp.PGPPublicKey;
-import org.spongycastle.openpgp.PGPPublicKeyRing;
 import org.spongycastle.openpgp.PGPSecretKey;
 import org.spongycastle.openpgp.PGPSignature;
 import org.spongycastle.openpgp.PGPSignatureGenerator;
 import org.spongycastle.openpgp.PGPSignatureSubpacketGenerator;
-import org.spongycastle.openpgp.PGPSignatureSubpacketVector;
-import org.spongycastle.openpgp.PGPUserAttributeSubpacketVector;
 import org.spongycastle.openpgp.operator.PBESecretKeyDecryptor;
 import org.spongycastle.openpgp.operator.PGPContentSignerBuilder;
-import org.spongycastle.openpgp.operator.PublicKeyDataDecryptorFactory;
+import org.spongycastle.openpgp.operator.jcajce.CachingDataDecryptorFactory;
 import org.spongycastle.openpgp.operator.jcajce.JcaPGPContentSignerBuilder;
 import org.spongycastle.openpgp.operator.jcajce.JcaPGPKeyConverter;
 import org.spongycastle.openpgp.operator.jcajce.JcePBESecretKeyDecryptorBuilder;
 import org.spongycastle.openpgp.operator.jcajce.JcePublicKeyDataDecryptorFactoryBuilder;
 import org.spongycastle.openpgp.operator.jcajce.NfcSyncPGPContentSignerBuilder;
-import org.spongycastle.openpgp.operator.jcajce.NfcSyncPublicKeyDataDecryptorFactoryBuilder;
 import org.sufficientlysecure.keychain.Constants;
 import org.sufficientlysecure.keychain.pgp.exception.PgpGeneralException;
 import org.sufficientlysecure.keychain.pgp.exception.PgpKeyNotFoundException;
@@ -51,7 +46,6 @@ import java.security.interfaces.RSAPrivateCrtKey;
 import java.util.ArrayList;
 import java.util.Date;
 import java.util.HashMap;
-import java.util.List;
 import java.util.Map;
 
 
@@ -270,19 +264,20 @@ public class CanonicalizedSecretKey extends CanonicalizedPublicKey {
         }
     }
 
-    public PublicKeyDataDecryptorFactory getDecryptorFactory(CryptoInputParcel cryptoInput) {
+    public CachingDataDecryptorFactory getCachingDecryptorFactory(CryptoInputParcel cryptoInput) {
         if (mPrivateKeyState == PRIVATE_KEY_STATE_LOCKED) {
             throw new PrivateKeyNotUnlockedException();
         }
 
         if (mPrivateKeyState == PRIVATE_KEY_STATE_DIVERT_TO_CARD) {
-            return new NfcSyncPublicKeyDataDecryptorFactoryBuilder()
-                    .setProvider(Constants.BOUNCY_CASTLE_PROVIDER_NAME).build(
-                            cryptoInput.getCryptoData()
-                    );
+            return new CachingDataDecryptorFactory(
+                    Constants.BOUNCY_CASTLE_PROVIDER_NAME,
+                    cryptoInput.getCryptoData());
         } else {
-            return new JcePublicKeyDataDecryptorFactoryBuilder()
-                    .setProvider(Constants.BOUNCY_CASTLE_PROVIDER_NAME).build(mPrivateKey);
+            return new CachingDataDecryptorFactory(
+                    new JcePublicKeyDataDecryptorFactoryBuilder()
+                            .setProvider(Constants.BOUNCY_CASTLE_PROVIDER_NAME).build(mPrivateKey),
+                    cryptoInput.getCryptoData());
         }
     }
 
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpDecryptVerify.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpDecryptVerify.java
index 4382c9fae..235b0a671 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpDecryptVerify.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpDecryptVerify.java
@@ -24,6 +24,7 @@ import android.webkit.MimeTypeMap;
 import org.openintents.openpgp.OpenPgpMetadata;
 import org.openintents.openpgp.OpenPgpSignatureResult;
 import org.spongycastle.bcpg.ArmoredInputStream;
+import org.spongycastle.bcpg.PublicKeyEncSessionPacket;
 import org.spongycastle.openpgp.PGPCompressedData;
 import org.spongycastle.openpgp.PGPEncryptedData;
 import org.spongycastle.openpgp.PGPEncryptedDataList;
@@ -40,11 +41,10 @@ import org.spongycastle.openpgp.PGPUtil;
 import org.spongycastle.openpgp.jcajce.JcaPGPObjectFactory;
 import org.spongycastle.openpgp.operator.PBEDataDecryptorFactory;
 import org.spongycastle.openpgp.operator.PGPDigestCalculatorProvider;
-import org.spongycastle.openpgp.operator.PublicKeyDataDecryptorFactory;
+import org.spongycastle.openpgp.operator.jcajce.CachingDataDecryptorFactory;
 import org.spongycastle.openpgp.operator.jcajce.JcaPGPContentVerifierBuilderProvider;
 import org.spongycastle.openpgp.operator.jcajce.JcaPGPDigestCalculatorProviderBuilder;
 import org.spongycastle.openpgp.operator.jcajce.JcePBEDataDecryptorFactoryBuilder;
-import org.spongycastle.openpgp.operator.jcajce.NfcSyncPublicKeyDataDecryptorFactoryBuilder;
 import org.sufficientlysecure.keychain.Constants;
 import org.sufficientlysecure.keychain.R;
 import org.sufficientlysecure.keychain.operations.BaseOperation;
@@ -541,24 +541,33 @@ public class PgpDecryptVerify extends BaseOperation {
             currentProgress += 2;
             updateProgress(R.string.progress_preparing_streams, currentProgress, 100);
 
-            try {
-                PublicKeyDataDecryptorFactory decryptorFactory
-                        = secretEncryptionKey.getDecryptorFactory(cryptoInput);
-                try {
-                    clear = encryptedDataAsymmetric.getDataStream(decryptorFactory);
-                } catch (PGPKeyValidationException | ArrayIndexOutOfBoundsException e) {
-                    log.add(LogType.MSG_DC_ERROR_CORRUPT_DATA, indent + 1);
-                    return new DecryptVerifyResult(DecryptVerifyResult.RESULT_ERROR, log);
-                }
+            CachingDataDecryptorFactory decryptorFactory
+                    = secretEncryptionKey.getCachingDecryptorFactory(cryptoInput);
+
+            // special case: if the decryptor does not have a session key cached for this encrypted
+            // data, and can't actually decrypt on its own, return a pending intent
+            if (!decryptorFactory.canDecrypt()
+                    && !decryptorFactory.hasCachedSessionData(encryptedDataAsymmetric)) {
 
-                symmetricEncryptionAlgo = encryptedDataAsymmetric.getSymmetricAlgorithm(decryptorFactory);
-            } catch (NfcSyncPublicKeyDataDecryptorFactoryBuilder.NfcInteractionNeeded e) {
                 log.add(LogType.MSG_DC_PENDING_NFC, indent + 1);
                 return new DecryptVerifyResult(log, RequiredInputParcel.createNfcDecryptOperation(
                         secretEncryptionKey.getRing().getMasterKeyId(),
-                        secretEncryptionKey.getKeyId(), e.encryptedSessionKey
+                        secretEncryptionKey.getKeyId(), encryptedDataAsymmetric.getSessionKey()[0]
                 ));
+
             }
+
+            try {
+                clear = encryptedDataAsymmetric.getDataStream(decryptorFactory);
+            } catch (PGPKeyValidationException | ArrayIndexOutOfBoundsException e) {
+                log.add(LogType.MSG_DC_ERROR_CORRUPT_DATA, indent + 1);
+                return new DecryptVerifyResult(DecryptVerifyResult.RESULT_ERROR, log);
+            }
+
+            symmetricEncryptionAlgo = encryptedDataAsymmetric.getSymmetricAlgorithm(decryptorFactory);
+
+            cryptoInput.addCryptoData(decryptorFactory.getCachedSessionKeys());
+
             encryptedData = encryptedDataAsymmetric;
         } else {
             // there wasn't even any useful data
@@ -821,6 +830,7 @@ public class PgpDecryptVerify extends BaseOperation {
         // Return a positive result, with metadata and verification info
         DecryptVerifyResult result =
                 new DecryptVerifyResult(DecryptVerifyResult.RESULT_OK, log);
+        result.setCachedCryptoInputParcel(cryptoInput);
         result.setDecryptMetadata(metadata);
         result.setSignatureResult(signatureResultBuilder.build());
         result.setCharset(charset);