diff --git a/build.gradle b/build.gradle
index 5802b4b9..906f6060 100644
--- a/build.gradle
+++ b/build.gradle
@@ -34,6 +34,6 @@ repositories {
 
 dependencies {
     testCompile group: 'junit', name: 'junit', version: '4.12'
-    compile 'org.bouncycastle:bcprov-debug-jdk15on:1.59'
+    compile 'org.bouncycastle:bcprov-jdk15on:1.59'
     compile 'org.bouncycastle:bcpg-jdk15on:1.59'
 }
diff --git a/src/main/java/org/pgpainless/pgpainless/PGPainless.java b/src/main/java/org/pgpainless/pgpainless/PGPainless.java
index fcc17f1e..5465b6e1 100644
--- a/src/main/java/org/pgpainless/pgpainless/PGPainless.java
+++ b/src/main/java/org/pgpainless/pgpainless/PGPainless.java
@@ -22,7 +22,7 @@ import org.pgpainless.pgpainless.decryption_verification.DecryptionBuilder;
 import org.pgpainless.pgpainless.decryption_verification.DecryptionStream;
 import org.pgpainless.pgpainless.encryption_signing.EncryptionBuilder;
 import org.pgpainless.pgpainless.encryption_signing.EncryptionStream;
-import org.pgpainless.pgpainless.key.KeyRingReader;
+import org.pgpainless.pgpainless.key.parsing.KeyRingReader;
 import org.pgpainless.pgpainless.key.generation.KeyRingBuilder;
 import org.pgpainless.pgpainless.symmetric_encryption.SymmetricEncryptorDecryptor;
 
diff --git a/src/main/java/org/pgpainless/pgpainless/decryption_verification/DecryptionBuilder.java b/src/main/java/org/pgpainless/pgpainless/decryption_verification/DecryptionBuilder.java
index 5ada109f..0823e095 100644
--- a/src/main/java/org/pgpainless/pgpainless/decryption_verification/DecryptionBuilder.java
+++ b/src/main/java/org/pgpainless/pgpainless/decryption_verification/DecryptionBuilder.java
@@ -25,7 +25,7 @@ import org.bouncycastle.openpgp.PGPException;
 import org.bouncycastle.openpgp.PGPPublicKeyRing;
 import org.bouncycastle.openpgp.PGPPublicKeyRingCollection;
 import org.bouncycastle.openpgp.PGPSecretKeyRingCollection;
-import org.pgpainless.pgpainless.key.SecretKeyRingProtector;
+import org.pgpainless.pgpainless.key.protection.SecretKeyRingProtector;
 
 public class DecryptionBuilder implements DecryptionBuilderInterface {
 
diff --git a/src/main/java/org/pgpainless/pgpainless/decryption_verification/DecryptionBuilderInterface.java b/src/main/java/org/pgpainless/pgpainless/decryption_verification/DecryptionBuilderInterface.java
index 2339c53c..081c68bf 100644
--- a/src/main/java/org/pgpainless/pgpainless/decryption_verification/DecryptionBuilderInterface.java
+++ b/src/main/java/org/pgpainless/pgpainless/decryption_verification/DecryptionBuilderInterface.java
@@ -23,7 +23,7 @@ import org.bouncycastle.openpgp.PGPException;
 import org.bouncycastle.openpgp.PGPPublicKeyRing;
 import org.bouncycastle.openpgp.PGPPublicKeyRingCollection;
 import org.bouncycastle.openpgp.PGPSecretKeyRingCollection;
-import org.pgpainless.pgpainless.key.SecretKeyRingProtector;
+import org.pgpainless.pgpainless.key.protection.SecretKeyRingProtector;
 
 public interface DecryptionBuilderInterface {
 
diff --git a/src/main/java/org/pgpainless/pgpainless/decryption_verification/DecryptionStreamFactory.java b/src/main/java/org/pgpainless/pgpainless/decryption_verification/DecryptionStreamFactory.java
index bd9c44b9..f89d5573 100644
--- a/src/main/java/org/pgpainless/pgpainless/decryption_verification/DecryptionStreamFactory.java
+++ b/src/main/java/org/pgpainless/pgpainless/decryption_verification/DecryptionStreamFactory.java
@@ -48,7 +48,7 @@ import org.bouncycastle.openpgp.operator.bc.BcPGPContentVerifierBuilderProvider;
 import org.bouncycastle.openpgp.operator.bc.BcPublicKeyDataDecryptorFactory;
 import org.pgpainless.pgpainless.algorithm.CompressionAlgorithm;
 import org.pgpainless.pgpainless.algorithm.SymmetricKeyAlgorithm;
-import org.pgpainless.pgpainless.key.SecretKeyRingProtector;
+import org.pgpainless.pgpainless.key.protection.SecretKeyRingProtector;
 
 public final class DecryptionStreamFactory {
 
diff --git a/src/main/java/org/pgpainless/pgpainless/encryption_signing/EncryptionBuilder.java b/src/main/java/org/pgpainless/pgpainless/encryption_signing/EncryptionBuilder.java
index 8cc0b801..9c329873 100644
--- a/src/main/java/org/pgpainless/pgpainless/encryption_signing/EncryptionBuilder.java
+++ b/src/main/java/org/pgpainless/pgpainless/encryption_signing/EncryptionBuilder.java
@@ -32,7 +32,7 @@ import org.bouncycastle.openpgp.PGPSecretKeyRingCollection;
 import org.pgpainless.pgpainless.algorithm.CompressionAlgorithm;
 import org.pgpainless.pgpainless.algorithm.HashAlgorithm;
 import org.pgpainless.pgpainless.algorithm.SymmetricKeyAlgorithm;
-import org.pgpainless.pgpainless.key.SecretKeyRingProtector;
+import org.pgpainless.pgpainless.key.protection.SecretKeyRingProtector;
 import org.pgpainless.pgpainless.key.selection.key.PublicKeySelectionStrategy;
 import org.pgpainless.pgpainless.key.selection.key.SecretKeySelectionStrategy;
 import org.pgpainless.pgpainless.key.selection.key.impl.And;
diff --git a/src/main/java/org/pgpainless/pgpainless/encryption_signing/EncryptionBuilderInterface.java b/src/main/java/org/pgpainless/pgpainless/encryption_signing/EncryptionBuilderInterface.java
index 5420a2ca..51cd37a2 100644
--- a/src/main/java/org/pgpainless/pgpainless/encryption_signing/EncryptionBuilderInterface.java
+++ b/src/main/java/org/pgpainless/pgpainless/encryption_signing/EncryptionBuilderInterface.java
@@ -29,7 +29,7 @@ import org.pgpainless.pgpainless.SecretKeyNotFoundException;
 import org.pgpainless.pgpainless.algorithm.CompressionAlgorithm;
 import org.pgpainless.pgpainless.algorithm.HashAlgorithm;
 import org.pgpainless.pgpainless.algorithm.SymmetricKeyAlgorithm;
-import org.pgpainless.pgpainless.key.SecretKeyRingProtector;
+import org.pgpainless.pgpainless.key.protection.SecretKeyRingProtector;
 import org.pgpainless.pgpainless.key.selection.keyring.PublicKeyRingSelectionStrategy;
 import org.pgpainless.pgpainless.key.selection.keyring.SecretKeyRingSelectionStrategy;
 import org.pgpainless.pgpainless.util.MultiMap;
diff --git a/src/main/java/org/pgpainless/pgpainless/key/KeyRingReader.java b/src/main/java/org/pgpainless/pgpainless/key/parsing/KeyRingReader.java
similarity index 98%
rename from src/main/java/org/pgpainless/pgpainless/key/KeyRingReader.java
rename to src/main/java/org/pgpainless/pgpainless/key/parsing/KeyRingReader.java
index af601905..37d2f18d 100644
--- a/src/main/java/org/pgpainless/pgpainless/key/KeyRingReader.java
+++ b/src/main/java/org/pgpainless/pgpainless/key/parsing/KeyRingReader.java
@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.pgpainless.pgpainless.key;
+package org.pgpainless.pgpainless.key.parsing;
 
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
diff --git a/src/main/java/org/pgpainless/pgpainless/key/parsing/package-info.java b/src/main/java/org/pgpainless/pgpainless/key/parsing/package-info.java
new file mode 100644
index 00000000..ecc226f9
--- /dev/null
+++ b/src/main/java/org/pgpainless/pgpainless/key/parsing/package-info.java
@@ -0,0 +1,19 @@
+/*
+ * Copyright 2018 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.
+ */
+/**
+ * Classes related to OpenPGP key reading.
+ */
+package org.pgpainless.pgpainless.key.parsing;
diff --git a/src/main/java/org/pgpainless/pgpainless/key/KeyRingProtectionSettings.java b/src/main/java/org/pgpainless/pgpainless/key/protection/KeyRingProtectionSettings.java
similarity index 96%
rename from src/main/java/org/pgpainless/pgpainless/key/KeyRingProtectionSettings.java
rename to src/main/java/org/pgpainless/pgpainless/key/protection/KeyRingProtectionSettings.java
index 5962bbc1..7d1d0a87 100644
--- a/src/main/java/org/pgpainless/pgpainless/key/KeyRingProtectionSettings.java
+++ b/src/main/java/org/pgpainless/pgpainless/key/protection/KeyRingProtectionSettings.java
@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.pgpainless.pgpainless.key;
+package org.pgpainless.pgpainless.key.protection;
 
 import org.pgpainless.pgpainless.algorithm.HashAlgorithm;
 import org.pgpainless.pgpainless.algorithm.SymmetricKeyAlgorithm;
diff --git a/src/main/java/org/pgpainless/pgpainless/key/PassphraseMapKeyRingProtector.java b/src/main/java/org/pgpainless/pgpainless/key/protection/PassphraseMapKeyRingProtector.java
similarity index 98%
rename from src/main/java/org/pgpainless/pgpainless/key/PassphraseMapKeyRingProtector.java
rename to src/main/java/org/pgpainless/pgpainless/key/protection/PassphraseMapKeyRingProtector.java
index ba895ed1..e2565d95 100644
--- a/src/main/java/org/pgpainless/pgpainless/key/PassphraseMapKeyRingProtector.java
+++ b/src/main/java/org/pgpainless/pgpainless/key/protection/PassphraseMapKeyRingProtector.java
@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.pgpainless.pgpainless.key;
+package org.pgpainless.pgpainless.key.protection;
 
 import java.util.HashMap;
 import java.util.Map;
diff --git a/src/main/java/org/pgpainless/pgpainless/key/SecretKeyRingProtector.java b/src/main/java/org/pgpainless/pgpainless/key/protection/SecretKeyRingProtector.java
similarity index 96%
rename from src/main/java/org/pgpainless/pgpainless/key/SecretKeyRingProtector.java
rename to src/main/java/org/pgpainless/pgpainless/key/protection/SecretKeyRingProtector.java
index 1427ea81..ff820ce0 100644
--- a/src/main/java/org/pgpainless/pgpainless/key/SecretKeyRingProtector.java
+++ b/src/main/java/org/pgpainless/pgpainless/key/protection/SecretKeyRingProtector.java
@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.pgpainless.pgpainless.key;
+package org.pgpainless.pgpainless.key.protection;
 
 import org.bouncycastle.openpgp.PGPException;
 import org.bouncycastle.openpgp.operator.PBESecretKeyDecryptor;
diff --git a/src/main/java/org/pgpainless/pgpainless/key/UnprotectedKeysProtector.java b/src/main/java/org/pgpainless/pgpainless/key/protection/UnprotectedKeysProtector.java
similarity index 95%
rename from src/main/java/org/pgpainless/pgpainless/key/UnprotectedKeysProtector.java
rename to src/main/java/org/pgpainless/pgpainless/key/protection/UnprotectedKeysProtector.java
index 8c15386a..82711013 100644
--- a/src/main/java/org/pgpainless/pgpainless/key/UnprotectedKeysProtector.java
+++ b/src/main/java/org/pgpainless/pgpainless/key/protection/UnprotectedKeysProtector.java
@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.pgpainless.pgpainless.key;
+package org.pgpainless.pgpainless.key.protection;
 
 import org.bouncycastle.openpgp.operator.PBESecretKeyDecryptor;
 import org.bouncycastle.openpgp.operator.PBESecretKeyEncryptor;
diff --git a/src/main/java/org/pgpainless/pgpainless/key/protection/package-info.java b/src/main/java/org/pgpainless/pgpainless/key/protection/package-info.java
new file mode 100644
index 00000000..57f95712
--- /dev/null
+++ b/src/main/java/org/pgpainless/pgpainless/key/protection/package-info.java
@@ -0,0 +1,19 @@
+/*
+ * Copyright 2018 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.
+ */
+/**
+ * Classes related to OpenPGP secret key password protection.
+ */
+package org.pgpainless.pgpainless.key.protection;
diff --git a/src/main/java/org/pgpainless/pgpainless/util/BCUtil.java b/src/main/java/org/pgpainless/pgpainless/util/BCUtil.java
index 9ac6fd6b..33583bd8 100644
--- a/src/main/java/org/pgpainless/pgpainless/util/BCUtil.java
+++ b/src/main/java/org/pgpainless/pgpainless/util/BCUtil.java
@@ -30,7 +30,12 @@ import java.util.Set;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
+import org.bouncycastle.bcpg.S2K;
+import org.bouncycastle.bcpg.SecretKeyPacket;
+import org.bouncycastle.bcpg.SecretSubkeyPacket;
+import org.bouncycastle.bcpg.SymmetricKeyAlgorithmTags;
 import org.bouncycastle.openpgp.PGPException;
+import org.bouncycastle.openpgp.PGPKeyRing;
 import org.bouncycastle.openpgp.PGPPublicKey;
 import org.bouncycastle.openpgp.PGPPublicKeyRing;
 import org.bouncycastle.openpgp.PGPPublicKeyRingCollection;
@@ -214,6 +219,18 @@ public class BCUtil {
         return null;
     }
 
+    public static PGPPublicKey getMasterKeyFrom(PGPKeyRing ring) {
+        Iterator<PGPPublicKey> it = ring.getPublicKeys();
+        while (it.hasNext()) {
+            PGPPublicKey k = it.next();
+            if (k.isMasterKey()) {
+                // There can only be one master key, so we can immediately return
+                return k;
+            }
+        }
+        return null;
+    }
+
     public static Set<Long> signingKeyIds(PGPSecretKeyRing ring) {
         Set<Long> ids = new HashSet<>();
         Iterator<PGPPublicKey> it = ring.getPublicKeys();
@@ -262,4 +279,54 @@ public class BCUtil {
     public static boolean keyRingContainsKeyWithId(PGPSecretKeyRing ring, long keyId) {
         return ring.getSecretKey(keyId) != null;
     }
+
+    /*
+    public static PGPKeyRing merge(PGPKeyRing one, PGPKeyRing other) {
+
+        PGPPublicKey masterOne = getMasterKeyFrom(one);
+        if (masterOne == null) {
+            throw new IllegalArgumentException("First KeyRing has no master key");
+        }
+
+        PGPPublicKey masterOther = getMasterKeyFrom(other);
+        if (masterOther == null) {
+            throw new IllegalArgumentException("Other KeyRing has no master key");
+        }
+
+        if (masterOne.getKeyID() != masterOther.getKeyID() ||
+                Arrays.equals(masterOne.getFingerprint(), masterOther.getFingerprint())) {
+            throw new IllegalArgumentException("Keys are not the same.");
+        }
+
+        PGPKeyRing merged = one;
+
+        boolean mergedIsSecret = (merged instanceof PGPSecretKeyRing);
+        boolean otherIsSecret = (other instanceof PGPSecretKeyRing);
+
+        for (Iterator it = other.getPublicKeys(); it.hasNext(); ) {
+
+            PGPPublicKey nextPublicKey = (PGPPublicKey) it.next();
+            PGPPublicKey pendant = merged.getPublicKey(nextPublicKey.getKeyID());
+
+            if (pendant == null) {
+                if (mergedIsSecret && otherIsSecret) {
+                    // Add secret key
+                    PGPSecretKey secretKey = ((PGPSecretKeyRing) other).getSecretKey(nextPublicKey.getKeyID());
+                    merged = PGPSecretKeyRing.insertSecretKey((PGPSecretKeyRing) merged, secretKey);
+                } else {
+                    if (mergedIsSecret) {
+                        PGPSecretKeyRing mergedAsSecret = (PGPSecretKeyRing) merged;
+                        PGPSecretKey secretKey = mergedAsSecret.getSecretKey(nextPublicKey.getKeyID());
+                        if (secretKey == null) {
+                            PGPPublicKeyRing mergedAsPublic = publicKeyRingFromSecretKeyRing((PGPSecretKeyRing) merged);
+                            mergedAsPublic = PGPPublicKeyRing.insertPublicKey(mergedAsPublic, nextPublicKey);
+                            mergedAsSecret = PGPSecretKeyRing.replacePublicKeys(mergedAsSecret, mergedAsPublic);
+                            merged = mergedAsSecret;
+                        }
+                    }
+                }
+            }
+        }
+    }
+    */
 }
diff --git a/src/test/java/org/pgpainless/pgpainless/EncryptDecryptTest.java b/src/test/java/org/pgpainless/pgpainless/EncryptDecryptTest.java
index cfdc4ea6..938e25af 100644
--- a/src/test/java/org/pgpainless/pgpainless/EncryptDecryptTest.java
+++ b/src/test/java/org/pgpainless/pgpainless/EncryptDecryptTest.java
@@ -43,8 +43,8 @@ import org.pgpainless.pgpainless.algorithm.SymmetricKeyAlgorithm;
 import org.pgpainless.pgpainless.decryption_verification.DecryptionStream;
 import org.pgpainless.pgpainless.decryption_verification.PainlessResult;
 import org.pgpainless.pgpainless.encryption_signing.EncryptionStream;
-import org.pgpainless.pgpainless.key.SecretKeyRingProtector;
-import org.pgpainless.pgpainless.key.UnprotectedKeysProtector;
+import org.pgpainless.pgpainless.key.protection.SecretKeyRingProtector;
+import org.pgpainless.pgpainless.key.protection.UnprotectedKeysProtector;
 import org.pgpainless.pgpainless.key.generation.KeySpec;
 import org.pgpainless.pgpainless.key.generation.type.ElGamal_GENERAL;
 import org.pgpainless.pgpainless.key.generation.type.RSA_GENERAL;
diff --git a/src/test/java/org/pgpainless/pgpainless/LengthTest.java b/src/test/java/org/pgpainless/pgpainless/LengthTest.java
index 8592c15c..9e4a2fde 100644
--- a/src/test/java/org/pgpainless/pgpainless/LengthTest.java
+++ b/src/test/java/org/pgpainless/pgpainless/LengthTest.java
@@ -31,8 +31,8 @@ import org.bouncycastle.openpgp.PGPPublicKeyRing;
 import org.bouncycastle.openpgp.PGPSecretKeyRing;
 import org.bouncycastle.util.io.Streams;
 import org.junit.Ignore;
-import org.pgpainless.pgpainless.key.SecretKeyRingProtector;
-import org.pgpainless.pgpainless.key.UnprotectedKeysProtector;
+import org.pgpainless.pgpainless.key.protection.SecretKeyRingProtector;
+import org.pgpainless.pgpainless.key.protection.UnprotectedKeysProtector;
 import org.pgpainless.pgpainless.key.generation.type.length.RsaLength;
 import org.pgpainless.pgpainless.util.BCUtil;
 
diff --git a/src/test/java/org/pgpainless/pgpainless/TestKeysTest.java b/src/test/java/org/pgpainless/pgpainless/TestKeysTest.java
index 809a3142..0abe4083 100644
--- a/src/test/java/org/pgpainless/pgpainless/TestKeysTest.java
+++ b/src/test/java/org/pgpainless/pgpainless/TestKeysTest.java
@@ -31,7 +31,7 @@ import org.bouncycastle.openpgp.PGPSecretKeyRingCollection;
 import org.bouncycastle.util.io.Streams;
 import org.junit.Test;
 import org.pgpainless.pgpainless.decryption_verification.DecryptionStream;
-import org.pgpainless.pgpainless.key.UnprotectedKeysProtector;
+import org.pgpainless.pgpainless.key.protection.UnprotectedKeysProtector;
 import org.pgpainless.pgpainless.util.BCUtil;
 
 public class TestKeysTest extends AbstractPGPainlessTest {