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, 76 insertions, 278 deletions

diff --git a/OpenKeychain/src/main/java/org/spongycastle/openpgp/operator/jcajce/CachingDataDecryptorFactory.java b/OpenKeychain/src/main/java/org/spongycastle/openpgp/operator/jcajce/CachingDataDecryptorFactory.java
new file mode 100644
index 000000000..d35f1d751
--- /dev/null
+++ b/OpenKeychain/src/main/java/org/spongycastle/openpgp/operator/jcajce/CachingDataDecryptorFactory.java
@@ -0,0 +1,76 @@
+/**
+ * Copyright (c) 2013-2014 Philipp Jakubeit, Signe Rüsch, Dominik Schürmann
+ *
+ * Licensed under the Bouncy Castle License (MIT license). See LICENSE file for details.
+ */
+
+package org.spongycastle.openpgp.operator.jcajce;
+
+import org.spongycastle.jcajce.util.NamedJcaJceHelper;
+import org.spongycastle.openpgp.PGPException;
+import org.spongycastle.openpgp.PGPPublicKeyEncryptedData;
+import org.spongycastle.openpgp.operator.PGPDataDecryptor;
+import org.spongycastle.openpgp.operator.PublicKeyDataDecryptorFactory;
+
+import java.nio.ByteBuffer;
+import java.util.Map;
+
+public class CachingDataDecryptorFactory implements PublicKeyDataDecryptorFactory
+{
+    private final PublicKeyDataDecryptorFactory mWrappedDecryptor;
+    private final Map<ByteBuffer, byte[]> mSessionKeyCache;
+
+    private OperatorHelper mOperatorHelper;
+
+    public CachingDataDecryptorFactory(String providerName,
+            final Map<ByteBuffer,byte[]> sessionKeyCache)
+    {
+        mWrappedDecryptor = null;
+        mSessionKeyCache = sessionKeyCache;
+
+        mOperatorHelper = new OperatorHelper(new NamedJcaJceHelper(providerName));
+    }
+
+    public CachingDataDecryptorFactory(PublicKeyDataDecryptorFactory wrapped,
+            final Map<ByteBuffer,byte[]> sessionKeyCache)
+    {
+        mWrappedDecryptor = wrapped;
+        mSessionKeyCache = sessionKeyCache;
+
+    }
+
+    public boolean hasCachedSessionData(PGPPublicKeyEncryptedData encData) throws PGPException {
+        ByteBuffer bi = ByteBuffer.wrap(encData.getSessionKey()[0]);
+        return mSessionKeyCache.containsKey(bi);
+    }
+
+    public Map<ByteBuffer, byte[]> getCachedSessionKeys() {
+        return mSessionKeyCache;
+    }
+
+    public boolean canDecrypt() {
+        return mWrappedDecryptor != null;
+    }
+
+    @Override
+    public byte[] recoverSessionData(int keyAlgorithm, byte[][] secKeyData) throws PGPException {
+        ByteBuffer bi = ByteBuffer.wrap(secKeyData[0]);  // encoded MPI
+        if (mSessionKeyCache.containsKey(bi)) {
+            return mSessionKeyCache.get(bi);
+        }
+
+        byte[] sessionData = mWrappedDecryptor.recoverSessionData(keyAlgorithm, secKeyData);
+        mSessionKeyCache.put(bi, sessionData);
+        return sessionData;
+    }
+
+    @Override
+    public PGPDataDecryptor createDataDecryptor(boolean withIntegrityPacket, int encAlgorithm, byte[] key)
+            throws PGPException {
+        if (mWrappedDecryptor != null) {
+            return mWrappedDecryptor.createDataDecryptor(withIntegrityPacket, encAlgorithm, key);
+        }
+        return mOperatorHelper.createDataDecryptor(withIntegrityPacket, encAlgorithm, key);
+    }
+
+}
diff --git a/OpenKeychain/src/main/java/org/spongycastle/openpgp/operator/jcajce/NfcSyncPublicKeyDataDecryptorFactoryBuilder.java b/OpenKeychain/src/main/java/org/spongycastle/openpgp/operator/jcajce/NfcSyncPublicKeyDataDecryptorFactoryBuilder.java
deleted file mode 100644
index 067bb3e19..000000000
--- a/OpenKeychain/src/main/java/org/spongycastle/openpgp/operator/jcajce/NfcSyncPublicKeyDataDecryptorFactoryBuilder.java
+++ /dev/null
@@ -1,278 +0,0 @@
-/**
- * Copyright (c) 2013-2014 Philipp Jakubeit, Signe Rüsch, Dominik Schürmann
- *
- * Licensed under the Bouncy Castle License (MIT license). See LICENSE file for details.
- */
-
-package org.spongycastle.openpgp.operator.jcajce;
-
-import org.spongycastle.bcpg.PublicKeyAlgorithmTags;
-import org.spongycastle.jcajce.util.DefaultJcaJceHelper;
-import org.spongycastle.jcajce.util.NamedJcaJceHelper;
-import org.spongycastle.jcajce.util.ProviderJcaJceHelper;
-import org.spongycastle.openpgp.PGPException;
-import org.spongycastle.openpgp.PGPPublicKey;
-import org.spongycastle.openpgp.operator.PGPDataDecryptor;
-import org.spongycastle.openpgp.operator.PublicKeyDataDecryptorFactory;
-
-import java.nio.ByteBuffer;
-import java.security.Provider;
-import java.util.Map;
-
-
-/**
- * This class is based on JcePublicKeyDataDecryptorFactoryBuilder
- *
- */
-public class NfcSyncPublicKeyDataDecryptorFactoryBuilder
-{
-    private OperatorHelper helper = new OperatorHelper(new DefaultJcaJceHelper());
-    private OperatorHelper contentHelper = new OperatorHelper(new DefaultJcaJceHelper());
-    private JcaPGPKeyConverter keyConverter = new JcaPGPKeyConverter();
-//    private JcaPGPDigestCalculatorProviderBuilder digestCalculatorProviderBuilder = new JcaPGPDigestCalculatorProviderBuilder();
-//    private JcaKeyFingerprintCalculator fingerprintCalculator = new JcaKeyFingerprintCalculator();
-
-    public static class NfcInteractionNeeded extends RuntimeException
-    {
-        public byte[] encryptedSessionKey;
-
-        public NfcInteractionNeeded(byte[] encryptedSessionKey)
-        {
-            super("NFC interaction required!");
-            this.encryptedSessionKey = encryptedSessionKey;
-        }
-    }
-
-    public NfcSyncPublicKeyDataDecryptorFactoryBuilder()
-    {
-    }
-
-    /**
-     * Set the provider object to use for creating cryptographic primitives in the resulting factory the builder produces.
-     *
-     * @param provider  provider object for cryptographic primitives.
-     * @return  the current builder.
-     */
-    public NfcSyncPublicKeyDataDecryptorFactoryBuilder setProvider(Provider provider)
-    {
-        this.helper = new OperatorHelper(new ProviderJcaJceHelper(provider));
-        keyConverter.setProvider(provider);
-        this.contentHelper = helper;
-
-        return this;
-    }
-
-    /**
-     * Set the provider name to use for creating cryptographic primitives in the resulting factory the builder produces.
-     *
-     * @param providerName  the name of the provider to reference for cryptographic primitives.
-     * @return  the current builder.
-     */
-    public NfcSyncPublicKeyDataDecryptorFactoryBuilder setProvider(String providerName)
-    {
-        this.helper = new OperatorHelper(new NamedJcaJceHelper(providerName));
-        keyConverter.setProvider(providerName);
-        this.contentHelper = helper;
-
-        return this;
-    }
-
-    public NfcSyncPublicKeyDataDecryptorFactoryBuilder setContentProvider(Provider provider)
-    {
-        this.contentHelper = new OperatorHelper(new ProviderJcaJceHelper(provider));
-
-        return this;
-    }
-
-    public NfcSyncPublicKeyDataDecryptorFactoryBuilder setContentProvider(String providerName)
-    {
-        this.contentHelper = new OperatorHelper(new NamedJcaJceHelper(providerName));
-
-        return this;
-    }
-
-    public PublicKeyDataDecryptorFactory build(final Map<ByteBuffer,byte[]> nfcDecryptedMap) {
-        return new PublicKeyDataDecryptorFactory()
-        {
-            public byte[] recoverSessionData(int keyAlgorithm, byte[][] secKeyData)
-                    throws PGPException
-            {
-                if (keyAlgorithm == PublicKeyAlgorithmTags.ECDH)
-                {
-                    throw new PGPException("ECDH not supported!");
-                }
-
-                return decryptSessionData(keyAlgorithm, secKeyData, nfcDecryptedMap);
-            }
-
-            public PGPDataDecryptor createDataDecryptor(boolean withIntegrityPacket, int encAlgorithm, byte[] key)
-                    throws PGPException
-            {
-                return contentHelper.createDataDecryptor(withIntegrityPacket, encAlgorithm, key);
-            }
-        };
-    }
-
-//    public PublicKeyDataDecryptorFactory build(final PrivateKey privKey)
-//    {
-//        return new PublicKeyDataDecryptorFactory()
-//        {
-//            public byte[] recoverSessionData(int keyAlgorithm, byte[][] secKeyData)
-//                    throws PGPException
-//            {
-//                if (keyAlgorithm == PublicKeyAlgorithmTags.ECDH)
-//                {
-//                    throw new PGPException("ECDH requires use of PGPPrivateKey for decryption");
-//                }
-//                return decryptSessionData(keyAlgorithm, privKey, secKeyData);
-//            }
-//
-//            public PGPDataDecryptor createDataDecryptor(boolean withIntegrityPacket, int encAlgorithm, byte[] key)
-//                    throws PGPException
-//            {
-//                return contentHelper.createDataDecryptor(withIntegrityPacket, encAlgorithm, key);
-//            }
-//        };
-//    }
-
-//    public PublicKeyDataDecryptorFactory build(final PGPPrivateKey privKey, final byte[] nfcDecrypted)
-//    {
-//        return new PublicKeyDataDecryptorFactory()
-//        {
-//            public byte[] recoverSessionData(int keyAlgorithm, byte[][] secKeyData)
-//                    throws PGPException
-//            {
-//                if (keyAlgorithm == PublicKeyAlgorithmTags.ECDH)
-//                {
-//                    return decryptSessionData(privKey.getPrivateKeyDataPacket(), privKey.getPublicKeyPacket(), secKeyData);
-//                }
-//
-//                return decryptSessionData(keyAlgorithm, keyConverter.getPrivateKey(privKey), secKeyData, nfcDecrypted);
-//            }
-//
-//            public PGPDataDecryptor createDataDecryptor(boolean withIntegrityPacket, int encAlgorithm, byte[] key)
-//                    throws PGPException
-//            {
-//                return contentHelper.createDataDecryptor(withIntegrityPacket, encAlgorithm, key);
-//            }
-//        };
-//    }
-
-//    private byte[] decryptSessionData(BCPGKey privateKeyPacket, PublicKeyPacket pubKeyData, byte[][] secKeyData)
-//            throws PGPException
-//    {
-//        ECDHPublicBCPGKey ecKey = (ECDHPublicBCPGKey)pubKeyData.getKey();
-//        X9ECParameters x9Params = NISTNamedCurves.getByOID(ecKey.getCurveOID());
-//
-//        byte[] enc = secKeyData[0];
-//
-//        int pLen = ((((enc[0] & 0xff) << 8) + (enc[1] & 0xff)) + 7) / 8;
-//        byte[] pEnc = new byte[pLen];
-//
-//        System.arraycopy(enc, 2, pEnc, 0, pLen);
-//
-//        byte[] keyEnc = new byte[enc[pLen + 2]];
-//
-//        System.arraycopy(enc, 2 + pLen + 1, keyEnc, 0, keyEnc.length);
-//
-//        Cipher c = helper.createKeyWrapper(ecKey.getSymmetricKeyAlgorithm());
-//
-//        ECPoint S = x9Params.getCurve().decodePoint(pEnc).multiply(((ECSecretBCPGKey)privateKeyPacket).getX()).normalize();
-//
-//        RFC6637KDFCalculator rfc6637KDFCalculator = new RFC6637KDFCalculator(digestCalculatorProviderBuilder.build().get(ecKey.getHashAlgorithm()), ecKey.getSymmetricKeyAlgorithm());
-//        Key key = new SecretKeySpec(rfc6637KDFCalculator.createKey(ecKey.getCurveOID(), S, fingerprintCalculator.calculateFingerprint(pubKeyData)), "AESWrap");
-//
-//        try
-//        {
-//            c.init(Cipher.UNWRAP_MODE, key);
-//
-//            Key paddedSessionKey = c.unwrap(keyEnc, "Session", Cipher.SECRET_KEY);
-//
-//            return PGPPad.unpadSessionData(paddedSessionKey.getEncoded());
-//        }
-//        catch (InvalidKeyException e)
-//        {
-//            throw new PGPException("error setting asymmetric cipher", e);
-//        }
-//        catch (NoSuchAlgorithmException e)
-//        {
-//            throw new PGPException("error setting asymmetric cipher", e);
-//        }
-//    }
-
-    private byte[] decryptSessionData(int keyAlgorithm, byte[][] secKeyData,
-            Map<ByteBuffer,byte[]> nfcDecryptedMap)
-        throws PGPException
-    {
-//        Cipher c1 = helper.createPublicKeyCipher(keyAlgorithm);
-//
-//        try
-//        {
-//            c1.init(Cipher.DECRYPT_MODE, privKey);
-//        }
-//        catch (InvalidKeyException e)
-//        {
-//            throw new PGPException("error setting asymmetric cipher", e);
-//        }
-
-        if (keyAlgorithm == PGPPublicKey.RSA_ENCRYPT
-                || keyAlgorithm == PGPPublicKey.RSA_GENERAL)
-        {
-            ByteBuffer bi = ByteBuffer.wrap(secKeyData[0]);  // encoded MPI
-
-            if (nfcDecryptedMap.containsKey(bi)) {
-                return nfcDecryptedMap.get(bi);
-            } else {
-                // catch this when decryptSessionData() is executed and divert digest to card,
-                // when doing the operation again reuse nfcDecrypted
-                throw new NfcInteractionNeeded(bi.array());
-            }
-
-//            c1.update(bi, 2, bi.length - 2);
-        }
-        else
-        {
-            throw new PGPException("ElGamal not supported!");
-
-//            ElGamalKey k = (ElGamalKey)privKey;
-//            int size = (k.getParameters().getP().bitLength() + 7) / 8;
-//            byte[] tmp = new byte[size];
-//
-//            byte[] bi = secKeyData[0]; // encoded MPI
-//            if (bi.length - 2 > size)  // leading Zero? Shouldn't happen but...
-//            {
-//                c1.update(bi, 3, bi.length - 3);
-//            }
-//            else
-//            {
-//                System.arraycopy(bi, 2, tmp, tmp.length - (bi.length - 2), bi.length - 2);
-//                c1.update(tmp);
-//            }
-//
-//            bi = secKeyData[1];  // encoded MPI
-//            for (int i = 0; i != tmp.length; i++)
-//            {
-//                tmp[i] = 0;
-//            }
-//
-//            if (bi.length - 2 > size) // leading Zero? Shouldn't happen but...
-//            {
-//                c1.update(bi, 3, bi.length - 3);
-//            }
-//            else
-//            {
-//                System.arraycopy(bi, 2, tmp, tmp.length - (bi.length - 2), bi.length - 2);
-//                c1.update(tmp);
-//            }
-        }
-
-//        try
-//        {
-//            return c1.doFinal();
-//        }
-//        catch (Exception e)
-//        {
-//            throw new PGPException("exception decrypting session data", e);
-//        }
-    }
-}