From 1bce378e6ddeeb3aa5842c1c1c41263aae09fe91 Mon Sep 17 00:00:00 2001
From: Florian Schmaus <flo@geekplace.eu>
Date: Mon, 5 Aug 2019 08:28:42 +0200
Subject: [PATCH] smack-omemo*: Do not swallow IOException deep within the
 library

Those exception are caused by I/O operations in the OmemoStore, which
is now declaring that it throws those (since it is not uncommon for
I/O operations to cause IOExceptions). After all, this is nicely
demonstrated as this change is caused by switching with this commit to
the Android API 19 compatible methods in FileBasedOmemoStore, which
throw.

The library can not decide what to do in case of those exceptions,
hence it is sensible to expose them to the user.
---
 .../AbstractTwoUsersOmemoIntegrationTest.java |   3 +-
 .../smackx/omemo/OmemoMamDecryptionTest.java  |   3 +-
 .../smackx/omemo/OmemoManagerSetupHelper.java |   7 +-
 .../omemo/ReadOnlyDeviceIntegrationTest.java  |   6 +-
 .../omemo/signal/SignalOmemoRatchet.java      |   3 +-
 .../signal/SignalOmemoStoreConnector.java     |  62 ++++-
 .../smackx/omemo/CachingOmemoStore.java       |  47 ++--
 .../smackx/omemo/FileBasedOmemoStore.java     | 232 +++---------------
 .../smackx/omemo/OmemoManager.java            |  71 ++++--
 .../smackx/omemo/OmemoRatchet.java            |   7 +-
 .../smackx/omemo/OmemoService.java            |  65 +++--
 .../jivesoftware/smackx/omemo/OmemoStore.java | 105 +++++---
 ...OmemoCarbonCopyStanzaReceivedListener.java |   5 +-
 .../OmemoMessageStanzaReceivedListener.java   |   4 +-
 .../omemo/util/OmemoMessageBuilder.java       |   4 +-
 .../smackx/omemo/OmemoStoreTest.java          |   6 +-
 16 files changed, 299 insertions(+), 331 deletions(-)

diff --git a/smack-integration-test/src/main/java/org/jivesoftware/smackx/omemo/AbstractTwoUsersOmemoIntegrationTest.java b/smack-integration-test/src/main/java/org/jivesoftware/smackx/omemo/AbstractTwoUsersOmemoIntegrationTest.java
index 4903fe72b..68cd5f30c 100644
--- a/smack-integration-test/src/main/java/org/jivesoftware/smackx/omemo/AbstractTwoUsersOmemoIntegrationTest.java
+++ b/smack-integration-test/src/main/java/org/jivesoftware/smackx/omemo/AbstractTwoUsersOmemoIntegrationTest.java
@@ -19,6 +19,7 @@ package org.jivesoftware.smackx.omemo;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 
+import java.io.IOException;
 import java.util.logging.Level;
 
 import org.jivesoftware.smack.SmackException;
@@ -64,7 +65,7 @@ public abstract class AbstractTwoUsersOmemoIntegrationTest extends AbstractOmemo
     }
 
     @AfterClass
-    public void cleanUp() {
+    public void cleanUp() throws IOException {
         alice.stopStanzaAndPEPListeners();
         bob.stopStanzaAndPEPListeners();
         OmemoManagerSetupHelper.cleanUpPubSub(alice);
diff --git a/smack-integration-test/src/main/java/org/jivesoftware/smackx/omemo/OmemoMamDecryptionTest.java b/smack-integration-test/src/main/java/org/jivesoftware/smackx/omemo/OmemoMamDecryptionTest.java
index 2c3017e74..b562db8f8 100644
--- a/smack-integration-test/src/main/java/org/jivesoftware/smackx/omemo/OmemoMamDecryptionTest.java
+++ b/smack-integration-test/src/main/java/org/jivesoftware/smackx/omemo/OmemoMamDecryptionTest.java
@@ -18,6 +18,7 @@ package org.jivesoftware.smackx.omemo;
 
 import static org.junit.Assert.assertEquals;
 
+import java.io.IOException;
 import java.util.List;
 
 import org.jivesoftware.smack.SmackException;
@@ -50,7 +51,7 @@ public class OmemoMamDecryptionTest extends AbstractTwoUsersOmemoIntegrationTest
     @SmackIntegrationTest
     public void mamDecryptionTest() throws XMPPException.XMPPErrorException, SmackException.NotLoggedInException,
             SmackException.NotConnectedException, InterruptedException, SmackException.NoResponseException,
-            CryptoFailedException, UndecidedOmemoIdentityException {
+            CryptoFailedException, UndecidedOmemoIdentityException, IOException {
         // Make sure, Bobs server stores messages in the archive
         MamManager bobsMamManager = MamManager.getInstanceFor(bob.getConnection());
         bobsMamManager.enableMamForAllMessages();
diff --git a/smack-integration-test/src/main/java/org/jivesoftware/smackx/omemo/OmemoManagerSetupHelper.java b/smack-integration-test/src/main/java/org/jivesoftware/smackx/omemo/OmemoManagerSetupHelper.java
index 83234924d..97fa93820 100644
--- a/smack-integration-test/src/main/java/org/jivesoftware/smackx/omemo/OmemoManagerSetupHelper.java
+++ b/smack-integration-test/src/main/java/org/jivesoftware/smackx/omemo/OmemoManagerSetupHelper.java
@@ -20,6 +20,7 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
+import java.io.IOException;
 import java.util.HashMap;
 
 import org.jivesoftware.smack.SmackException;
@@ -46,7 +47,7 @@ public class OmemoManagerSetupHelper {
     public static void trustAllIdentities(OmemoManager alice, OmemoManager bob)
             throws InterruptedException, SmackException.NotConnectedException, SmackException.NotLoggedInException,
             SmackException.NoResponseException, CannotEstablishOmemoSessionException, CorruptedOmemoKeyException,
-            XMPPException.XMPPErrorException, PubSubException.NotALeafNodeException {
+            XMPPException.XMPPErrorException, PubSubException.NotALeafNodeException, IOException {
         Roster roster = Roster.getInstanceFor(alice.getConnection());
 
         if (alice.getOwnJid() != bob.getOwnJid() &&
@@ -66,7 +67,7 @@ public class OmemoManagerSetupHelper {
     public static void trustAllIdentitiesWithTests(OmemoManager alice, OmemoManager bob)
             throws InterruptedException, SmackException.NotConnectedException, SmackException.NotLoggedInException,
             SmackException.NoResponseException, CannotEstablishOmemoSessionException, CorruptedOmemoKeyException,
-            XMPPException.XMPPErrorException, PubSubException.NotALeafNodeException {
+            XMPPException.XMPPErrorException, PubSubException.NotALeafNodeException, IOException {
         alice.requestDeviceListUpdateFor(bob.getOwnJid());
         HashMap<OmemoDevice, OmemoFingerprint> fps1 = alice.getActiveFingerprints(bob.getOwnJid());
 
@@ -124,7 +125,7 @@ public class OmemoManagerSetupHelper {
         }
     }
 
-    public static void cleanUpPubSub(OmemoManager omemoManager) {
+    public static void cleanUpPubSub(OmemoManager omemoManager) throws IOException {
         PubSubManager pm = PubSubManager.getInstanceFor(omemoManager.getConnection(), omemoManager.getOwnJid());
         try {
             omemoManager.requestDeviceListUpdateFor(omemoManager.getOwnJid());
diff --git a/smack-integration-test/src/main/java/org/jivesoftware/smackx/omemo/ReadOnlyDeviceIntegrationTest.java b/smack-integration-test/src/main/java/org/jivesoftware/smackx/omemo/ReadOnlyDeviceIntegrationTest.java
index 3164d6668..815d4a032 100644
--- a/smack-integration-test/src/main/java/org/jivesoftware/smackx/omemo/ReadOnlyDeviceIntegrationTest.java
+++ b/smack-integration-test/src/main/java/org/jivesoftware/smackx/omemo/ReadOnlyDeviceIntegrationTest.java
@@ -20,6 +20,8 @@ import static junit.framework.TestCase.assertEquals;
 import static junit.framework.TestCase.assertFalse;
 import static junit.framework.TestCase.assertTrue;
 
+import java.io.IOException;
+
 import org.jivesoftware.smack.SmackException;
 import org.jivesoftware.smack.XMPPException;
 import org.jivesoftware.smackx.omemo.exceptions.CryptoFailedException;
@@ -37,7 +39,9 @@ public class ReadOnlyDeviceIntegrationTest extends AbstractTwoUsersOmemoIntegrat
     }
 
     @SmackIntegrationTest
-    public void test() throws InterruptedException, SmackException.NoResponseException, SmackException.NotLoggedInException, SmackException.NotConnectedException, CryptoFailedException, UndecidedOmemoIdentityException {
+    public void test() throws InterruptedException, SmackException.NoResponseException,
+                    SmackException.NotLoggedInException, SmackException.NotConnectedException, CryptoFailedException,
+                    UndecidedOmemoIdentityException, IOException {
         boolean prevIgnoreReadOnlyConf = OmemoConfiguration.getIgnoreReadOnlyDevices();
         int prevMaxMessageCounter = OmemoConfiguration.getMaxReadOnlyMessageCount();
 
diff --git a/smack-omemo-signal/src/main/java/org/jivesoftware/smackx/omemo/signal/SignalOmemoRatchet.java b/smack-omemo-signal/src/main/java/org/jivesoftware/smackx/omemo/signal/SignalOmemoRatchet.java
index de20f69a9..c219b6f14 100644
--- a/smack-omemo-signal/src/main/java/org/jivesoftware/smackx/omemo/signal/SignalOmemoRatchet.java
+++ b/smack-omemo-signal/src/main/java/org/jivesoftware/smackx/omemo/signal/SignalOmemoRatchet.java
@@ -20,6 +20,7 @@
  */
 package org.jivesoftware.smackx.omemo.signal;
 
+import java.io.IOException;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
@@ -73,7 +74,7 @@ public class SignalOmemoRatchet
     @Override
     public byte[] doubleRatchetDecrypt(OmemoDevice sender, byte[] encryptedKey)
             throws CorruptedOmemoKeyException, NoRawSessionException, CryptoFailedException,
-            UntrustedOmemoIdentityException {
+            UntrustedOmemoIdentityException, IOException {
 
         SessionCipher cipher = getCipher(sender);
         byte[] decryptedKey;
diff --git a/smack-omemo-signal/src/main/java/org/jivesoftware/smackx/omemo/signal/SignalOmemoStoreConnector.java b/smack-omemo-signal/src/main/java/org/jivesoftware/smackx/omemo/signal/SignalOmemoStoreConnector.java
index 0f607603a..1aae64856 100644
--- a/smack-omemo-signal/src/main/java/org/jivesoftware/smackx/omemo/signal/SignalOmemoStoreConnector.java
+++ b/smack-omemo-signal/src/main/java/org/jivesoftware/smackx/omemo/signal/SignalOmemoStoreConnector.java
@@ -20,6 +20,7 @@
  */
 package org.jivesoftware.smackx.omemo.signal;
 
+import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.TreeMap;
@@ -79,7 +80,7 @@ public class SignalOmemoStoreConnector
     public IdentityKeyPair getIdentityKeyPair() {
         try {
             return omemoStore.loadOmemoIdentityKeyPair(getOurDevice());
-        } catch (CorruptedOmemoKeyException e) {
+        } catch (CorruptedOmemoKeyException | IOException e) {
             LOGGER.log(Level.SEVERE, "IdentityKeyPair seems to be invalid.", e);
             return null;
         }
@@ -103,7 +104,11 @@ public class SignalOmemoStoreConnector
             throw new AssertionError(e);
         }
 
-        omemoStore.storeOmemoIdentityKey(getOurDevice(), device, identityKey);
+        try {
+            omemoStore.storeOmemoIdentityKey(getOurDevice(), device, identityKey);
+        } catch (IOException e) {
+            throw new IllegalStateException(e);
+        }
         return true;
     }
 
@@ -118,7 +123,12 @@ public class SignalOmemoStoreConnector
 
     @Override
     public PreKeyRecord loadPreKey(int i) throws InvalidKeyIdException {
-        PreKeyRecord preKey = omemoStore.loadOmemoPreKey(getOurDevice(), i);
+        PreKeyRecord preKey;
+        try {
+            preKey = omemoStore.loadOmemoPreKey(getOurDevice(), i);
+        } catch (IOException e) {
+            throw new IllegalStateException(e);
+        }
 
         if (preKey == null) {
             throw new InvalidKeyIdException("No PreKey with Id " + i + " found.");
@@ -129,7 +139,11 @@ public class SignalOmemoStoreConnector
 
     @Override
     public void storePreKey(int i, PreKeyRecord preKeyRecord) {
-        omemoStore.storeOmemoPreKey(getOurDevice(), i, preKeyRecord);
+        try {
+            omemoStore.storeOmemoPreKey(getOurDevice(), i, preKeyRecord);
+        } catch (IOException e) {
+            throw new IllegalStateException(e);
+        }
     }
 
     @Override
@@ -155,7 +169,12 @@ public class SignalOmemoStoreConnector
             throw new AssertionError(e);
         }
 
-        SessionRecord record = omemoStore.loadRawSession(getOurDevice(), device);
+        SessionRecord record;
+        try {
+            record = omemoStore.loadRawSession(getOurDevice(), device);
+        } catch (IOException e) {
+            throw new IllegalStateException(e);
+        }
 
         if (record != null) {
             return record;
@@ -173,7 +192,11 @@ public class SignalOmemoStoreConnector
             throw new AssertionError(e);
         }
 
-        return new ArrayList<>(omemoStore.loadAllRawSessionsOf(getOurDevice(), jid).keySet());
+        try {
+            return new ArrayList<>(omemoStore.loadAllRawSessionsOf(getOurDevice(), jid).keySet());
+        } catch (IOException e) {
+            throw new IllegalStateException(e);
+        }
     }
 
     @Override
@@ -185,7 +208,11 @@ public class SignalOmemoStoreConnector
             throw new AssertionError(e);
         }
 
-        omemoStore.storeRawSession(getOurDevice(), device, sessionRecord);
+        try {
+            omemoStore.storeRawSession(getOurDevice(), device, sessionRecord);
+        } catch (IOException e) {
+            throw new IllegalStateException(e);
+        }
     }
 
     @Override
@@ -226,7 +253,12 @@ public class SignalOmemoStoreConnector
 
     @Override
     public SignedPreKeyRecord loadSignedPreKey(int i) throws InvalidKeyIdException {
-        SignedPreKeyRecord signedPreKeyRecord = omemoStore.loadOmemoSignedPreKey(getOurDevice(), i);
+        SignedPreKeyRecord signedPreKeyRecord;
+        try {
+            signedPreKeyRecord = omemoStore.loadOmemoSignedPreKey(getOurDevice(), i);
+        } catch (IOException e) {
+            throw new IllegalStateException(e);
+        }
         if (signedPreKeyRecord == null) {
             throw new InvalidKeyIdException("No signed preKey with id " + i + " found.");
         }
@@ -236,14 +268,22 @@ public class SignalOmemoStoreConnector
     @Override
     public List<SignedPreKeyRecord> loadSignedPreKeys() {
 
-        TreeMap<Integer, SignedPreKeyRecord> signedPreKeyRecordHashMap =
-                omemoStore.loadOmemoSignedPreKeys(getOurDevice());
+        TreeMap<Integer, SignedPreKeyRecord> signedPreKeyRecordHashMap;
+        try {
+            signedPreKeyRecordHashMap = omemoStore.loadOmemoSignedPreKeys(getOurDevice());
+        } catch (IOException e) {
+            throw new IllegalStateException(e);
+        }
         return new ArrayList<>(signedPreKeyRecordHashMap.values());
     }
 
     @Override
     public void storeSignedPreKey(int i, SignedPreKeyRecord signedPreKeyRecord) {
-        omemoStore.storeOmemoSignedPreKey(getOurDevice(), i, signedPreKeyRecord);
+        try {
+            omemoStore.storeOmemoSignedPreKey(getOurDevice(), i, signedPreKeyRecord);
+        } catch (IOException e) {
+            throw new IllegalStateException(e);
+        }
     }
 
     @Override
diff --git a/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/CachingOmemoStore.java b/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/CachingOmemoStore.java
index 7ab0bcde6..d83984e6c 100644
--- a/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/CachingOmemoStore.java
+++ b/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/CachingOmemoStore.java
@@ -16,6 +16,7 @@
  */
 package org.jivesoftware.smackx.omemo;
 
+import java.io.IOException;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.SortedSet;
@@ -80,7 +81,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
 
     @Override
     public T_IdKeyPair loadOmemoIdentityKeyPair(OmemoDevice userDevice)
-            throws CorruptedOmemoKeyException {
+            throws CorruptedOmemoKeyException, IOException {
         T_IdKeyPair pair = getCache(userDevice).identityKeyPair;
 
         if (pair == null && persistent != null) {
@@ -94,7 +95,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
     }
 
     @Override
-    public void storeOmemoIdentityKeyPair(OmemoDevice userDevice, T_IdKeyPair identityKeyPair) {
+    public void storeOmemoIdentityKeyPair(OmemoDevice userDevice, T_IdKeyPair identityKeyPair) throws IOException {
         getCache(userDevice).identityKeyPair = identityKeyPair;
         if (persistent != null) {
             persistent.storeOmemoIdentityKeyPair(userDevice, identityKeyPair);
@@ -111,7 +112,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
 
     @Override
     public T_IdKey loadOmemoIdentityKey(OmemoDevice userDevice, OmemoDevice contactsDevice)
-            throws CorruptedOmemoKeyException {
+            throws CorruptedOmemoKeyException, IOException {
         T_IdKey idKey = getCache(userDevice).identityKeys.get(contactsDevice);
 
         if (idKey == null && persistent != null) {
@@ -125,7 +126,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
     }
 
     @Override
-    public void storeOmemoIdentityKey(OmemoDevice userDevice, OmemoDevice device, T_IdKey t_idKey) {
+    public void storeOmemoIdentityKey(OmemoDevice userDevice, OmemoDevice device, T_IdKey t_idKey) throws IOException {
         getCache(userDevice).identityKeys.put(device, t_idKey);
         if (persistent != null) {
             persistent.storeOmemoIdentityKey(userDevice, device, t_idKey);
@@ -141,7 +142,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
     }
 
     @Override
-    public void storeOmemoMessageCounter(OmemoDevice userDevice, OmemoDevice contactsDevice, int counter) {
+    public void storeOmemoMessageCounter(OmemoDevice userDevice, OmemoDevice contactsDevice, int counter) throws IOException {
         getCache(userDevice).messageCounters.put(contactsDevice, counter);
         if (persistent != null) {
             persistent.storeOmemoMessageCounter(userDevice, contactsDevice, counter);
@@ -149,7 +150,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
     }
 
     @Override
-    public int loadOmemoMessageCounter(OmemoDevice userDevice, OmemoDevice contactsDevice) {
+    public int loadOmemoMessageCounter(OmemoDevice userDevice, OmemoDevice contactsDevice) throws IOException {
         Integer counter = getCache(userDevice).messageCounters.get(contactsDevice);
         if (counter == null && persistent != null) {
             counter = persistent.loadOmemoMessageCounter(userDevice, contactsDevice);
@@ -165,7 +166,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
     }
 
     @Override
-    public void setDateOfLastReceivedMessage(OmemoDevice userDevice, OmemoDevice from, Date date) {
+    public void setDateOfLastReceivedMessage(OmemoDevice userDevice, OmemoDevice from, Date date) throws IOException {
         getCache(userDevice).lastMessagesDates.put(from, date);
         if (persistent != null) {
             persistent.setDateOfLastReceivedMessage(userDevice, from, date);
@@ -173,7 +174,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
     }
 
     @Override
-    public Date getDateOfLastReceivedMessage(OmemoDevice userDevice, OmemoDevice from) {
+    public Date getDateOfLastReceivedMessage(OmemoDevice userDevice, OmemoDevice from) throws IOException {
         Date last = getCache(userDevice).lastMessagesDates.get(from);
 
         if (last == null && persistent != null) {
@@ -187,7 +188,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
     }
 
     @Override
-    public void setDateOfLastDeviceIdPublication(OmemoDevice userDevice, OmemoDevice contactsDevice, Date date) {
+    public void setDateOfLastDeviceIdPublication(OmemoDevice userDevice, OmemoDevice contactsDevice, Date date) throws IOException {
         getCache(userDevice).lastDeviceIdPublicationDates.put(contactsDevice, date);
         if (persistent != null) {
             persistent.setDateOfLastReceivedMessage(userDevice, contactsDevice, date);
@@ -195,7 +196,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
     }
 
     @Override
-    public Date getDateOfLastDeviceIdPublication(OmemoDevice userDevice, OmemoDevice contactsDevice) {
+    public Date getDateOfLastDeviceIdPublication(OmemoDevice userDevice, OmemoDevice contactsDevice) throws IOException {
         Date last = getCache(userDevice).lastDeviceIdPublicationDates.get(contactsDevice);
 
         if (last == null && persistent != null) {
@@ -209,7 +210,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
     }
 
     @Override
-    public void setDateOfLastSignedPreKeyRenewal(OmemoDevice userDevice, Date date) {
+    public void setDateOfLastSignedPreKeyRenewal(OmemoDevice userDevice, Date date) throws IOException {
         getCache(userDevice).lastRenewalDate = date;
         if (persistent != null) {
             persistent.setDateOfLastSignedPreKeyRenewal(userDevice, date);
@@ -217,7 +218,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
     }
 
     @Override
-    public Date getDateOfLastSignedPreKeyRenewal(OmemoDevice userDevice) {
+    public Date getDateOfLastSignedPreKeyRenewal(OmemoDevice userDevice) throws IOException {
         Date lastRenewal = getCache(userDevice).lastRenewalDate;
 
         if (lastRenewal == null && persistent != null) {
@@ -231,7 +232,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
     }
 
     @Override
-    public T_PreKey loadOmemoPreKey(OmemoDevice userDevice, int preKeyId) {
+    public T_PreKey loadOmemoPreKey(OmemoDevice userDevice, int preKeyId) throws IOException {
         T_PreKey preKey = getCache(userDevice).preKeys.get(preKeyId);
 
         if (preKey == null && persistent != null) {
@@ -245,7 +246,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
     }
 
     @Override
-    public void storeOmemoPreKey(OmemoDevice userDevice, int preKeyId, T_PreKey t_preKey) {
+    public void storeOmemoPreKey(OmemoDevice userDevice, int preKeyId, T_PreKey t_preKey) throws IOException {
         getCache(userDevice).preKeys.put(preKeyId, t_preKey);
         if (persistent != null) {
             persistent.storeOmemoPreKey(userDevice, preKeyId, t_preKey);
@@ -261,7 +262,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
     }
 
     @Override
-    public TreeMap<Integer, T_PreKey> loadOmemoPreKeys(OmemoDevice userDevice) {
+    public TreeMap<Integer, T_PreKey> loadOmemoPreKeys(OmemoDevice userDevice) throws IOException {
         TreeMap<Integer, T_PreKey> preKeys = getCache(userDevice).preKeys;
 
         if (preKeys.isEmpty() && persistent != null) {
@@ -272,7 +273,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
     }
 
     @Override
-    public T_SigPreKey loadOmemoSignedPreKey(OmemoDevice userDevice, int signedPreKeyId) {
+    public T_SigPreKey loadOmemoSignedPreKey(OmemoDevice userDevice, int signedPreKeyId) throws IOException {
         T_SigPreKey sigPreKey = getCache(userDevice).signedPreKeys.get(signedPreKeyId);
 
         if (sigPreKey == null && persistent != null) {
@@ -286,7 +287,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
     }
 
     @Override
-    public TreeMap<Integer, T_SigPreKey> loadOmemoSignedPreKeys(OmemoDevice userDevice) {
+    public TreeMap<Integer, T_SigPreKey> loadOmemoSignedPreKeys(OmemoDevice userDevice) throws IOException {
         TreeMap<Integer, T_SigPreKey> sigPreKeys = getCache(userDevice).signedPreKeys;
 
         if (sigPreKeys.isEmpty() && persistent != null) {
@@ -299,7 +300,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
     @Override
     public void storeOmemoSignedPreKey(OmemoDevice userDevice,
                                        int signedPreKeyId,
-                                       T_SigPreKey signedPreKey) {
+                                       T_SigPreKey signedPreKey) throws IOException {
         getCache(userDevice).signedPreKeys.put(signedPreKeyId, signedPreKey);
         if (persistent != null) {
             persistent.storeOmemoSignedPreKey(userDevice, signedPreKeyId, signedPreKey);
@@ -315,7 +316,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
     }
 
     @Override
-    public T_Sess loadRawSession(OmemoDevice userDevice, OmemoDevice contactsDevice) {
+    public T_Sess loadRawSession(OmemoDevice userDevice, OmemoDevice contactsDevice) throws IOException {
         HashMap<Integer, T_Sess> contactSessions = getCache(userDevice).sessions.get(contactsDevice.getJid());
         if (contactSessions == null) {
             contactSessions = new HashMap<>();
@@ -334,7 +335,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
     }
 
     @Override
-    public HashMap<Integer, T_Sess> loadAllRawSessionsOf(OmemoDevice userDevice, BareJid contact) {
+    public HashMap<Integer, T_Sess> loadAllRawSessionsOf(OmemoDevice userDevice, BareJid contact) throws IOException {
         HashMap<Integer, T_Sess> sessions = getCache(userDevice).sessions.get(contact);
         if (sessions == null) {
             sessions = new HashMap<>();
@@ -349,7 +350,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
     }
 
     @Override
-    public void storeRawSession(OmemoDevice userDevice, OmemoDevice contactsDevicece, T_Sess session) {
+    public void storeRawSession(OmemoDevice userDevice, OmemoDevice contactsDevicece, T_Sess session) throws IOException {
         HashMap<Integer, T_Sess> sessions = getCache(userDevice).sessions.get(contactsDevicece.getJid());
         if (sessions == null) {
             sessions = new HashMap<>();
@@ -391,7 +392,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
     }
 
     @Override
-    public OmemoCachedDeviceList loadCachedDeviceList(OmemoDevice userDevice, BareJid contact) {
+    public OmemoCachedDeviceList loadCachedDeviceList(OmemoDevice userDevice, BareJid contact) throws IOException {
         OmemoCachedDeviceList list = getCache(userDevice).deviceLists.get(contact);
 
         if (list == null && persistent != null) {
@@ -407,7 +408,7 @@ public class CachingOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Se
     @Override
     public void storeCachedDeviceList(OmemoDevice userDevice,
                                       BareJid contact,
-                                      OmemoCachedDeviceList deviceList) {
+                                      OmemoCachedDeviceList deviceList) throws IOException {
         getCache(userDevice).deviceLists.put(contact, new OmemoCachedDeviceList(deviceList));
 
         if (persistent != null) {
diff --git a/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/FileBasedOmemoStore.java b/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/FileBasedOmemoStore.java
index 6cfba87a8..612e955ff 100644
--- a/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/FileBasedOmemoStore.java
+++ b/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/FileBasedOmemoStore.java
@@ -1,6 +1,6 @@
 /**
  *
- * Copyright 2017 Paul Schaub
+ * Copyright 2017 Paul Schaub, 2019 Florian Schmaus.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,7 +21,6 @@ import java.io.DataOutputStream;
 import java.io.EOFException;
 import java.io.File;
 import java.io.FileInputStream;
-import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.util.Collections;
@@ -36,7 +35,6 @@ import java.util.TreeSet;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
-import org.jivesoftware.smack.util.CloseableUtil;
 import org.jivesoftware.smack.util.stringencoder.BareJidEncoder;
 
 import org.jivesoftware.smackx.omemo.exceptions.CorruptedOmemoKeyException;
@@ -67,13 +65,13 @@ public abstract class FileBasedOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigP
 
     @Override
     public T_IdKeyPair loadOmemoIdentityKeyPair(OmemoDevice userDevice)
-            throws CorruptedOmemoKeyException {
+            throws CorruptedOmemoKeyException, IOException {
         File identityKeyPairPath = hierarchy.getIdentityKeyPairPath(userDevice);
         return keyUtil().identityKeyPairFromBytes(readBytes(identityKeyPairPath));
     }
 
     @Override
-    public void storeOmemoIdentityKeyPair(OmemoDevice userDevice, T_IdKeyPair identityKeyPair) {
+    public void storeOmemoIdentityKeyPair(OmemoDevice userDevice, T_IdKeyPair identityKeyPair) throws IOException {
         File identityKeyPairPath = hierarchy.getIdentityKeyPairPath(userDevice);
         writeBytes(identityKeyPairPath, keyUtil().identityKeyPairToBytes(identityKeyPair));
     }
@@ -88,14 +86,14 @@ public abstract class FileBasedOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigP
 
     @Override
     public T_IdKey loadOmemoIdentityKey(OmemoDevice userDevice, OmemoDevice contactsDevice)
-            throws CorruptedOmemoKeyException {
+            throws CorruptedOmemoKeyException, IOException {
         File identityKeyPath = hierarchy.getContactsIdentityKeyPath(userDevice, contactsDevice);
         byte[] bytes = readBytes(identityKeyPath);
         return bytes != null ? keyUtil().identityKeyFromBytes(bytes) : null;
     }
 
     @Override
-    public void storeOmemoIdentityKey(OmemoDevice userDevice, OmemoDevice contactsDevice, T_IdKey t_idKey) {
+    public void storeOmemoIdentityKey(OmemoDevice userDevice, OmemoDevice contactsDevice, T_IdKey t_idKey) throws IOException {
         File identityKeyPath = hierarchy.getContactsIdentityKeyPath(userDevice, contactsDevice);
         writeBytes(identityKeyPath, keyUtil().identityKeyToBytes(t_idKey));
     }
@@ -126,46 +124,46 @@ public abstract class FileBasedOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigP
     }
 
     @Override
-    public void setDateOfLastReceivedMessage(OmemoDevice userDevice, OmemoDevice contactsDevice, Date date) {
+    public void setDateOfLastReceivedMessage(OmemoDevice userDevice, OmemoDevice contactsDevice, Date date) throws IOException {
         File lastMessageReceived = hierarchy.getLastMessageReceivedDatePath(userDevice, contactsDevice);
         writeLong(lastMessageReceived, date.getTime());
     }
 
     @Override
-    public Date getDateOfLastReceivedMessage(OmemoDevice userDevice, OmemoDevice contactsDevice) {
+    public Date getDateOfLastReceivedMessage(OmemoDevice userDevice, OmemoDevice contactsDevice) throws IOException {
         File lastMessageReceived = hierarchy.getLastMessageReceivedDatePath(userDevice, contactsDevice);
         Long date = readLong(lastMessageReceived);
         return date != null ? new Date(date) : null;
     }
 
     @Override
-    public void setDateOfLastDeviceIdPublication(OmemoDevice userDevice, OmemoDevice contactsDevice, Date date) {
+    public void setDateOfLastDeviceIdPublication(OmemoDevice userDevice, OmemoDevice contactsDevice, Date date) throws IOException {
         File lastDeviceIdPublished = hierarchy.getLastDeviceIdPublicationDatePath(userDevice, contactsDevice);
         writeLong(lastDeviceIdPublished, date.getTime());
     }
 
     @Override
-    public Date getDateOfLastDeviceIdPublication(OmemoDevice userDevice, OmemoDevice contactsDevice) {
+    public Date getDateOfLastDeviceIdPublication(OmemoDevice userDevice, OmemoDevice contactsDevice) throws IOException {
         File lastDeviceIdPublished = hierarchy.getLastDeviceIdPublicationDatePath(userDevice, contactsDevice);
         Long date = readLong(lastDeviceIdPublished);
         return date != null ? new Date(date) : null;
     }
 
     @Override
-    public void setDateOfLastSignedPreKeyRenewal(OmemoDevice userDevice, Date date) {
+    public void setDateOfLastSignedPreKeyRenewal(OmemoDevice userDevice, Date date) throws IOException {
         File lastSignedPreKeyRenewal = hierarchy.getLastSignedPreKeyRenewal(userDevice);
         writeLong(lastSignedPreKeyRenewal, date.getTime());
     }
 
     @Override
-    public Date getDateOfLastSignedPreKeyRenewal(OmemoDevice userDevice) {
+    public Date getDateOfLastSignedPreKeyRenewal(OmemoDevice userDevice) throws IOException {
         File lastSignedPreKeyRenewal = hierarchy.getLastSignedPreKeyRenewal(userDevice);
         Long date = readLong(lastSignedPreKeyRenewal);
         return date != null ? new Date(date) : null;
     }
 
     @Override
-    public T_PreKey loadOmemoPreKey(OmemoDevice userDevice, int preKeyId) {
+    public T_PreKey loadOmemoPreKey(OmemoDevice userDevice, int preKeyId) throws IOException {
         File preKeyPath = hierarchy.getPreKeyPath(userDevice, preKeyId);
         byte[] bytes = readBytes(preKeyPath);
 
@@ -181,7 +179,7 @@ public abstract class FileBasedOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigP
     }
 
     @Override
-    public void storeOmemoPreKey(OmemoDevice userDevice, int preKeyId, T_PreKey t_preKey) {
+    public void storeOmemoPreKey(OmemoDevice userDevice, int preKeyId, T_PreKey t_preKey) throws IOException {
         File preKeyPath = hierarchy.getPreKeyPath(userDevice, preKeyId);
         writeBytes(preKeyPath, keyUtil().preKeyToBytes(t_preKey));
     }
@@ -195,7 +193,7 @@ public abstract class FileBasedOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigP
     }
 
     @Override
-    public TreeMap<Integer, T_PreKey> loadOmemoPreKeys(OmemoDevice userDevice) {
+    public TreeMap<Integer, T_PreKey> loadOmemoPreKeys(OmemoDevice userDevice) throws IOException {
         File preKeyDirectory = hierarchy.getPreKeysDirectory(userDevice);
         TreeMap<Integer, T_PreKey> preKeys = new TreeMap<>();
 
@@ -221,7 +219,7 @@ public abstract class FileBasedOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigP
     }
 
     @Override
-    public T_SigPreKey loadOmemoSignedPreKey(OmemoDevice userDevice, int signedPreKeyId) {
+    public T_SigPreKey loadOmemoSignedPreKey(OmemoDevice userDevice, int signedPreKeyId) throws IOException {
         File signedPreKeyPath = new File(hierarchy.getSignedPreKeysDirectory(userDevice), Integer.toString(signedPreKeyId));
         byte[] bytes = readBytes(signedPreKeyPath);
         if (bytes != null) {
@@ -235,7 +233,7 @@ public abstract class FileBasedOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigP
     }
 
     @Override
-    public TreeMap<Integer, T_SigPreKey> loadOmemoSignedPreKeys(OmemoDevice userDevice) {
+    public TreeMap<Integer, T_SigPreKey> loadOmemoSignedPreKeys(OmemoDevice userDevice) throws IOException {
         File signedPreKeysDirectory = hierarchy.getSignedPreKeysDirectory(userDevice);
         TreeMap<Integer, T_SigPreKey> signedPreKeys = new TreeMap<>();
 
@@ -263,7 +261,7 @@ public abstract class FileBasedOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigP
     @Override
     public void storeOmemoSignedPreKey(OmemoDevice userDevice,
                                        int signedPreKeyId,
-                                       T_SigPreKey signedPreKey) {
+                                       T_SigPreKey signedPreKey) throws IOException {
         File signedPreKeyPath = new File(hierarchy.getSignedPreKeysDirectory(userDevice), Integer.toString(signedPreKeyId));
         writeBytes(signedPreKeyPath, keyUtil().signedPreKeyToBytes(signedPreKey));
     }
@@ -277,7 +275,7 @@ public abstract class FileBasedOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigP
     }
 
     @Override
-    public T_Sess loadRawSession(OmemoDevice userDevice, OmemoDevice contactsDevice) {
+    public T_Sess loadRawSession(OmemoDevice userDevice, OmemoDevice contactsDevice) throws IOException {
         File sessionPath = hierarchy.getContactsSessionPath(userDevice, contactsDevice);
         byte[] bytes = readBytes(sessionPath);
         if (bytes != null) {
@@ -291,7 +289,7 @@ public abstract class FileBasedOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigP
     }
 
     @Override
-    public HashMap<Integer, T_Sess> loadAllRawSessionsOf(OmemoDevice userDevice, BareJid contact) {
+    public HashMap<Integer, T_Sess> loadAllRawSessionsOf(OmemoDevice userDevice, BareJid contact) throws IOException {
         File contactsDirectory = hierarchy.getContactsDir(userDevice, contact);
         HashMap<Integer, T_Sess> sessions = new HashMap<>();
         String[] devices = contactsDirectory.list();
@@ -322,7 +320,7 @@ public abstract class FileBasedOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigP
     }
 
     @Override
-    public void storeRawSession(OmemoDevice userDevice, OmemoDevice contactsDevice, T_Sess session) {
+    public void storeRawSession(OmemoDevice userDevice, OmemoDevice contactsDevice, T_Sess session) throws IOException {
         File sessionPath = hierarchy.getContactsSessionPath(userDevice, contactsDevice);
         writeBytes(sessionPath, keyUtil().rawSessionToBytes(session));
     }
@@ -357,13 +355,13 @@ public abstract class FileBasedOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigP
     }
 
     @Override
-    public void storeOmemoMessageCounter(OmemoDevice userDevice, OmemoDevice contactsDevice, int counter) {
+    public void storeOmemoMessageCounter(OmemoDevice userDevice, OmemoDevice contactsDevice, int counter) throws IOException {
         File messageCounterFile = hierarchy.getDevicesMessageCounterPath(userDevice, contactsDevice);
         writeIntegers(messageCounterFile, Collections.singleton(counter));
     }
 
     @Override
-    public int loadOmemoMessageCounter(OmemoDevice userDevice, OmemoDevice contactsDevice) {
+    public int loadOmemoMessageCounter(OmemoDevice userDevice, OmemoDevice contactsDevice) throws IOException {
         File messageCounterFile = hierarchy.getDevicesMessageCounterPath(userDevice, contactsDevice);
         Set<Integer> integers = readIntegers(messageCounterFile);
 
@@ -375,7 +373,7 @@ public abstract class FileBasedOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigP
     }
 
     @Override
-    public OmemoCachedDeviceList loadCachedDeviceList(OmemoDevice userDevice, BareJid contact) {
+    public OmemoCachedDeviceList loadCachedDeviceList(OmemoDevice userDevice, BareJid contact) throws IOException {
         OmemoCachedDeviceList cachedDeviceList = new OmemoCachedDeviceList();
 
         if (contact == null) {
@@ -402,7 +400,7 @@ public abstract class FileBasedOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigP
     @Override
     public void storeCachedDeviceList(OmemoDevice userDevice,
                                       BareJid contact,
-                                      OmemoCachedDeviceList contactsDeviceList) {
+                                      OmemoCachedDeviceList contactsDeviceList) throws IOException {
         if (contact == null) {
             return;
         }
@@ -420,166 +418,7 @@ public abstract class FileBasedOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigP
         deleteDirectory(deviceDirectory);
     }
 
-    private static void writeLong(File target, long i) {
-        if (target == null) {
-            LOGGER.log(Level.WARNING, "Could not write long to null-path.");
-            return;
-        }
-
-        try {
-            FileHierarchy.createFile(target);
-        } catch (IOException e) {
-            LOGGER.log(Level.SEVERE, "Could not create file.", e);
-            return;
-        }
-
-        DataOutputStream out = null;
-        try {
-            out = new DataOutputStream(new FileOutputStream(target));
-            out.writeLong(i);
-
-        } catch (IOException e) {
-            LOGGER.log(Level.SEVERE, "Could not write longs to file.", e);
-        } finally {
-            CloseableUtil.maybeClose(out, LOGGER);
-        }
-    }
-
-    private static Long readLong(File target) {
-        if (target == null) {
-            LOGGER.log(Level.WARNING, "Could not read long from null-path.");
-            return null;
-        }
-
-        Long l;
-        DataInputStream in = null;
-
-        try {
-            in = new DataInputStream(new FileInputStream(target));
-            l = in.readLong();
-        } catch (FileNotFoundException e) {
-            l = null;
-        } catch (IOException e) {
-            LOGGER.log(Level.SEVERE, "Could not read long from file.", e);
-            return null;
-        } finally {
-            CloseableUtil.maybeClose(in, LOGGER);
-        }
-
-        return l;
-    }
-
-    private static void writeBytes(File target, byte[] bytes) {
-        if (target == null) {
-            LOGGER.log(Level.WARNING, "Could not write bytes to null-path.");
-            return;
-        }
-
-        // Create file
-        try {
-            FileHierarchy.createFile(target);
-        } catch (IOException e) {
-            LOGGER.log(Level.SEVERE, "Could not create file.", e);
-            return;
-        }
-
-        DataOutputStream out = null;
-
-        try {
-            out = new DataOutputStream(new FileOutputStream(target));
-            out.write(bytes);
-
-        } catch (IOException e) {
-            LOGGER.log(Level.SEVERE, "Could not write bytes to file.", e);
-        } finally {
-            CloseableUtil.maybeClose(out, LOGGER);
-        }
-    }
-
-    private static byte[] readBytes(File target) {
-        if (target == null) {
-            LOGGER.log(Level.WARNING, "Could not read bytes from null-path.");
-            return null;
-        }
-
-        byte[] b = null;
-        DataInputStream in = null;
-
-        try {
-            in = new DataInputStream(new FileInputStream(target));
-            b = new byte[(int) target.length()];
-            in.read(b);
-        } catch (FileNotFoundException e) {
-            b = null;
-        } catch (IOException e) {
-            LOGGER.log(Level.SEVERE, "Could not read bytes from file.", e);
-        } finally {
-            CloseableUtil.maybeClose(in, LOGGER);
-        }
-
-        return b;
-    }
-
-    private static void writeIntegers(File target, Set<Integer> integers) {
-        if (target == null) {
-            LOGGER.log(Level.WARNING, "Could not write integers to null-path.");
-            return;
-        }
-
-        DataOutputStream out = null;
-
-        try {
-            out = new DataOutputStream(new FileOutputStream(target));
-            for (int i : integers) {
-                out.writeInt(i);
-            }
-
-        } catch (IOException e) {
-            LOGGER.log(Level.SEVERE, "Could not write integers to file.", e);
-        } finally {
-            CloseableUtil.maybeClose(out, LOGGER);
-        }
-    }
-
-    private static Set<Integer> readIntegers(File target) {
-        if (target == null) {
-            LOGGER.log(Level.WARNING, "Could not read integers from null-path.");
-            return null;
-        }
-
-        HashSet<Integer> integers = new HashSet<>();
-        DataInputStream in = null;
-
-        try {
-            in = new DataInputStream(new FileInputStream(target));
-
-            try {
-                while (true) {
-                    integers.add(in.readInt());
-                }
-            } catch (EOFException e) {
-                // Reached end of the list.
-            }
-
-        } catch (FileNotFoundException e) {
-            integers = null;
-        } catch (IOException e) {
-            LOGGER.log(Level.SEVERE, "Could not read integers.", e);
-        } finally {
-            CloseableUtil.maybeClose(in, LOGGER);
-        }
-
-        return integers;
-    }
-
-    /**
-     * One day... *sheds a tear*
-     * TODO Use methods below once Smack's minimum Android API level is 19 or higher
-     */
-    /*
-    private static void writeLong(File target, long i)
-            throws IOException
-    {
+    private static void writeLong(File target, long i) throws IOException {
         if (target == null) {
             throw new IOException("Could not write long to null-path.");
         }
@@ -591,9 +430,7 @@ public abstract class FileBasedOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigP
         }
     }
 
-    private static Long readLong(File target)
-            throws IOException
-    {
+    private static Long readLong(File target) throws IOException {
         if (target == null) {
             throw new IOException("Could not read long from null-path.");
         }
@@ -607,9 +444,7 @@ public abstract class FileBasedOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigP
         }
     }
 
-    private static void writeBytes(File target, byte[] bytes)
-            throws IOException
-    {
+    private static void writeBytes(File target, byte[] bytes) throws IOException {
         if (target == null) {
             throw new IOException("Could not write bytes to null-path.");
         }
@@ -622,9 +457,7 @@ public abstract class FileBasedOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigP
         }
     }
 
-    private static byte[] readBytes(File target)
-            throws IOException
-    {
+    private static byte[] readBytes(File target) throws IOException {
         if (target == null) {
             throw new IOException("Could not read bytes from null-path.");
         }
@@ -641,9 +474,7 @@ public abstract class FileBasedOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigP
         return b;
     }
 
-    private static void writeIntegers(File target, Set<Integer> integers)
-            throws IOException
-    {
+    private static void writeIntegers(File target, Set<Integer> integers) throws IOException {
         if (target == null) {
             throw new IOException("Could not write integers to null-path.");
         }
@@ -657,9 +488,7 @@ public abstract class FileBasedOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigP
         }
     }
 
-    private static Set<Integer> readIntegers(File target)
-            throws IOException
-    {
+    private static Set<Integer> readIntegers(File target) throws IOException {
         if (target == null) {
             throw new IOException("Could not write integers to null-path.");
         }
@@ -682,7 +511,6 @@ public abstract class FileBasedOmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigP
 
         return integers;
     }
-     */
 
     /**
      * Delete a directory with all subdirectories.
diff --git a/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/OmemoManager.java b/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/OmemoManager.java
index 383dc3570..5b1807a8d 100644
--- a/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/OmemoManager.java
+++ b/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/OmemoManager.java
@@ -19,6 +19,7 @@ package org.jivesoftware.smackx.omemo;
 import static org.jivesoftware.smackx.omemo.util.OmemoConstants.OMEMO_NAMESPACE_V_AXOLOTL;
 import static org.jivesoftware.smackx.omemo.util.OmemoConstants.PEP_NODE_DEVICE_LIST_NOTIFY;
 
+import java.io.IOException;
 import java.security.NoSuchAlgorithmException;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -234,11 +235,12 @@ public final class OmemoManager extends Manager {
      * @throws XMPPException.XMPPErrorException
      * @throws SmackException.NotLoggedInException
      * @throws PubSubException.NotALeafNodeException
+     * @throws IOException
      */
     public void initialize()
             throws SmackException.NotLoggedInException, CorruptedOmemoKeyException, InterruptedException,
             SmackException.NoResponseException, SmackException.NotConnectedException, XMPPException.XMPPErrorException,
-            PubSubException.NotALeafNodeException {
+            PubSubException.NotALeafNodeException, IOException {
         synchronized (LOCK) {
             if (!connection().isAuthenticated()) {
                 throw new SmackException.NotLoggedInException();
@@ -279,8 +281,9 @@ public final class OmemoManager extends Manager {
      * @see #requestDeviceListUpdateFor(BareJid)
      * @param contact contact we want to get a set of device of.
      * @return set of known devices of that contact.
+     * @throws IOException
      */
-    public Set<OmemoDevice> getDevicesOf(BareJid contact) {
+    public Set<OmemoDevice> getDevicesOf(BareJid contact) throws IOException {
         OmemoCachedDeviceList list = getOmemoService().getOmemoStoreBackend().loadCachedDeviceList(getOwnDevice(), contact);
         HashSet<OmemoDevice> devices = new HashSet<>();
 
@@ -304,11 +307,12 @@ public final class OmemoManager extends Manager {
      * @throws SmackException.NotConnectedException
      * @throws SmackException.NoResponseException
      * @throws SmackException.NotLoggedInException
+     * @throws IOException
      */
     public OmemoMessage.Sent encrypt(BareJid recipient, String message)
             throws CryptoFailedException, UndecidedOmemoIdentityException,
             InterruptedException, SmackException.NotConnectedException,
-            SmackException.NoResponseException, SmackException.NotLoggedInException {
+            SmackException.NoResponseException, SmackException.NotLoggedInException, IOException {
         synchronized (LOCK) {
             Set<BareJid> recipients = new HashSet<>();
             recipients.add(recipient);
@@ -328,11 +332,12 @@ public final class OmemoManager extends Manager {
      * @throws SmackException.NotConnectedException
      * @throws SmackException.NoResponseException
      * @throws SmackException.NotLoggedInException
+     * @throws IOException
      */
     public OmemoMessage.Sent encrypt(Set<BareJid> recipients, String message)
             throws CryptoFailedException, UndecidedOmemoIdentityException,
             InterruptedException, SmackException.NotConnectedException,
-            SmackException.NoResponseException, SmackException.NotLoggedInException {
+            SmackException.NoResponseException, SmackException.NotLoggedInException, IOException {
         synchronized (LOCK) {
             LoggedInOmemoManager guard = new LoggedInOmemoManager(this);
             Set<OmemoDevice> devices = getDevicesOf(getOwnJid());
@@ -357,12 +362,13 @@ public final class OmemoManager extends Manager {
      * @throws SmackException.NoResponseException
      * @throws NoOmemoSupportException When the muc doesn't support OMEMO.
      * @throws SmackException.NotLoggedInException
+     * @throws IOException
      */
     public OmemoMessage.Sent encrypt(MultiUserChat muc, String message)
             throws UndecidedOmemoIdentityException, CryptoFailedException,
             XMPPException.XMPPErrorException, SmackException.NotConnectedException, InterruptedException,
             SmackException.NoResponseException, NoOmemoSupportException,
-            SmackException.NotLoggedInException {
+            SmackException.NotLoggedInException, IOException {
         synchronized (LOCK) {
             if (!multiUserChatSupportsOmemo(muc)) {
                 throw new NoOmemoSupportException();
@@ -390,10 +396,11 @@ public final class OmemoManager extends Manager {
      * @throws CorruptedOmemoKeyException if our or their key is corrupted
      * @throws NoRawSessionException if the message was not a preKeyMessage, but we had no session with the contact
      * @throws CryptoFailedException if decryption fails
+     * @throws IOException
      */
     public OmemoMessage.Received decrypt(BareJid sender, OmemoElement omemoElement)
             throws SmackException.NotLoggedInException, CorruptedOmemoKeyException, NoRawSessionException,
-            CryptoFailedException {
+            CryptoFailedException, IOException {
         LoggedInOmemoManager managerGuard = new LoggedInOmemoManager(this);
         return getOmemoService().decryptMessage(managerGuard, sender, omemoElement);
     }
@@ -404,9 +411,10 @@ public final class OmemoManager extends Manager {
      * @param mamQuery The MAM query
      * @return list of decrypted OmemoMessages
      * @throws SmackException.NotLoggedInException if the Manager is not authenticated.
+     * @throws IOException
      */
     public List<MessageOrOmemoMessage> decryptMamQueryResult(MamManager.MamQuery mamQuery)
-            throws SmackException.NotLoggedInException {
+            throws SmackException.NotLoggedInException, IOException {
         return new ArrayList<>(getOmemoService().decryptMamQueryResult(new LoggedInOmemoManager(this), mamQuery));
     }
 
@@ -486,11 +494,12 @@ public final class OmemoManager extends Manager {
      * @throws SmackException.NoResponseException
      * @throws NoSuchAlgorithmException
      * @throws SmackException.NotConnectedException
+     * @throws IOException
      */
     public void sendRatchetUpdateMessage(OmemoDevice recipient)
             throws SmackException.NotLoggedInException, CorruptedOmemoKeyException, InterruptedException,
             SmackException.NoResponseException, NoSuchAlgorithmException, SmackException.NotConnectedException,
-            CryptoFailedException, CannotEstablishOmemoSessionException {
+            CryptoFailedException, CannotEstablishOmemoSessionException, IOException {
         synchronized (LOCK) {
             Message message = new Message();
             message.setFrom(getOwnJid());
@@ -516,10 +525,11 @@ public final class OmemoManager extends Manager {
      * @throws SmackException.NoResponseException
      * @throws PubSubException.NotALeafNodeException
      * @throws XMPPException.XMPPErrorException
+     * @throws IOException
      */
     public boolean contactSupportsOmemo(BareJid contact)
             throws InterruptedException, PubSubException.NotALeafNodeException, XMPPException.XMPPErrorException,
-            SmackException.NotConnectedException, SmackException.NoResponseException {
+            SmackException.NotConnectedException, SmackException.NoResponseException, IOException {
         synchronized (LOCK) {
             OmemoCachedDeviceList deviceList = getOmemoService().refreshDeviceList(connection(), getOwnDevice(), contact);
             return !deviceList.getActiveDevices().isEmpty();
@@ -569,9 +579,10 @@ public final class OmemoManager extends Manager {
      * @return fingerprint
      * @throws SmackException.NotLoggedInException if we don't know our bareJid yet.
      * @throws CorruptedOmemoKeyException if our identityKey is corrupted.
+     * @throws IOException
      */
     public OmemoFingerprint getOwnFingerprint()
-            throws SmackException.NotLoggedInException, CorruptedOmemoKeyException {
+            throws SmackException.NotLoggedInException, CorruptedOmemoKeyException, IOException {
         synchronized (LOCK) {
             if (getOwnJid() == null) {
                 throw new SmackException.NotLoggedInException();
@@ -591,11 +602,12 @@ public final class OmemoManager extends Manager {
      * @throws SmackException.NotConnectedException
      * @throws InterruptedException
      * @throws SmackException.NoResponseException
+     * @throws IOException
      */
     public OmemoFingerprint getFingerprint(OmemoDevice device)
             throws CannotEstablishOmemoSessionException, SmackException.NotLoggedInException,
             CorruptedOmemoKeyException, SmackException.NotConnectedException, InterruptedException,
-            SmackException.NoResponseException {
+            SmackException.NoResponseException, IOException {
         synchronized (LOCK) {
             if (getOwnJid() == null) {
                 throw new SmackException.NotLoggedInException();
@@ -621,11 +633,12 @@ public final class OmemoManager extends Manager {
      * @throws SmackException.NotConnectedException
      * @throws InterruptedException
      * @throws SmackException.NoResponseException
+     * @throws IOException
      */
     public HashMap<OmemoDevice, OmemoFingerprint> getActiveFingerprints(BareJid contact)
             throws SmackException.NotLoggedInException, CorruptedOmemoKeyException,
             CannotEstablishOmemoSessionException, SmackException.NotConnectedException, InterruptedException,
-            SmackException.NoResponseException {
+            SmackException.NoResponseException, IOException {
         synchronized (LOCK) {
             if (getOwnJid() == null) {
                 throw new SmackException.NotLoggedInException();
@@ -692,10 +705,11 @@ public final class OmemoManager extends Manager {
      * @throws XMPPException.XMPPErrorException
      * @throws SmackException.NotConnectedException
      * @throws SmackException.NoResponseException
+     * @throws IOException
      */
     public void requestDeviceListUpdateFor(BareJid contact)
             throws InterruptedException, PubSubException.NotALeafNodeException, XMPPException.XMPPErrorException,
-            SmackException.NotConnectedException, SmackException.NoResponseException {
+            SmackException.NotConnectedException, SmackException.NoResponseException, IOException {
         synchronized (LOCK) {
             getOmemoService().refreshDeviceList(connection(), getOwnDevice(), contact);
         }
@@ -709,10 +723,11 @@ public final class OmemoManager extends Manager {
      * @throws XMPPException.XMPPErrorException
      * @throws SmackException.NotConnectedException
      * @throws SmackException.NoResponseException
+     * @throws IOException
      */
     public void purgeDeviceList()
             throws SmackException.NotLoggedInException, InterruptedException, XMPPException.XMPPErrorException,
-            SmackException.NotConnectedException, SmackException.NoResponseException {
+            SmackException.NotConnectedException, SmackException.NoResponseException, IOException {
         synchronized (LOCK) {
             getOmemoService().purgeDeviceList(new LoggedInOmemoManager(this));
         }
@@ -729,10 +744,11 @@ public final class OmemoManager extends Manager {
      * @throws SmackException.NotConnectedException XMPP error
      * @throws SmackException.NoResponseException XMPP error
      * @throws SmackException.NotLoggedInException
+     * @throws IOException
      */
     public void rotateSignedPreKey()
             throws CorruptedOmemoKeyException, SmackException.NotLoggedInException, XMPPException.XMPPErrorException,
-            SmackException.NotConnectedException, InterruptedException, SmackException.NoResponseException {
+            SmackException.NotConnectedException, InterruptedException, SmackException.NoResponseException, IOException {
         synchronized (LOCK) {
             if (!connection().isAuthenticated()) {
                 throw new SmackException.NotLoggedInException();
@@ -956,8 +972,8 @@ public final class OmemoManager extends Manager {
                     try {
                         getOmemoService().onOmemoMessageStanzaReceived(packet,
                                 new LoggedInOmemoManager(OmemoManager.this));
-                    } catch (SmackException.NotLoggedInException e) {
-                        LOGGER.warning("Received OMEMO stanza while being offline: " + e);
+                    } catch (SmackException.NotLoggedInException | IOException e) {
+                        LOGGER.log(Level.SEVERE, "Exception while processing OMEMO stanza", e);
                     }
                 }
             });
@@ -979,8 +995,8 @@ public final class OmemoManager extends Manager {
                         try {
                             getOmemoService().onOmemoCarbonCopyReceived(direction, carbonCopy, wrappingMessage,
                                     new LoggedInOmemoManager(OmemoManager.this));
-                        } catch (SmackException.NotLoggedInException e) {
-                            LOGGER.warning("Received OMEMO carbon copy while being offline: " + e);
+                        } catch (SmackException.NotLoggedInException | IOException e) {
+                            LOGGER.log(Level.SEVERE, "Exception while processing OMEMO stanza", e);
                         }
                     }
                 }
@@ -1018,14 +1034,23 @@ public final class OmemoManager extends Manager {
                     }
 
                     // Device List <list>
+                    OmemoCachedDeviceList deviceList;
                     OmemoDeviceListElement receivedDeviceList = (OmemoDeviceListElement) payloadItem.getPayload();
-                    getOmemoService().getOmemoStoreBackend().mergeCachedDeviceList(getOwnDevice(), from, receivedDeviceList);
+                    try {
+                        getOmemoService().getOmemoStoreBackend().mergeCachedDeviceList(getOwnDevice(), from,
+                                        receivedDeviceList);
 
-                    if (!from.asBareJid().equals(getOwnJid())) {
+                        if (!from.asBareJid().equals(getOwnJid())) {
+                            continue;
+                        }
+
+                        deviceList = getOmemoService().cleanUpDeviceList(getOwnDevice());
+                    } catch (IOException e) {
+                        LOGGER.log(Level.SEVERE,
+                                        "IOException while processing OMEMO PEP device updates. Message: " + message,
+                                        e);
                         continue;
                     }
-
-                    OmemoCachedDeviceList deviceList = getOmemoService().cleanUpDeviceList(getOwnDevice());
                     final OmemoDeviceListElement_VAxolotl newDeviceList = new OmemoDeviceListElement_VAxolotl(deviceList);
 
                     if (!newDeviceList.copyDeviceIds().equals(receivedDeviceList.copyDeviceIds())) {
diff --git a/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/OmemoRatchet.java b/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/OmemoRatchet.java
index 28ffc50ef..7ad0f6b6e 100644
--- a/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/OmemoRatchet.java
+++ b/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/OmemoRatchet.java
@@ -16,6 +16,7 @@
  */
 package org.jivesoftware.smackx.omemo;
 
+import java.io.IOException;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.List;
@@ -65,10 +66,11 @@ public abstract class OmemoRatchet<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
      * @throws NoRawSessionException when no double ratchet session was found.
      * @throws CryptoFailedException
      * @throws UntrustedOmemoIdentityException
+     * @throws IOException
      */
     public abstract byte[] doubleRatchetDecrypt(OmemoDevice sender, byte[] encryptedKey)
             throws CorruptedOmemoKeyException, NoRawSessionException, CryptoFailedException,
-            UntrustedOmemoIdentityException;
+            UntrustedOmemoIdentityException, IOException;
 
     /**
      * Encrypt a messageKey with the double ratchet session of the recipient.
@@ -86,9 +88,10 @@ public abstract class OmemoRatchet<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
      * @return tuple of cipher generated from the unpacked message key and the auth-tag
      * @throws CryptoFailedException if decryption using the double ratchet fails
      * @throws NoRawSessionException if we have no session, but the element was NOT a PreKeyMessage
+     * @throws IOException
      */
     CipherAndAuthTag retrieveMessageKeyAndAuthTag(OmemoDevice sender, OmemoElement element) throws CryptoFailedException,
-            NoRawSessionException {
+            NoRawSessionException, IOException {
         int keyId = omemoManager.getDeviceId();
         byte[] unpackedKey = null;
         List<CryptoFailedException> decryptExceptions = new ArrayList<>();
diff --git a/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/OmemoService.java b/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/OmemoService.java
index 91eb51034..1130e63fc 100644
--- a/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/OmemoService.java
+++ b/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/OmemoService.java
@@ -19,6 +19,7 @@ package org.jivesoftware.smackx.omemo;
 import static org.jivesoftware.smackx.omemo.util.OmemoConstants.Crypto.KEYLENGTH;
 import static org.jivesoftware.smackx.omemo.util.OmemoConstants.Crypto.KEYTYPE;
 
+import java.io.IOException;
 import java.security.InvalidAlgorithmParameterException;
 import java.security.InvalidKeyException;
 import java.security.NoSuchAlgorithmException;
@@ -234,11 +235,12 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
      * @throws SmackException.NotConnectedException
      * @throws SmackException.NoResponseException
      * @throws PubSubException.NotALeafNodeException
+     * @throws IOException
      */
     void init(OmemoManager.LoggedInOmemoManager managerGuard)
             throws InterruptedException, CorruptedOmemoKeyException, XMPPException.XMPPErrorException,
             SmackException.NotConnectedException, SmackException.NoResponseException,
-            PubSubException.NotALeafNodeException {
+            PubSubException.NotALeafNodeException, IOException {
 
         OmemoManager manager = managerGuard.get();
         OmemoDevice userDevice = manager.getOwnDevice();
@@ -273,12 +275,13 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
      * @throws CorruptedOmemoKeyException if our IdentityKeyPair is corrupted.
      * @throws SmackException.NotConnectedException
      * @throws CannotEstablishOmemoSessionException if session negotiation fails.
+     * @throws IOException
      */
     OmemoElement createRatchetUpdateElement(OmemoManager.LoggedInOmemoManager managerGuard,
                                             OmemoDevice contactsDevice)
             throws InterruptedException, SmackException.NoResponseException, CorruptedOmemoKeyException,
             SmackException.NotConnectedException, CannotEstablishOmemoSessionException, NoSuchAlgorithmException,
-            CryptoFailedException {
+            CryptoFailedException, IOException {
 
         OmemoManager manager = managerGuard.get();
         OmemoDevice userDevice = manager.getOwnDevice();
@@ -334,6 +337,7 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
      * @throws SmackException.NoResponseException
      * @throws UndecidedOmemoIdentityException if the list of recipient devices contains undecided devices
      * @throws CryptoFailedException if we are lacking some crypto primitives
+     * @throws IOException
      */
     private OmemoMessage.Sent encrypt(OmemoManager.LoggedInOmemoManager managerGuard,
                                       Set<OmemoDevice> contactsDevices,
@@ -341,7 +345,7 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
                                       byte[] iv,
                                       String message)
             throws SmackException.NotConnectedException, InterruptedException, SmackException.NoResponseException,
-            UndecidedOmemoIdentityException, CryptoFailedException {
+            UndecidedOmemoIdentityException, CryptoFailedException, IOException {
 
         OmemoManager manager = managerGuard.get();
         OmemoDevice userDevice = manager.getOwnDevice();
@@ -435,11 +439,12 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
      * @throws CorruptedOmemoKeyException if the identityKey of the sender is damaged.
      * @throws CryptoFailedException if decryption fails.
      * @throws NoRawSessionException if we have no session with the device and it sent a normal (non-preKey) message.
+     * @throws IOException
      */
     OmemoMessage.Received decryptMessage(OmemoManager.LoggedInOmemoManager managerGuard,
                                          BareJid senderJid,
                                          OmemoElement omemoElement)
-            throws CorruptedOmemoKeyException, CryptoFailedException, NoRawSessionException {
+            throws CorruptedOmemoKeyException, CryptoFailedException, NoRawSessionException, IOException {
 
         OmemoManager manager = managerGuard.get();
         int senderId = omemoElement.getHeader().getSid();
@@ -488,13 +493,14 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
      * @throws CryptoFailedException if we are lacking some cryptographic algorithms
      * @throws SmackException.NotConnectedException
      * @throws SmackException.NoResponseException
+     * @throws IOException
      */
     OmemoMessage.Sent createKeyTransportElement(OmemoManager.LoggedInOmemoManager managerGuard,
                                                 Set<OmemoDevice> contactsDevices,
                                                 byte[] key,
                                                 byte[] iv)
             throws InterruptedException, UndecidedOmemoIdentityException, CryptoFailedException,
-            SmackException.NotConnectedException, SmackException.NoResponseException {
+            SmackException.NotConnectedException, SmackException.NoResponseException, IOException {
         return encrypt(managerGuard, contactsDevices, key, iv, null);
     }
 
@@ -511,12 +517,13 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
      * @throws CryptoFailedException if we are lacking some cryptographic algorithms
      * @throws SmackException.NotConnectedException
      * @throws SmackException.NoResponseException
+     * @throws IOException
      */
     OmemoMessage.Sent createOmemoMessage(OmemoManager.LoggedInOmemoManager managerGuard,
                                          Set<OmemoDevice> contactsDevices,
                                          String message)
             throws InterruptedException, UndecidedOmemoIdentityException, CryptoFailedException,
-            SmackException.NotConnectedException, SmackException.NoResponseException {
+            SmackException.NotConnectedException, SmackException.NoResponseException, IOException {
 
         byte[] key, iv;
         iv = OmemoMessageBuilder.generateIv();
@@ -643,10 +650,11 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
      * @throws XMPPException.XMPPErrorException
      * @throws SmackException.NotConnectedException
      * @throws SmackException.NoResponseException
+     * @throws IOException
      */
     private void refreshAndRepublishDeviceList(XMPPConnection connection, OmemoDevice userDevice)
             throws InterruptedException, PubSubException.NotALeafNodeException, XMPPException.XMPPErrorException,
-            SmackException.NotConnectedException, SmackException.NoResponseException {
+            SmackException.NotConnectedException, SmackException.NoResponseException, IOException {
 
         // refreshOmemoDeviceList;
         OmemoDeviceListElement publishedList;
@@ -685,8 +693,9 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
      *
      * @param userDevice
      * @return
+     * @throws IOException
      */
-    OmemoCachedDeviceList cleanUpDeviceList(OmemoDevice userDevice) {
+    OmemoCachedDeviceList cleanUpDeviceList(OmemoDevice userDevice) throws IOException {
         OmemoCachedDeviceList cachedDeviceList;
 
         // Delete stale devices if allowed and necessary
@@ -719,10 +728,11 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
      * @throws XMPPException.XMPPErrorException
      * @throws SmackException.NotConnectedException
      * @throws SmackException.NoResponseException
+     * @throws IOException
      */
     OmemoCachedDeviceList refreshDeviceList(XMPPConnection connection, OmemoDevice userDevice, BareJid contact)
             throws InterruptedException, PubSubException.NotALeafNodeException, XMPPException.XMPPErrorException,
-            SmackException.NotConnectedException, SmackException.NoResponseException {
+            SmackException.NotConnectedException, SmackException.NoResponseException, IOException {
         // refreshOmemoDeviceList;
         OmemoDeviceListElement publishedList;
         try {
@@ -790,11 +800,12 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
      * @throws SmackException.NotConnectedException
      * @throws InterruptedException
      * @throws SmackException.NoResponseException
+     * @throws IOException
      */
     private Set<OmemoDevice> buildMissingSessionsWithDevices(XMPPConnection connection,
                                                              OmemoDevice userDevice,
                                                              Set<OmemoDevice> devices)
-            throws SmackException.NotConnectedException, InterruptedException, SmackException.NoResponseException {
+            throws SmackException.NotConnectedException, InterruptedException, SmackException.NoResponseException, IOException {
 
         Set<OmemoDevice> devicesWithSession = new HashSet<>();
         for (OmemoDevice device : devices) {
@@ -828,8 +839,9 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
      * @param callback OmemoTrustCallback to query the trust decisions from
      * @param devices set of OmemoDevices
      * @return set of OmemoDevices which contains all devices from the set devices, which are undecided
+     * @throws IOException
      */
-    private Set<OmemoDevice> getUndecidedDevices(OmemoDevice userDevice, OmemoTrustCallback callback, Set<OmemoDevice> devices) {
+    private Set<OmemoDevice> getUndecidedDevices(OmemoDevice userDevice, OmemoTrustCallback callback, Set<OmemoDevice> devices) throws IOException {
         Set<OmemoDevice> undecidedDevices = new HashSet<>();
 
         for (OmemoDevice device : devices) {
@@ -858,8 +870,9 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
      * @param userDevice our OmemoDevice.
      * @param contactsDevice OmemoDevice of the contact.
      * @return true if userDevice has session with contactsDevice.
+     * @throws IOException
      */
-    private boolean hasSession(OmemoDevice userDevice, OmemoDevice contactsDevice) {
+    private boolean hasSession(OmemoDevice userDevice, OmemoDevice contactsDevice) throws IOException {
         return getOmemoStoreBackend().loadRawSession(userDevice, contactsDevice) != null;
     }
 
@@ -881,8 +894,9 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
      *
      * @param userDevice our OmemoDevice
      * @return true if rotation is necessary
+     * @throws IOException
      */
-    private boolean shouldRotateSignedPreKey(OmemoDevice userDevice) {
+    private boolean shouldRotateSignedPreKey(OmemoDevice userDevice) throws IOException {
         if (!OmemoConfiguration.getRenewOldSignedPreKeys()) {
             return false;
         }
@@ -909,8 +923,9 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
      *
      * @param userDevice our OmemoDevice
      * @return our altered deviceList with stale devices marked as inactive.
+     * @throws IOException
      */
-    private OmemoCachedDeviceList deleteStaleDevices(OmemoDevice userDevice) {
+    private OmemoCachedDeviceList deleteStaleDevices(OmemoDevice userDevice) throws IOException {
         OmemoCachedDeviceList deviceList = getOmemoStoreBackend().loadCachedDeviceList(userDevice);
         int maxAgeHours = OmemoConfiguration.getDeleteStaleDevicesAfterHours();
         return removeStaleDevicesFromDeviceList(userDevice, userDevice.getJid(), deviceList, maxAgeHours);
@@ -928,11 +943,12 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
      * @param contact subjects BareJid.
      * @param contactsDeviceList subjects deviceList.
      * @return copy of subjects deviceList with stale devices marked as inactive.
+     * @throws IOException
      */
     private OmemoCachedDeviceList removeStaleDevicesFromDeviceList(OmemoDevice userDevice,
                                                                    BareJid contact,
                                                                    OmemoCachedDeviceList contactsDeviceList,
-                                                                   int maxAgeHours) {
+                                                                   int maxAgeHours) throws IOException {
         OmemoCachedDeviceList deviceList = new OmemoCachedDeviceList(contactsDeviceList); // Don't work on original list.
 
         // Iterate through original list, but modify copy instead
@@ -1024,9 +1040,10 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
      * @param managerGuard authenticated OmemoManager.
      * @param mamQuery Mam archive query
      * @return list of {@link MessageOrOmemoMessage}s.
+     * @throws IOException
      */
     List<MessageOrOmemoMessage> decryptMamQueryResult(OmemoManager.LoggedInOmemoManager managerGuard,
-                                                      MamManager.MamQuery mamQuery) {
+                                                      MamManager.MamQuery mamQuery) throws IOException {
         List<MessageOrOmemoMessage> result = new ArrayList<>();
         for (Message message : mamQuery.getMessages()) {
             if (OmemoManager.stanzaContainsOmemoElement(message)) {
@@ -1055,7 +1072,7 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
     public void onOmemoCarbonCopyReceived(CarbonExtension.Direction direction,
                                           Message carbonCopy,
                                           Message wrappingMessage,
-                                          OmemoManager.LoggedInOmemoManager managerGuard) {
+                                          OmemoManager.LoggedInOmemoManager managerGuard) throws IOException {
         OmemoManager manager = managerGuard.get();
         // Avoid the ratchet being manipulated and the bundle being published multiple times simultaneously
         synchronized (manager.LOCK) {
@@ -1110,7 +1127,7 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
     }
 
     @Override
-    public void onOmemoMessageStanzaReceived(Stanza stanza, OmemoManager.LoggedInOmemoManager managerGuard) {
+    public void onOmemoMessageStanzaReceived(Stanza stanza, OmemoManager.LoggedInOmemoManager managerGuard) throws IOException {
         OmemoManager manager = managerGuard.get();
         // Avoid the ratchet being manipulated and the bundle being published multiple times simultaneously
         synchronized (manager.LOCK) {
@@ -1197,8 +1214,9 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
      * @param stanza stanza
      * @param managerGuard authenticated OmemoManager
      * @return decrypted OmemoMessage or null
+     * @throws IOException
      */
-    OmemoMessage.Received decryptStanza(Stanza stanza, OmemoManager.LoggedInOmemoManager managerGuard) {
+    OmemoMessage.Received decryptStanza(Stanza stanza, OmemoManager.LoggedInOmemoManager managerGuard) throws IOException {
         OmemoManager manager = managerGuard.get();
         // Avoid the ratchet being manipulated and the bundle being published multiple times simultaneously
         synchronized (manager.LOCK) {
@@ -1275,9 +1293,10 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
      *
      * @param managerGuard authenticated OmemoManager.
      * @param brokenDevice device which session broke.
+     * @throws IOException
      */
     private void repairBrokenSessionWithPreKeyMessage(OmemoManager.LoggedInOmemoManager managerGuard,
-                                                      OmemoDevice brokenDevice) {
+                                                      OmemoDevice brokenDevice) throws IOException {
 
         LOGGER.log(Level.WARNING, "Attempt to repair the session by sending a fresh preKey message to "
                 + brokenDevice);
@@ -1307,11 +1326,12 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
      * @throws SmackException.NotConnectedException
      * @throws CryptoFailedException if encryption fails (should not happen though, but who knows...)
      * @throws CannotEstablishOmemoSessionException if we cannot establish a session with contactsDevice.
+     * @throws IOException
      */
     private void sendRatchetUpdate(OmemoManager.LoggedInOmemoManager managerGuard, OmemoDevice contactsDevice)
             throws CorruptedOmemoKeyException, InterruptedException, SmackException.NoResponseException,
             NoSuchAlgorithmException, SmackException.NotConnectedException, CryptoFailedException,
-            CannotEstablishOmemoSessionException {
+            CannotEstablishOmemoSessionException, IOException {
 
         OmemoManager manager = managerGuard.get();
         OmemoElement ratchetUpdate = createRatchetUpdateElement(managerGuard, contactsDevice);
@@ -1350,10 +1370,11 @@ public abstract class OmemoService<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey,
      * @throws XMPPException.XMPPErrorException
      * @throws SmackException.NotConnectedException
      * @throws SmackException.NoResponseException
+     * @throws IOException
      */
     public void purgeDeviceList(OmemoManager.LoggedInOmemoManager managerGuard)
             throws InterruptedException, XMPPException.XMPPErrorException, SmackException.NotConnectedException,
-            SmackException.NoResponseException {
+            SmackException.NoResponseException, IOException {
 
         OmemoManager omemoManager = managerGuard.get();
         OmemoDevice userDevice = omemoManager.getOwnDevice();
diff --git a/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/OmemoStore.java b/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/OmemoStore.java
index 033db6994..9da60104e 100644
--- a/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/OmemoStore.java
+++ b/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/OmemoStore.java
@@ -18,6 +18,7 @@ package org.jivesoftware.smackx.omemo;
 
 import static org.jivesoftware.smackx.omemo.util.OmemoConstants.PRE_KEY_COUNT_PER_BUNDLE;
 
+import java.io.IOException;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.Map;
@@ -78,8 +79,9 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @param userDevice    our current device.
      * @param id            deviceId to check for.
      * @return true if list did not contain our id, else false
+     * @throws IOException
      */
-    boolean isAvailableDeviceId(OmemoDevice userDevice, int id) {
+    boolean isAvailableDeviceId(OmemoDevice userDevice, int id) throws IOException {
         LOGGER.log(Level.INFO, "Check if id " + id + " is available...");
 
         // Lookup local cached device list
@@ -101,8 +103,9 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @param userDevice our OmemoDevice.
      * @param contact Contact we received the list from.
      * @param list    List we received.
+     * @throws IOException
      */
-    OmemoCachedDeviceList mergeCachedDeviceList(OmemoDevice userDevice, BareJid contact, OmemoDeviceListElement list) {
+    OmemoCachedDeviceList mergeCachedDeviceList(OmemoDevice userDevice, BareJid contact, OmemoDeviceListElement list) throws IOException {
         OmemoCachedDeviceList cached = loadCachedDeviceList(userDevice, contact);
 
         if (cached == null) {
@@ -131,10 +134,11 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      *
      * @param userDevice our OmemoDevice.
      * @throws CorruptedOmemoKeyException when our identityKey is invalid.
+     * @throws IOException
      * @throws IllegalStateException when our IdentityKeyPair is null.
      */
     void changeSignedPreKey(OmemoDevice userDevice)
-            throws CorruptedOmemoKeyException {
+            throws CorruptedOmemoKeyException, IOException {
 
         T_IdKeyPair idKeyPair = loadOmemoIdentityKeyPair(userDevice);
         if (idKeyPair == null) {
@@ -159,8 +163,9 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * Remove the oldest signedPreKey until there are only MAX_NUMBER_OF_STORED_SIGNED_PREKEYS left.
      *
      * @param userDevice our OmemoDevice.
+     * @throws IOException
      */
-    private void removeOldSignedPreKeys(OmemoDevice userDevice) {
+    private void removeOldSignedPreKeys(OmemoDevice userDevice) throws IOException {
         if (OmemoConfiguration.getMaxNumberOfStoredSignedPreKeys() <= 0) {
             return;
         }
@@ -181,9 +186,10 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @param userDevice our OmemoDevice.
      * @return OmemoBundleElement
      * @throws CorruptedOmemoKeyException when a key could not be loaded
+     * @throws IOException
      */
     OmemoBundleElement_VAxolotl packOmemoBundle(OmemoDevice userDevice)
-            throws CorruptedOmemoKeyException {
+            throws CorruptedOmemoKeyException, IOException {
 
         int currentSignedPreKeyId = loadCurrentOmemoSignedPreKeyId(userDevice);
         T_SigPreKey currentSignedPreKey = loadOmemoSignedPreKeys(userDevice).get(currentSignedPreKeyId);
@@ -201,9 +207,10 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * Replenish our supply of keys. If we are missing any type of keys, generate them fresh.
      * @param userDevice
      * @throws CorruptedOmemoKeyException
+     * @throws IOException
      */
     public void replenishKeys(OmemoDevice userDevice)
-            throws CorruptedOmemoKeyException {
+            throws CorruptedOmemoKeyException, IOException {
 
         T_IdKeyPair identityKeyPair = loadOmemoIdentityKeyPair(userDevice);
         if (identityKeyPair == null) {
@@ -244,9 +251,10 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @param userDevice our OmemoDevice.
      * @return identityKeyPair
      * @throws CorruptedOmemoKeyException Thrown, if the stored key is damaged (*hands up* not my fault!)
+     * @throws IOException
      */
     public abstract T_IdKeyPair loadOmemoIdentityKeyPair(OmemoDevice userDevice)
-            throws CorruptedOmemoKeyException;
+            throws CorruptedOmemoKeyException, IOException;
 
     /**
      * Store our identityKeyPair in storage. It would be a cool feature, if the key could be stored in a encrypted
@@ -254,8 +262,9 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      *
      * @param userDevice our OmemoDevice.
      * @param identityKeyPair identityKeyPair
+     * @throws IOException
      */
-    public abstract void storeOmemoIdentityKeyPair(OmemoDevice userDevice, T_IdKeyPair identityKeyPair);
+    public abstract void storeOmemoIdentityKeyPair(OmemoDevice userDevice, T_IdKeyPair identityKeyPair) throws IOException;
 
     /**
      * Remove the identityKeyPair of a user.
@@ -270,9 +279,10 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @param contactsDevice the device of which we want to load the identityKey.
      * @return identityKey
      * @throws CorruptedOmemoKeyException when the key in question is corrupted and cant be deserialized.
+     * @throws IOException
      */
     public abstract T_IdKey loadOmemoIdentityKey(OmemoDevice userDevice, OmemoDevice contactsDevice)
-            throws CorruptedOmemoKeyException;
+            throws CorruptedOmemoKeyException, IOException;
 
     /**
      * Store the public identityKey of the device.
@@ -280,8 +290,9 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @param userDevice our OmemoDevice.
      * @param contactsDevice device.
      * @param contactsKey    identityKey belonging to the contactsDevice.
+     * @throws IOException
      */
-    public abstract void storeOmemoIdentityKey(OmemoDevice userDevice, OmemoDevice contactsDevice, T_IdKey contactsKey);
+    public abstract void storeOmemoIdentityKey(OmemoDevice userDevice, OmemoDevice contactsDevice, T_IdKey contactsKey) throws IOException;
 
     /**
      * Removes the identityKey of a device.
@@ -298,8 +309,9 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @param userDevice our omemoDevice.
      * @param contactsDevice device of which we want to set the message counter.
      * @param counter counter value.
+     * @throws IOException
      */
-    public abstract void storeOmemoMessageCounter(OmemoDevice userDevice, OmemoDevice contactsDevice, int counter);
+    public abstract void storeOmemoMessageCounter(OmemoDevice userDevice, OmemoDevice contactsDevice, int counter) throws IOException;
 
     /**
      * Return the current value of the message counter.
@@ -309,8 +321,9 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @param userDevice our omemoDevice
      * @param contactsDevice device of which we want to get the message counter.
      * @return counter value.
+     * @throws IOException
      */
-    public abstract int loadOmemoMessageCounter(OmemoDevice userDevice, OmemoDevice contactsDevice);
+    public abstract int loadOmemoMessageCounter(OmemoDevice userDevice, OmemoDevice contactsDevice) throws IOException;
 
     /**
      * Set the date of the last message that was received from a device.
@@ -318,8 +331,9 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @param userDevice omemoManager of our device.
      * @param contactsDevice device in question
      * @param date date of the last received message
+     * @throws IOException
      */
-    public abstract void setDateOfLastReceivedMessage(OmemoDevice userDevice, OmemoDevice contactsDevice, Date date);
+    public abstract void setDateOfLastReceivedMessage(OmemoDevice userDevice, OmemoDevice contactsDevice, Date date) throws IOException;
 
     /**
      * Return the date of the last message that was received from device 'from'.
@@ -327,8 +341,9 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @param userDevice our OmemoDevice.
      * @param contactsDevice device in question
      * @return date if existent, null
+     * @throws IOException
      */
-    public abstract Date getDateOfLastReceivedMessage(OmemoDevice userDevice, OmemoDevice contactsDevice);
+    public abstract Date getDateOfLastReceivedMessage(OmemoDevice userDevice, OmemoDevice contactsDevice) throws IOException;
 
     /**
      * Set the date of the last time the deviceId was published. This method only gets called, when the deviceId
@@ -337,8 +352,9 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @param userDevice our OmemoDevice
      * @param contactsDevice OmemoDevice in question
      * @param date date of the last publication after not being published
+     * @throws IOException
      */
-    public abstract void setDateOfLastDeviceIdPublication(OmemoDevice userDevice, OmemoDevice contactsDevice, Date date);
+    public abstract void setDateOfLastDeviceIdPublication(OmemoDevice userDevice, OmemoDevice contactsDevice, Date date) throws IOException;
 
     /**
      * Return the date of the last time the deviceId was published after previously being not published.
@@ -347,24 +363,27 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @param userDevice our OmemoDevice
      * @param contactsDevice OmemoDevice in question
      * @return date of the last publication after not being published
+     * @throws IOException
      */
-    public abstract Date getDateOfLastDeviceIdPublication(OmemoDevice userDevice, OmemoDevice contactsDevice);
+    public abstract Date getDateOfLastDeviceIdPublication(OmemoDevice userDevice, OmemoDevice contactsDevice) throws IOException;
 
     /**
      * Set the date of the last time the signed preKey was renewed.
      *
      * @param userDevice our OmemoDevice.
      * @param date date
+     * @throws IOException
      */
-    public abstract void setDateOfLastSignedPreKeyRenewal(OmemoDevice userDevice, Date date);
+    public abstract void setDateOfLastSignedPreKeyRenewal(OmemoDevice userDevice, Date date) throws IOException;
 
     /**
      * Get the date of the last time the signed preKey was renewed.
      *
      * @param userDevice our OmemoDevice.
      * @return date if existent, otherwise null
+     * @throws IOException
      */
-    public abstract Date getDateOfLastSignedPreKeyRenewal(OmemoDevice userDevice);
+    public abstract Date getDateOfLastSignedPreKeyRenewal(OmemoDevice userDevice) throws IOException;
 
     /**
      * Generate 'count' new PreKeys beginning with id 'startId'.
@@ -384,8 +403,9 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @param userDevice our OmemoDevice.
      * @param preKeyId id of the key to be loaded
      * @return loaded preKey
+     * @throws IOException
      */
-    public abstract T_PreKey loadOmemoPreKey(OmemoDevice userDevice, int preKeyId);
+    public abstract T_PreKey loadOmemoPreKey(OmemoDevice userDevice, int preKeyId) throws IOException;
 
     /**
      * Store a PreKey in storage.
@@ -393,16 +413,18 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @param userDevice our OmemoDevice.
      * @param preKeyId id of the key
      * @param preKey   key
+     * @throws IOException
      */
-    public abstract void storeOmemoPreKey(OmemoDevice userDevice, int preKeyId, T_PreKey preKey);
+    public abstract void storeOmemoPreKey(OmemoDevice userDevice, int preKeyId, T_PreKey preKey) throws IOException;
 
     /**
      * Store a whole bunch of preKeys.
      *
      * @param userDevice our OmemoDevice.
      * @param preKeyHashMap HashMap of preKeys
+     * @throws IOException
      */
-    public void storeOmemoPreKeys(OmemoDevice userDevice, TreeMap<Integer, T_PreKey> preKeyHashMap) {
+    public void storeOmemoPreKeys(OmemoDevice userDevice, TreeMap<Integer, T_PreKey> preKeyHashMap) throws IOException {
         for (Map.Entry<Integer, T_PreKey> entry : preKeyHashMap.entrySet()) {
             storeOmemoPreKey(userDevice, entry.getKey(), entry.getValue());
         }
@@ -422,8 +444,9 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      *
      * @param userDevice our OmemoDevice.
      * @return Map containing our preKeys
+     * @throws IOException
      */
-    public abstract TreeMap<Integer, T_PreKey> loadOmemoPreKeys(OmemoDevice userDevice);
+    public abstract TreeMap<Integer, T_PreKey> loadOmemoPreKeys(OmemoDevice userDevice) throws IOException;
 
     /**
      * Return the signedPreKey with the id 'singedPreKeyId'.
@@ -431,10 +454,11 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @param userDevice our OmemoDevice.
      * @param signedPreKeyId id of the key
      * @return key
+     * @throws IOException
      */
-    public abstract T_SigPreKey loadOmemoSignedPreKey(OmemoDevice userDevice, int signedPreKeyId);
+    public abstract T_SigPreKey loadOmemoSignedPreKey(OmemoDevice userDevice, int signedPreKeyId) throws IOException;
 
-    public int loadCurrentOmemoSignedPreKeyId(OmemoDevice userDevice) {
+    public int loadCurrentOmemoSignedPreKeyId(OmemoDevice userDevice) throws IOException {
         return loadOmemoSignedPreKeys(userDevice).lastKey();
     }
 
@@ -443,8 +467,9 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      *
      * @param userDevice our OmemoDevice.
      * @return HashMap of our singedPreKeys
+     * @throws IOException
      */
-    public abstract TreeMap<Integer, T_SigPreKey> loadOmemoSignedPreKeys(OmemoDevice userDevice);
+    public abstract TreeMap<Integer, T_SigPreKey> loadOmemoSignedPreKeys(OmemoDevice userDevice) throws IOException;
 
     /**
      * Generate a new signed preKey.
@@ -465,8 +490,9 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @param userDevice our OmemoDevice.
      * @param signedPreKeyId id of the signedPreKey
      * @param signedPreKey   the key itself
+     * @throws IOException
      */
-    public abstract void storeOmemoSignedPreKey(OmemoDevice userDevice, int signedPreKeyId, T_SigPreKey signedPreKey);
+    public abstract void storeOmemoSignedPreKey(OmemoDevice userDevice, int signedPreKeyId, T_SigPreKey signedPreKey) throws IOException;
 
     /**
      * Remove a signedPreKey from storage.
@@ -482,8 +508,9 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @param userDevice our OmemoDevice.
      * @param contactsDevice device whose session we want to load
      * @return crypto related session
+     * @throws IOException
      */
-    public abstract T_Sess loadRawSession(OmemoDevice userDevice, OmemoDevice contactsDevice);
+    public abstract T_Sess loadRawSession(OmemoDevice userDevice, OmemoDevice contactsDevice) throws IOException;
 
     /**
      * Load all crypto-lib specific session objects of contact 'contact'.
@@ -491,8 +518,9 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @param userDevice our OmemoDevice.
      * @param contact BareJid of the contact we want to get all sessions from
      * @return TreeMap of deviceId and sessions of the contact
+     * @throws IOException
      */
-    public abstract HashMap<Integer, T_Sess> loadAllRawSessionsOf(OmemoDevice userDevice, BareJid contact);
+    public abstract HashMap<Integer, T_Sess> loadAllRawSessionsOf(OmemoDevice userDevice, BareJid contact) throws IOException;
 
     /**
      * Store a crypto-lib specific session to storage.
@@ -500,8 +528,9 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @param userDevice our OmemoDevice.
      * @param contactsDevice  OmemoDevice whose session we want to store
      * @param session session
+     * @throws IOException
      */
-    public abstract void storeRawSession(OmemoDevice userDevice, OmemoDevice contactsDevice, T_Sess session);
+    public abstract void storeRawSession(OmemoDevice userDevice, OmemoDevice contactsDevice, T_Sess session) throws IOException;
 
     /**
      * Remove a crypto-lib specific session from storage.
@@ -535,15 +564,17 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @param userDevice our OmemoDevice.
      * @param contact contact we want to get the deviceList of
      * @return CachedDeviceList of the contact
+     * @throws IOException
      */
-    public abstract OmemoCachedDeviceList loadCachedDeviceList(OmemoDevice userDevice, BareJid contact);
+    public abstract OmemoCachedDeviceList loadCachedDeviceList(OmemoDevice userDevice, BareJid contact) throws IOException;
 
     /**
      * Load a list of deviceIds from our own devices.
      * @param userDevice
      * @return
+     * @throws IOException
      */
-    public OmemoCachedDeviceList loadCachedDeviceList(OmemoDevice userDevice) {
+    public OmemoCachedDeviceList loadCachedDeviceList(OmemoDevice userDevice) throws IOException {
         return loadCachedDeviceList(userDevice, userDevice.getJid());
     }
 
@@ -554,10 +585,11 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @param userDevice our OmemoDevice.
      * @param contact    Contact
      * @param contactsDeviceList list of the contacts devices' ids.
+     * @throws IOException
      */
     public abstract void storeCachedDeviceList(OmemoDevice userDevice,
                                                BareJid contact,
-                                               OmemoCachedDeviceList contactsDeviceList);
+                                               OmemoCachedDeviceList contactsDeviceList) throws IOException;
 
     /**
      * Delete this device's IdentityKey, PreKeys, SignedPreKeys and Sessions.
@@ -580,9 +612,10 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @return fingerprint of our identityKeyPair
      *
      * @throws CorruptedOmemoKeyException if the identityKey of userDevice is corrupted.
+     * @throws IOException
      */
     public OmemoFingerprint getFingerprint(OmemoDevice userDevice)
-            throws CorruptedOmemoKeyException {
+            throws CorruptedOmemoKeyException, IOException {
 
         T_IdKeyPair keyPair = loadOmemoIdentityKeyPair(userDevice);
         if (keyPair == null) {
@@ -600,9 +633,10 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @return fingerprint of the userDevices IdentityKey.
      * @throws CorruptedOmemoKeyException if the IdentityKey is corrupted.
      * @throws NoIdentityKeyException if no IdentityKey for contactsDevice has been found locally.
+     * @throws IOException
      */
     public OmemoFingerprint getFingerprint(OmemoDevice userDevice, OmemoDevice contactsDevice)
-            throws CorruptedOmemoKeyException, NoIdentityKeyException {
+            throws CorruptedOmemoKeyException, NoIdentityKeyException, IOException {
 
         T_IdKey identityKey = loadOmemoIdentityKey(userDevice, contactsDevice);
         if (identityKey == null) {
@@ -625,10 +659,11 @@ public abstract class OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @throws SmackException.NotConnectedException
      * @throws InterruptedException
      * @throws SmackException.NoResponseException
+     * @throws IOException
      */
     public OmemoFingerprint getFingerprintAndMaybeBuildSession(OmemoManager.LoggedInOmemoManager managerGuard, OmemoDevice contactsDevice)
             throws CannotEstablishOmemoSessionException, CorruptedOmemoKeyException,
-            SmackException.NotConnectedException, InterruptedException, SmackException.NoResponseException {
+            SmackException.NotConnectedException, InterruptedException, SmackException.NoResponseException, IOException {
         OmemoManager omemoManager = managerGuard.get();
 
         // Load identityKey
diff --git a/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/internal/listener/OmemoCarbonCopyStanzaReceivedListener.java b/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/internal/listener/OmemoCarbonCopyStanzaReceivedListener.java
index 4d766025c..cdfc31389 100644
--- a/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/internal/listener/OmemoCarbonCopyStanzaReceivedListener.java
+++ b/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/internal/listener/OmemoCarbonCopyStanzaReceivedListener.java
@@ -16,6 +16,8 @@
  */
 package org.jivesoftware.smackx.omemo.internal.listener;
 
+import java.io.IOException;
+
 import org.jivesoftware.smack.packet.Message;
 
 import org.jivesoftware.smackx.carbons.packet.CarbonExtension;
@@ -26,5 +28,6 @@ import org.jivesoftware.smackx.omemo.OmemoManager;
  */
 public interface OmemoCarbonCopyStanzaReceivedListener {
 
-    void onOmemoCarbonCopyReceived(CarbonExtension.Direction direction, Message carbonCopy, Message wrappingMessage, OmemoManager.LoggedInOmemoManager omemoManager);
+    void onOmemoCarbonCopyReceived(CarbonExtension.Direction direction, Message carbonCopy, Message wrappingMessage,
+                    OmemoManager.LoggedInOmemoManager omemoManager) throws IOException;
 }
diff --git a/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/internal/listener/OmemoMessageStanzaReceivedListener.java b/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/internal/listener/OmemoMessageStanzaReceivedListener.java
index 031f259d8..c6d7ecc58 100644
--- a/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/internal/listener/OmemoMessageStanzaReceivedListener.java
+++ b/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/internal/listener/OmemoMessageStanzaReceivedListener.java
@@ -16,11 +16,13 @@
  */
 package org.jivesoftware.smackx.omemo.internal.listener;
 
+import java.io.IOException;
+
 import org.jivesoftware.smack.packet.Stanza;
 
 import org.jivesoftware.smackx.omemo.OmemoManager;
 
 public interface OmemoMessageStanzaReceivedListener {
 
-    void onOmemoMessageStanzaReceived(Stanza stanza, OmemoManager.LoggedInOmemoManager omemoManager);
+    void onOmemoMessageStanzaReceived(Stanza stanza, OmemoManager.LoggedInOmemoManager omemoManager) throws IOException;
 }
diff --git a/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/util/OmemoMessageBuilder.java b/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/util/OmemoMessageBuilder.java
index 197aab42d..043d6a32b 100644
--- a/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/util/OmemoMessageBuilder.java
+++ b/smack-omemo/src/main/java/org/jivesoftware/smackx/omemo/util/OmemoMessageBuilder.java
@@ -20,6 +20,7 @@ import static org.jivesoftware.smackx.omemo.util.OmemoConstants.Crypto.CIPHERMOD
 import static org.jivesoftware.smackx.omemo.util.OmemoConstants.Crypto.KEYLENGTH;
 import static org.jivesoftware.smackx.omemo.util.OmemoConstants.Crypto.KEYTYPE;
 
+import java.io.IOException;
 import java.io.UnsupportedEncodingException;
 import java.nio.charset.StandardCharsets;
 import java.security.InvalidAlgorithmParameterException;
@@ -219,10 +220,11 @@ public class OmemoMessageBuilder<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_
      * @throws CorruptedOmemoKeyException if the identityKey of that device is corrupted.
      * @throws UndecidedOmemoIdentityException if the user hasn't yet decided whether to trust that device or not.
      * @throws UntrustedOmemoIdentityException if the user has decided not to trust that device.
+     * @throws IOException
      */
     public void addRecipient(OmemoDevice contactsDevice)
             throws NoIdentityKeyException, CorruptedOmemoKeyException, UndecidedOmemoIdentityException,
-            UntrustedOmemoIdentityException {
+            UntrustedOmemoIdentityException, IOException {
 
         OmemoFingerprint fingerprint;
         fingerprint = OmemoService.getInstance().getOmemoStoreBackend().getFingerprint(userDevice, contactsDevice);
diff --git a/smack-omemo/src/test/java/org/jivesoftware/smackx/omemo/OmemoStoreTest.java b/smack-omemo/src/test/java/org/jivesoftware/smackx/omemo/OmemoStoreTest.java
index 369c682d9..96b9be7fc 100644
--- a/smack-omemo/src/test/java/org/jivesoftware/smackx/omemo/OmemoStoreTest.java
+++ b/smack-omemo/src/test/java/org/jivesoftware/smackx/omemo/OmemoStoreTest.java
@@ -302,20 +302,20 @@ public abstract class OmemoStoreTest<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey
     }
 
     @Test
-    public void loadAllRawSessionsReturnsEmptyMapTest() {
+    public void loadAllRawSessionsReturnsEmptyMapTest() throws IOException {
         HashMap<Integer, T_Sess> sessions = store.loadAllRawSessionsOf(alice, bob.getJid());
         assertNotNull(sessions);
         assertEquals(0, sessions.size());
     }
 
     @Test
-    public void loadNonExistentRawSessionReturnsNullTest() {
+    public void loadNonExistentRawSessionReturnsNullTest() throws IOException {
         T_Sess session = store.loadRawSession(alice, bob);
         assertNull(session);
     }
 
     @Test
-    public void loadStoreMessageCounterTest() {
+    public void loadStoreMessageCounterTest() throws IOException {
         assertEquals(0, store.loadOmemoMessageCounter(alice, bob));
         store.storeOmemoMessageCounter(alice, bob, 20);
         assertEquals(20, store.loadOmemoMessageCounter(alice, bob));