Merge branch 'trz/rebase' into trz/rename

9 files changed, 2242 insertions, 0 deletions

diff --git a/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/AxolotlService.java b/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/AxolotlService.java
new file mode 100644
index 00000000..987cf940
--- /dev/null
+++ b/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/AxolotlService.java
@@ -0,0 +1,110 @@
+package de.thedevstack.conversationsplus.crypto.axolotl;
+
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+
+import org.whispersystems.libaxolotl.AxolotlAddress;
+import org.whispersystems.libaxolotl.IdentityKey;
+import org.whispersystems.libaxolotl.state.PreKeyRecord;
+import org.whispersystems.libaxolotl.state.SignedPreKeyRecord;
+
+import java.security.cert.X509Certificate;
+import java.util.Set;
+
+import de.thedevstack.conversationsplus.entities.Account;
+import de.thedevstack.conversationsplus.entities.Contact;
+import de.thedevstack.conversationsplus.entities.Conversation;
+import de.thedevstack.conversationsplus.entities.Message;
+import de.thedevstack.conversationsplus.xmpp.OnAdvancedStreamFeaturesLoaded;
+import de.thedevstack.conversationsplus.xmpp.jid.Jid;
+
+/**
+ * Created by tzur on 02.03.2016.
+ */
+public interface AxolotlService extends OnAdvancedStreamFeaturesLoaded {
+
+	String LOGPREFIX = "AxolotlService";
+
+	String PEP_PREFIX = "eu.siacs.conversations.axolotl";
+	String PEP_DEVICE_LIST = PEP_PREFIX + ".devicelist";
+	String PEP_BUNDLES = PEP_PREFIX + ".bundles";
+	String PEP_VERIFICATION = PEP_PREFIX + ".verification";
+
+	enum FetchStatus {
+		PENDING,
+		SUCCESS,
+		SUCCESS_VERIFIED,
+		TIMEOUT,
+		ERROR
+	}
+
+	boolean fetchMapHasErrors(Contact contact);
+
+	String getOwnFingerprint();
+
+	Set<IdentityKey> getKeysWithTrust(XmppAxolotlSession.Trust trust);
+
+	Set<IdentityKey> getKeysWithTrust(XmppAxolotlSession.Trust trust, Contact contact);
+
+	long getNumTrustedKeys(Contact contact);
+
+	Set<String> getFingerprintsForOwnSessions();
+
+	Set<String> getFingerprintsForContact(Contact contact);
+
+	boolean isPepBroken();
+
+	void regenerateKeys(boolean wipeOther);
+
+	int getOwnDeviceId();
+
+	Set<Integer> getOwnDeviceIds();
+
+	void registerDevices(Jid jid, @NonNull Set<Integer> deviceIds);
+
+	void wipeOtherPepDevices();
+
+	void purgeKey(String fingerprint);
+
+	void publishOwnDeviceIdIfNeeded();
+
+	void publishOwnDeviceId(Set<Integer> deviceIds);
+
+	void publishDeviceVerificationAndBundle(SignedPreKeyRecord signedPreKeyRecord,
+											Set<PreKeyRecord> preKeyRecords,
+											boolean announceAfter,
+											boolean wipe);
+
+	void publishBundlesIfNeeded(boolean announce, boolean wipe);
+
+	boolean isContactAxolotlCapable(Contact contact);
+
+	XmppAxolotlSession.Trust getFingerprintTrust(String fingerprint);
+
+	X509Certificate getFingerprintCertificate(String fingerprint);
+
+	void setFingerprintTrust(String fingerprint, XmppAxolotlSession.Trust trust);
+
+	Set<AxolotlAddress> findDevicesWithoutSession(Conversation conversation);
+
+	Set<AxolotlAddress> findDevicesWithoutSession(Jid contactJid);
+
+	boolean createSessionsIfNeeded(Conversation conversation);
+
+	boolean trustedSessionVerified(Conversation conversation);
+
+	boolean hasPendingKeyFetches(Account account, Contact contact);
+
+	@Nullable
+	XmppAxolotlMessage encrypt(Message message);
+
+	void preparePayloadMessage(Message message, boolean delay);
+
+	void prepareKeyTransportMessage(Contact contact, OnMessageCreatedCallback onMessageCreatedCallback);
+
+	XmppAxolotlMessage fetchAxolotlMessageFromCache(Message message);
+
+	XmppAxolotlMessage.XmppAxolotlPlaintextMessage processReceivingPayloadMessage(XmppAxolotlMessage message);
+
+	XmppAxolotlMessage.XmppAxolotlKeyTransportMessage processReceivingKeyTransportMessage(XmppAxolotlMessage message);
+}
diff --git a/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/AxolotlServiceImpl.java b/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/AxolotlServiceImpl.java
new file mode 100644
index 00000000..5a05b34c
--- /dev/null
+++ b/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/AxolotlServiceImpl.java
@@ -0,0 +1,1021 @@
+package de.thedevstack.conversationsplus.crypto.axolotl;
+
+import android.os.Bundle;
+import android.security.KeyChain;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.util.Log;
+import android.util.Pair;
+
+import org.bouncycastle.jce.provider.BouncyCastleProvider;
+import org.whispersystems.libaxolotl.AxolotlAddress;
+import org.whispersystems.libaxolotl.IdentityKey;
+import org.whispersystems.libaxolotl.IdentityKeyPair;
+import org.whispersystems.libaxolotl.InvalidKeyException;
+import org.whispersystems.libaxolotl.InvalidKeyIdException;
+import org.whispersystems.libaxolotl.SessionBuilder;
+import org.whispersystems.libaxolotl.UntrustedIdentityException;
+import org.whispersystems.libaxolotl.ecc.ECPublicKey;
+import org.whispersystems.libaxolotl.state.PreKeyBundle;
+import org.whispersystems.libaxolotl.state.PreKeyRecord;
+import org.whispersystems.libaxolotl.state.SignedPreKeyRecord;
+import org.whispersystems.libaxolotl.util.KeyHelper;
+
+import java.security.PrivateKey;
+import java.security.Security;
+import java.security.Signature;
+import java.security.cert.X509Certificate;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Random;
+import java.util.Set;
+
+import de.thedevstack.conversationsplus.Config;
+import de.thedevstack.conversationsplus.entities.Account;
+import de.thedevstack.conversationsplus.entities.Contact;
+import de.thedevstack.conversationsplus.entities.Conversation;
+import de.thedevstack.conversationsplus.entities.Message;
+import de.thedevstack.conversationsplus.parser.IqParser;
+import de.thedevstack.conversationsplus.services.XmppConnectionService;
+import de.thedevstack.conversationsplus.utils.CryptoHelper;
+import de.thedevstack.conversationsplus.utils.SerialSingleThreadExecutor;
+import de.thedevstack.conversationsplus.xml.Element;
+import de.thedevstack.conversationsplus.xmpp.OnIqPacketReceived;
+import de.thedevstack.conversationsplus.xmpp.jid.InvalidJidException;
+import de.thedevstack.conversationsplus.xmpp.jid.Jid;
+import de.thedevstack.conversationsplus.xmpp.stanzas.IqPacket;
+
+public class AxolotlServiceImpl implements AxolotlService {
+
+	public static final int NUM_KEYS_TO_PUBLISH = 100;
+	public static final int publishTriesThreshold = 3;
+
+	private final Account account;
+	private final XmppConnectionService mXmppConnectionService;
+	private final SQLiteAxolotlStore axolotlStore;
+	private final SessionMap sessions;
+	private final Map<Jid, Set<Integer>> deviceIds;
+	private final Map<String, XmppAxolotlMessage> messageCache;
+	private final FetchStatusMap fetchStatusMap;
+	private final SerialSingleThreadExecutor executor;
+	private int numPublishTriesOnEmptyPep = 0;
+	private boolean pepBroken = false;
+
+	@Override
+	public void onAdvancedStreamFeaturesAvailable(Account account) {
+		if (account.getXmppConnection() != null && account.getXmppConnection().getFeatures().pep()) {
+			publishBundlesIfNeeded(true, false);
+		} else {
+			Log.d(Config.LOGTAG,account.getJid().toBareJid()+": skipping OMEMO initialization");
+		}
+	}
+
+	@Override
+	public boolean fetchMapHasErrors(Contact contact) {
+		Jid jid = contact.getJid().toBareJid();
+		if (deviceIds.get(jid) != null) {
+			for (Integer foreignId : this.deviceIds.get(jid)) {
+				AxolotlAddress address = new AxolotlAddress(jid.toString(), foreignId);
+				if (fetchStatusMap.getAll(address).containsValue(FetchStatus.ERROR)) {
+					return true;
+				}
+			}
+		}
+		return false;
+	}
+
+	private static class AxolotlAddressMap<T> {
+		protected Map<String, Map<Integer, T>> map;
+		protected final Object MAP_LOCK = new Object();
+
+		public AxolotlAddressMap() {
+			this.map = new HashMap<>();
+		}
+
+		public void put(AxolotlAddress address, T value) {
+			synchronized (MAP_LOCK) {
+				Map<Integer, T> devices = map.get(address.getName());
+				if (devices == null) {
+					devices = new HashMap<>();
+					map.put(address.getName(), devices);
+				}
+				devices.put(address.getDeviceId(), value);
+			}
+		}
+
+		public T get(AxolotlAddress address) {
+			synchronized (MAP_LOCK) {
+				Map<Integer, T> devices = map.get(address.getName());
+				if (devices == null) {
+					return null;
+				}
+				return devices.get(address.getDeviceId());
+			}
+		}
+
+		public Map<Integer, T> getAll(AxolotlAddress address) {
+			synchronized (MAP_LOCK) {
+				Map<Integer, T> devices = map.get(address.getName());
+				if (devices == null) {
+					return new HashMap<>();
+				}
+				return devices;
+			}
+		}
+
+		public boolean hasAny(AxolotlAddress address) {
+			synchronized (MAP_LOCK) {
+				Map<Integer, T> devices = map.get(address.getName());
+				return devices != null && !devices.isEmpty();
+			}
+		}
+
+		public void clear() {
+			map.clear();
+		}
+
+	}
+
+	private static class SessionMap extends AxolotlAddressMap<XmppAxolotlSession> {
+		private final XmppConnectionService xmppConnectionService;
+		private final Account account;
+
+		public SessionMap(XmppConnectionService service, SQLiteAxolotlStore store, Account account) {
+			super();
+			this.xmppConnectionService = service;
+			this.account = account;
+			this.fillMap(store);
+		}
+
+		private void putDevicesForJid(String bareJid, List<Integer> deviceIds, SQLiteAxolotlStore store) {
+			for (Integer deviceId : deviceIds) {
+				AxolotlAddress axolotlAddress = new AxolotlAddress(bareJid, deviceId);
+				Log.d(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Building session for remote address: " + axolotlAddress.toString());
+				IdentityKey identityKey = store.loadSession(axolotlAddress).getSessionState().getRemoteIdentityKey();
+				if(Config.X509_VERIFICATION) {
+					X509Certificate certificate = store.getFingerprintCertificate(identityKey.getFingerprint().replaceAll("\\s", ""));
+					if (certificate != null) {
+						Bundle information = CryptoHelper.extractCertificateInformation(certificate);
+						try {
+							final String cn = information.getString("subject_cn");
+							final Jid jid = Jid.fromString(bareJid);
+							Log.d(Config.LOGTAG,"setting common name for "+jid+" to "+cn);
+							account.getRoster().getContact(jid).setCommonName(cn);
+						} catch (final InvalidJidException ignored) {
+							//ignored
+						}
+					}
+				}
+				this.put(axolotlAddress, new XmppAxolotlSession(account, store, axolotlAddress, identityKey));
+			}
+		}
+
+		private void fillMap(SQLiteAxolotlStore store) {
+			List<Integer> deviceIds = store.getSubDeviceSessions(account.getJid().toBareJid().toString());
+			putDevicesForJid(account.getJid().toBareJid().toString(), deviceIds, store);
+			for (Contact contact : account.getRoster().getContacts()) {
+				Jid bareJid = contact.getJid().toBareJid();
+				String address = bareJid.toString();
+				deviceIds = store.getSubDeviceSessions(address);
+				putDevicesForJid(address, deviceIds, store);
+			}
+
+		}
+
+		@Override
+		public void put(AxolotlAddress address, XmppAxolotlSession value) {
+			super.put(address, value);
+			value.setNotFresh();
+			xmppConnectionService.syncRosterToDisk(account);
+		}
+
+		public void put(XmppAxolotlSession session) {
+			this.put(session.getRemoteAddress(), session);
+		}
+	}
+
+	private static class FetchStatusMap extends AxolotlAddressMap<FetchStatus> {
+
+	}
+
+	public static String getLogprefix(Account account) {
+		return LOGPREFIX + " (" + account.getJid().toBareJid().toString() + "): ";
+	}
+
+	public AxolotlServiceImpl(Account account, XmppConnectionService connectionService) {
+		if (Security.getProvider("BC") == null) {
+			Security.addProvider(new BouncyCastleProvider());
+		}
+		this.mXmppConnectionService = connectionService;
+		this.account = account;
+		this.axolotlStore = new SQLiteAxolotlStore(this.account, this.mXmppConnectionService);
+		this.deviceIds = new HashMap<>();
+		this.messageCache = new HashMap<>();
+		this.sessions = new SessionMap(mXmppConnectionService, axolotlStore, account);
+		this.fetchStatusMap = new FetchStatusMap();
+		this.executor = new SerialSingleThreadExecutor();
+	}
+
+	@Override
+	public String getOwnFingerprint() {
+		return axolotlStore.getIdentityKeyPair().getPublicKey().getFingerprint().replaceAll("\\s", "");
+	}
+
+	@Override
+	public Set<IdentityKey> getKeysWithTrust(XmppAxolotlSession.Trust trust) {
+		return axolotlStore.getContactKeysWithTrust(account.getJid().toBareJid().toString(), trust);
+	}
+
+	@Override
+	public Set<IdentityKey> getKeysWithTrust(XmppAxolotlSession.Trust trust, Contact contact) {
+		return axolotlStore.getContactKeysWithTrust(contact.getJid().toBareJid().toString(), trust);
+	}
+
+	@Override
+	public long getNumTrustedKeys(Contact contact) {
+		return axolotlStore.getContactNumTrustedKeys(contact.getJid().toBareJid().toString());
+	}
+
+	private AxolotlAddress getAddressForJid(Jid jid) {
+		return new AxolotlAddress(jid.toString(), 0);
+	}
+
+	private Set<XmppAxolotlSession> findOwnSessions() {
+		AxolotlAddress ownAddress = getAddressForJid(account.getJid().toBareJid());
+		return new HashSet<>(this.sessions.getAll(ownAddress).values());
+	}
+
+	private Set<XmppAxolotlSession> findSessionsforContact(Contact contact) {
+		AxolotlAddress contactAddress = getAddressForJid(contact.getJid());
+		return new HashSet<>(this.sessions.getAll(contactAddress).values());
+	}
+
+	@Override
+	public Set<String> getFingerprintsForOwnSessions() {
+		Set<String> fingerprints = new HashSet<>();
+		for (XmppAxolotlSession session : findOwnSessions()) {
+			fingerprints.add(session.getFingerprint());
+		}
+		return fingerprints;
+	}
+
+	@Override
+	public Set<String> getFingerprintsForContact(final Contact contact) {
+		Set<String> fingerprints = new HashSet<>();
+		for (XmppAxolotlSession session : findSessionsforContact(contact)) {
+			fingerprints.add(session.getFingerprint());
+		}
+		return fingerprints;
+	}
+
+	private boolean hasAny(Contact contact) {
+		AxolotlAddress contactAddress = getAddressForJid(contact.getJid());
+		return sessions.hasAny(contactAddress);
+	}
+
+	@Override
+	public boolean isPepBroken() {
+		return this.pepBroken;
+	}
+
+	@Override
+	public void regenerateKeys(boolean wipeOther) {
+		axolotlStore.regenerate();
+		sessions.clear();
+		fetchStatusMap.clear();
+		publishBundlesIfNeeded(true, wipeOther);
+	}
+
+	@Override
+	public int getOwnDeviceId() {
+		return axolotlStore.getLocalRegistrationId();
+	}
+
+	@Override
+	public Set<Integer> getOwnDeviceIds() {
+		return this.deviceIds.get(account.getJid().toBareJid());
+	}
+
+	private void setTrustOnSessions(final Jid jid, @NonNull final Set<Integer> deviceIds,
+	                                final XmppAxolotlSession.Trust from,
+	                                final XmppAxolotlSession.Trust to) {
+		for (Integer deviceId : deviceIds) {
+			AxolotlAddress address = new AxolotlAddress(jid.toBareJid().toString(), deviceId);
+			XmppAxolotlSession session = sessions.get(address);
+			if (session != null && session.getFingerprint() != null
+					&& session.getTrust() == from) {
+				session.setTrust(to);
+			}
+		}
+	}
+
+	@Override
+	public void registerDevices(final Jid jid, @NonNull final Set<Integer> deviceIds) {
+		if (jid.toBareJid().equals(account.getJid().toBareJid())) {
+			if (!deviceIds.isEmpty()) {
+				Log.d(Config.LOGTAG, getLogprefix(account) + "Received non-empty own device list. Resetting publish attemps and pepBroken status.");
+				pepBroken = false;
+				numPublishTriesOnEmptyPep = 0;
+			}
+			if (deviceIds.contains(getOwnDeviceId())) {
+				deviceIds.remove(getOwnDeviceId());
+			} else {
+				publishOwnDeviceId(deviceIds);
+			}
+			for (Integer deviceId : deviceIds) {
+				AxolotlAddress ownDeviceAddress = new AxolotlAddress(jid.toBareJid().toString(), deviceId);
+				if (sessions.get(ownDeviceAddress) == null) {
+					buildSessionFromPEP(ownDeviceAddress);
+				}
+			}
+		}
+		Set<Integer> expiredDevices = new HashSet<>(axolotlStore.getSubDeviceSessions(jid.toBareJid().toString()));
+		expiredDevices.removeAll(deviceIds);
+		setTrustOnSessions(jid, expiredDevices, XmppAxolotlSession.Trust.TRUSTED,
+				XmppAxolotlSession.Trust.INACTIVE_TRUSTED);
+		setTrustOnSessions(jid, expiredDevices, XmppAxolotlSession.Trust.TRUSTED_X509,
+				XmppAxolotlSession.Trust.INACTIVE_TRUSTED_X509);
+		setTrustOnSessions(jid, expiredDevices, XmppAxolotlSession.Trust.UNDECIDED,
+				XmppAxolotlSession.Trust.INACTIVE_UNDECIDED);
+		setTrustOnSessions(jid, expiredDevices, XmppAxolotlSession.Trust.UNTRUSTED,
+				XmppAxolotlSession.Trust.INACTIVE_UNTRUSTED);
+		Set<Integer> newDevices = new HashSet<>(deviceIds);
+		setTrustOnSessions(jid, newDevices, XmppAxolotlSession.Trust.INACTIVE_TRUSTED,
+				XmppAxolotlSession.Trust.TRUSTED);
+		setTrustOnSessions(jid, newDevices, XmppAxolotlSession.Trust.INACTIVE_TRUSTED_X509,
+				XmppAxolotlSession.Trust.TRUSTED_X509);
+		setTrustOnSessions(jid, newDevices, XmppAxolotlSession.Trust.INACTIVE_UNDECIDED,
+				XmppAxolotlSession.Trust.UNDECIDED);
+		setTrustOnSessions(jid, newDevices, XmppAxolotlSession.Trust.INACTIVE_UNTRUSTED,
+				XmppAxolotlSession.Trust.UNTRUSTED);
+		this.deviceIds.put(jid, deviceIds);
+		mXmppConnectionService.keyStatusUpdated(null);
+	}
+
+	@Override
+	public void wipeOtherPepDevices() {
+		if (pepBroken) {
+			Log.d(Config.LOGTAG, getLogprefix(account) + "wipeOtherPepDevices called, but PEP is broken. Ignoring... ");
+			return;
+		}
+		Set<Integer> deviceIds = new HashSet<>();
+		deviceIds.add(getOwnDeviceId());
+		IqPacket publish = mXmppConnectionService.getIqGenerator().publishDeviceIds(deviceIds);
+		Log.d(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Wiping all other devices from Pep:" + publish);
+		mXmppConnectionService.sendIqPacket(account, publish, new OnIqPacketReceived() {
+			@Override
+			public void onIqPacketReceived(Account account, IqPacket packet) {
+				// TODO: implement this!
+			}
+		});
+	}
+
+	@Override
+	public void purgeKey(final String fingerprint) {
+		axolotlStore.setFingerprintTrust(fingerprint.replaceAll("\\s", ""), XmppAxolotlSession.Trust.COMPROMISED);
+	}
+
+	@Override
+	public void publishOwnDeviceIdIfNeeded() {
+		if (pepBroken) {
+			Log.d(Config.LOGTAG, getLogprefix(account) + "publishOwnDeviceIdIfNeeded called, but PEP is broken. Ignoring... ");
+			return;
+		}
+		IqPacket packet = mXmppConnectionService.getIqGenerator().retrieveDeviceIds(account.getJid().toBareJid());
+		mXmppConnectionService.sendIqPacket(account, packet, new OnIqPacketReceived() {
+			@Override
+			public void onIqPacketReceived(Account account, IqPacket packet) {
+				if (packet.getType() == IqPacket.TYPE.TIMEOUT) {
+					Log.d(Config.LOGTAG, getLogprefix(account) + "Timeout received while retrieving own Device Ids.");
+				} else {
+					Element item = mXmppConnectionService.getIqParser().getItem(packet);
+					Set<Integer> deviceIds = mXmppConnectionService.getIqParser().deviceIds(item);
+					if (!deviceIds.contains(getOwnDeviceId())) {
+						publishOwnDeviceId(deviceIds);
+					}
+				}
+			}
+		});
+	}
+
+	@Override
+	public void publishOwnDeviceId(Set<Integer> deviceIds) {
+		Set<Integer> deviceIdsCopy = new HashSet<>(deviceIds);
+		if (!deviceIdsCopy.contains(getOwnDeviceId())) {
+			Log.d(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Own device " + getOwnDeviceId() + " not in PEP devicelist.");
+			if (deviceIdsCopy.isEmpty()) {
+				if (numPublishTriesOnEmptyPep >= publishTriesThreshold) {
+					Log.w(Config.LOGTAG, getLogprefix(account) + "Own device publish attempt threshold exceeded, aborting...");
+					pepBroken = true;
+					return;
+				} else {
+					numPublishTriesOnEmptyPep++;
+					Log.w(Config.LOGTAG, getLogprefix(account) + "Own device list empty, attempting to publish (try " + numPublishTriesOnEmptyPep + ")");
+				}
+			} else {
+				numPublishTriesOnEmptyPep = 0;
+			}
+			deviceIdsCopy.add(getOwnDeviceId());
+			IqPacket publish = mXmppConnectionService.getIqGenerator().publishDeviceIds(deviceIdsCopy);
+			mXmppConnectionService.sendIqPacket(account, publish, new OnIqPacketReceived() {
+				@Override
+				public void onIqPacketReceived(Account account, IqPacket packet) {
+					if (packet.getType() != IqPacket.TYPE.RESULT) {
+						Log.d(Config.LOGTAG, getLogprefix(account) + "Error received while publishing own device id" + packet.findChild("error"));
+					}
+				}
+			});
+		}
+	}
+
+	@Override
+	public void publishDeviceVerificationAndBundle(final SignedPreKeyRecord signedPreKeyRecord,
+												   final Set<PreKeyRecord> preKeyRecords,
+												   final boolean announceAfter,
+												   final boolean wipe) {
+		try {
+			IdentityKey axolotlPublicKey = axolotlStore.getIdentityKeyPair().getPublicKey();
+			PrivateKey x509PrivateKey = KeyChain.getPrivateKey(mXmppConnectionService, account.getPrivateKeyAlias());
+			X509Certificate[] chain = KeyChain.getCertificateChain(mXmppConnectionService, account.getPrivateKeyAlias());
+			Signature verifier = Signature.getInstance("sha256WithRSA");
+			verifier.initSign(x509PrivateKey,mXmppConnectionService.getRNG());
+			verifier.update(axolotlPublicKey.serialize());
+			byte[] signature = verifier.sign();
+			IqPacket packet = mXmppConnectionService.getIqGenerator().publishVerification(signature, chain, getOwnDeviceId());
+			Log.d(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + ": publish verification for device "+getOwnDeviceId());
+			mXmppConnectionService.sendIqPacket(account, packet, new OnIqPacketReceived() {
+				@Override
+				public void onIqPacketReceived(Account account, IqPacket packet) {
+					publishDeviceBundle(signedPreKeyRecord, preKeyRecords, announceAfter, wipe);
+				}
+			});
+		} catch (Exception  e) {
+			e.printStackTrace();
+		}
+	}
+
+	@Override
+	public void publishBundlesIfNeeded(final boolean announce, final boolean wipe) {
+		if (pepBroken) {
+			Log.d(Config.LOGTAG, getLogprefix(account) + "publishBundlesIfNeeded called, but PEP is broken. Ignoring... ");
+			return;
+		}
+		IqPacket packet = mXmppConnectionService.getIqGenerator().retrieveBundlesForDevice(account.getJid().toBareJid(), getOwnDeviceId());
+		mXmppConnectionService.sendIqPacket(account, packet, new OnIqPacketReceived() {
+			@Override
+			public void onIqPacketReceived(Account account, IqPacket packet) {
+
+				if (packet.getType() == IqPacket.TYPE.TIMEOUT) {
+					return; //ignore timeout. do nothing
+				}
+
+				if (packet.getType() == IqPacket.TYPE.ERROR) {
+					Element error = packet.findChild("error");
+					if (error == null || !error.hasChild("item-not-found")) {
+						pepBroken = true;
+						Log.w(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "request for device bundles came back with something other than item-not-found" + packet);
+						return;
+					}
+				}
+
+				PreKeyBundle bundle = mXmppConnectionService.getIqParser().bundle(packet);
+				Map<Integer, ECPublicKey> keys = mXmppConnectionService.getIqParser().preKeyPublics(packet);
+				boolean flush = false;
+				if (bundle == null) {
+					Log.w(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Received invalid bundle:" + packet);
+					bundle = new PreKeyBundle(-1, -1, -1, null, -1, null, null, null);
+					flush = true;
+				}
+				if (keys == null) {
+					Log.w(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Received invalid prekeys:" + packet);
+				}
+				try {
+					boolean changed = false;
+					// Validate IdentityKey
+					IdentityKeyPair identityKeyPair = axolotlStore.getIdentityKeyPair();
+					if (flush || !identityKeyPair.getPublicKey().equals(bundle.getIdentityKey())) {
+						Log.i(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Adding own IdentityKey " + identityKeyPair.getPublicKey() + " to PEP.");
+						changed = true;
+					}
+
+					// Validate signedPreKeyRecord + ID
+					SignedPreKeyRecord signedPreKeyRecord;
+					int numSignedPreKeys = axolotlStore.loadSignedPreKeys().size();
+					try {
+						signedPreKeyRecord = axolotlStore.loadSignedPreKey(bundle.getSignedPreKeyId());
+						if (flush
+								|| !bundle.getSignedPreKey().equals(signedPreKeyRecord.getKeyPair().getPublicKey())
+								|| !Arrays.equals(bundle.getSignedPreKeySignature(), signedPreKeyRecord.getSignature())) {
+							Log.i(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Adding new signedPreKey with ID " + (numSignedPreKeys + 1) + " to PEP.");
+							signedPreKeyRecord = KeyHelper.generateSignedPreKey(identityKeyPair, numSignedPreKeys + 1);
+							axolotlStore.storeSignedPreKey(signedPreKeyRecord.getId(), signedPreKeyRecord);
+							changed = true;
+						}
+					} catch (InvalidKeyIdException e) {
+						Log.i(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Adding new signedPreKey with ID " + (numSignedPreKeys + 1) + " to PEP.");
+						signedPreKeyRecord = KeyHelper.generateSignedPreKey(identityKeyPair, numSignedPreKeys + 1);
+						axolotlStore.storeSignedPreKey(signedPreKeyRecord.getId(), signedPreKeyRecord);
+						changed = true;
+					}
+
+					// Validate PreKeys
+					Set<PreKeyRecord> preKeyRecords = new HashSet<>();
+					if (keys != null) {
+						for (Integer id : keys.keySet()) {
+							try {
+								PreKeyRecord preKeyRecord = axolotlStore.loadPreKey(id);
+								if (preKeyRecord.getKeyPair().getPublicKey().equals(keys.get(id))) {
+									preKeyRecords.add(preKeyRecord);
+								}
+							} catch (InvalidKeyIdException ignored) {
+							}
+						}
+					}
+					int newKeys = NUM_KEYS_TO_PUBLISH - preKeyRecords.size();
+					if (newKeys > 0) {
+						List<PreKeyRecord> newRecords = KeyHelper.generatePreKeys(
+								axolotlStore.getCurrentPreKeyId() + 1, newKeys);
+						preKeyRecords.addAll(newRecords);
+						for (PreKeyRecord record : newRecords) {
+							axolotlStore.storePreKey(record.getId(), record);
+						}
+						changed = true;
+						Log.i(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Adding " + newKeys + " new preKeys to PEP.");
+					}
+
+
+					if (changed) {
+						if (account.getPrivateKeyAlias() != null && Config.X509_VERIFICATION) {
+							mXmppConnectionService.publishDisplayName(account);
+							publishDeviceVerificationAndBundle(signedPreKeyRecord, preKeyRecords, announce, wipe);
+						} else {
+							publishDeviceBundle(signedPreKeyRecord, preKeyRecords, announce, wipe);
+						}
+					} else {
+						Log.d(Config.LOGTAG, getLogprefix(account) + "Bundle " + getOwnDeviceId() + " in PEP was current");
+						if (wipe) {
+							wipeOtherPepDevices();
+						} else if (announce) {
+							Log.d(Config.LOGTAG, getLogprefix(account) + "Announcing device " + getOwnDeviceId());
+							publishOwnDeviceIdIfNeeded();
+						}
+					}
+				} catch (InvalidKeyException e) {
+					Log.e(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Failed to publish bundle " + getOwnDeviceId() + ", reason: " + e.getMessage());
+				}
+			}
+		});
+	}
+
+	private void publishDeviceBundle(SignedPreKeyRecord signedPreKeyRecord,
+									 Set<PreKeyRecord> preKeyRecords,
+									 final boolean announceAfter,
+									 final boolean wipe) {
+		IqPacket publish = mXmppConnectionService.getIqGenerator().publishBundles(
+				signedPreKeyRecord, axolotlStore.getIdentityKeyPair().getPublicKey(),
+				preKeyRecords, getOwnDeviceId());
+		Log.d(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + ": Bundle " + getOwnDeviceId() + " in PEP not current. Publishing: " + publish);
+		mXmppConnectionService.sendIqPacket(account, publish, new OnIqPacketReceived() {
+			@Override
+			public void onIqPacketReceived(Account account, IqPacket packet) {
+				if (packet.getType() == IqPacket.TYPE.RESULT) {
+					Log.d(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Successfully published bundle. ");
+					if (wipe) {
+						wipeOtherPepDevices();
+					} else if (announceAfter) {
+						Log.d(Config.LOGTAG, getLogprefix(account) + "Announcing device " + getOwnDeviceId());
+						publishOwnDeviceIdIfNeeded();
+					}
+				} else {
+					Log.d(Config.LOGTAG, getLogprefix(account) + "Error received while publishing bundle: " + packet.findChild("error"));
+				}
+			}
+		});
+	}
+
+	@Override
+	public boolean isContactAxolotlCapable(Contact contact) {
+		Jid jid = contact.getJid().toBareJid();
+		return hasAny(contact) ||
+				(deviceIds.containsKey(jid) && !deviceIds.get(jid).isEmpty());
+	}
+
+	@Override
+	public XmppAxolotlSession.Trust getFingerprintTrust(String fingerprint) {
+		return axolotlStore.getFingerprintTrust(fingerprint);
+	}
+
+	@Override
+	public X509Certificate getFingerprintCertificate(String fingerprint) {
+		return axolotlStore.getFingerprintCertificate(fingerprint);
+	}
+
+	@Override
+	public void setFingerprintTrust(String fingerprint, XmppAxolotlSession.Trust trust) {
+		axolotlStore.setFingerprintTrust(fingerprint, trust);
+	}
+
+	private void verifySessionWithPEP(final XmppAxolotlSession session) {
+		Log.d(Config.LOGTAG, "trying to verify fresh session (" + session.getRemoteAddress().getName() + ") with pep");
+		final AxolotlAddress address = session.getRemoteAddress();
+		final IdentityKey identityKey = session.getIdentityKey();
+		try {
+			IqPacket packet = mXmppConnectionService.getIqGenerator().retrieveVerificationForDevice(Jid.fromString(address.getName()), address.getDeviceId());
+			mXmppConnectionService.sendIqPacket(account, packet, new OnIqPacketReceived() {
+				@Override
+				public void onIqPacketReceived(Account account, IqPacket packet) {
+					Pair<X509Certificate[],byte[]> verification = mXmppConnectionService.getIqParser().verification(packet);
+					if (verification != null) {
+						try {
+							Signature verifier = Signature.getInstance("sha256WithRSA");
+							verifier.initVerify(verification.first[0]);
+							verifier.update(identityKey.serialize());
+							if (verifier.verify(verification.second)) {
+								try {
+									mXmppConnectionService.getMemorizingTrustManager().getNonInteractive().checkClientTrusted(verification.first, "RSA");
+									String fingerprint = session.getFingerprint();
+									Log.d(Config.LOGTAG, "verified session with x.509 signature. fingerprint was: "+fingerprint);
+									setFingerprintTrust(fingerprint, XmppAxolotlSession.Trust.TRUSTED_X509);
+									axolotlStore.setFingerprintCertificate(fingerprint, verification.first[0]);
+									fetchStatusMap.put(address, FetchStatus.SUCCESS_VERIFIED);
+									Bundle information = CryptoHelper.extractCertificateInformation(verification.first[0]);
+									try {
+										final String cn = information.getString("subject_cn");
+										final Jid jid = Jid.fromString(address.getName());
+										Log.d(Config.LOGTAG,"setting common name for "+jid+" to "+cn);
+										account.getRoster().getContact(jid).setCommonName(cn);
+									} catch (final InvalidJidException ignored) {
+										//ignored
+									}
+									finishBuildingSessionsFromPEP(address);
+									return;
+								} catch (Exception e) {
+									Log.d(Config.LOGTAG,"could not verify certificate");
+								}
+							}
+						} catch (Exception e) {
+							Log.d(Config.LOGTAG, "error during verification " + e.getMessage());
+						}
+					} else {
+						Log.d(Config.LOGTAG,"no verification found");
+					}
+					fetchStatusMap.put(address, FetchStatus.SUCCESS);
+					finishBuildingSessionsFromPEP(address);
+				}
+			});
+		} catch (InvalidJidException e) {
+			fetchStatusMap.put(address, FetchStatus.SUCCESS);
+			finishBuildingSessionsFromPEP(address);
+		}
+	}
+
+	private void finishBuildingSessionsFromPEP(final AxolotlAddress address) {
+		AxolotlAddress ownAddress = new AxolotlAddress(account.getJid().toBareJid().toString(), 0);
+		if (!fetchStatusMap.getAll(ownAddress).containsValue(FetchStatus.PENDING)
+				&& !fetchStatusMap.getAll(address).containsValue(FetchStatus.PENDING)) {
+			FetchStatus report = null;
+			if (fetchStatusMap.getAll(ownAddress).containsValue(FetchStatus.SUCCESS_VERIFIED)
+					| fetchStatusMap.getAll(address).containsValue(FetchStatus.SUCCESS_VERIFIED)) {
+				report = FetchStatus.SUCCESS_VERIFIED;
+			} else if (fetchStatusMap.getAll(ownAddress).containsValue(FetchStatus.ERROR)
+					|| fetchStatusMap.getAll(address).containsValue(FetchStatus.ERROR)) {
+				report = FetchStatus.ERROR;
+			}
+			mXmppConnectionService.keyStatusUpdated(report);
+		}
+	}
+
+	private void buildSessionFromPEP(final AxolotlAddress address) {
+		Log.i(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Building new sesstion for " + address.toString());
+		if (address.getDeviceId() == getOwnDeviceId()) {
+			throw new AssertionError("We should NEVER build a session with ourselves. What happened here?!");
+		}
+
+		try {
+			IqPacket bundlesPacket = mXmppConnectionService.getIqGenerator().retrieveBundlesForDevice(
+					Jid.fromString(address.getName()), address.getDeviceId());
+			Log.d(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Retrieving bundle: " + bundlesPacket);
+			mXmppConnectionService.sendIqPacket(account, bundlesPacket, new OnIqPacketReceived() {
+
+				@Override
+				public void onIqPacketReceived(Account account, IqPacket packet) {
+					if (packet.getType() == IqPacket.TYPE.TIMEOUT) {
+						fetchStatusMap.put(address, FetchStatus.TIMEOUT);
+					} else if (packet.getType() == IqPacket.TYPE.RESULT) {
+						Log.d(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Received preKey IQ packet, processing...");
+						final IqParser parser = mXmppConnectionService.getIqParser();
+						final List<PreKeyBundle> preKeyBundleList = parser.preKeys(packet);
+						final PreKeyBundle bundle = parser.bundle(packet);
+						if (preKeyBundleList.isEmpty() || bundle == null) {
+							Log.e(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "preKey IQ packet invalid: " + packet);
+							fetchStatusMap.put(address, FetchStatus.ERROR);
+							finishBuildingSessionsFromPEP(address);
+							return;
+						}
+						Random random = new Random();
+						final PreKeyBundle preKey = preKeyBundleList.get(random.nextInt(preKeyBundleList.size()));
+						if (preKey == null) {
+							//should never happen
+							fetchStatusMap.put(address, FetchStatus.ERROR);
+							finishBuildingSessionsFromPEP(address);
+							return;
+						}
+
+						final PreKeyBundle preKeyBundle = new PreKeyBundle(0, address.getDeviceId(),
+								preKey.getPreKeyId(), preKey.getPreKey(),
+								bundle.getSignedPreKeyId(), bundle.getSignedPreKey(),
+								bundle.getSignedPreKeySignature(), bundle.getIdentityKey());
+
+						try {
+							SessionBuilder builder = new SessionBuilder(axolotlStore, address);
+							builder.process(preKeyBundle);
+							XmppAxolotlSession session = new XmppAxolotlSession(account, axolotlStore, address, bundle.getIdentityKey());
+							sessions.put(address, session);
+							if (Config.X509_VERIFICATION) {
+								verifySessionWithPEP(session);
+							} else {
+								fetchStatusMap.put(address, FetchStatus.SUCCESS);
+								finishBuildingSessionsFromPEP(address);
+							}
+						} catch (UntrustedIdentityException | InvalidKeyException e) {
+							Log.e(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Error building session for " + address + ": "
+									+ e.getClass().getName() + ", " + e.getMessage());
+							fetchStatusMap.put(address, FetchStatus.ERROR);
+							finishBuildingSessionsFromPEP(address);
+						}
+					} else {
+						fetchStatusMap.put(address, FetchStatus.ERROR);
+						Log.d(Config.LOGTAG, getLogprefix(account) + "Error received while building session:" + packet.findChild("error"));
+						finishBuildingSessionsFromPEP(address);
+					}
+				}
+			});
+		} catch (InvalidJidException e) {
+			Log.e(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Got address with invalid jid: " + address.getName());
+		}
+	}
+
+	@Override
+	public Set<AxolotlAddress> findDevicesWithoutSession(final Conversation conversation) {
+		return findDevicesWithoutSession(conversation.getContact().getJid().toBareJid());
+	}
+
+	@Override
+	public Set<AxolotlAddress> findDevicesWithoutSession(final Jid contactJid) {
+		Log.d(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Finding devices without session for " + contactJid);
+		Set<AxolotlAddress> addresses = new HashSet<>();
+		if (deviceIds.get(contactJid) != null) {
+			for (Integer foreignId : this.deviceIds.get(contactJid)) {
+				AxolotlAddress address = new AxolotlAddress(contactJid.toString(), foreignId);
+				if (sessions.get(address) == null) {
+					IdentityKey identityKey = axolotlStore.loadSession(address).getSessionState().getRemoteIdentityKey();
+					if (identityKey != null) {
+						Log.d(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Already have session for " + address.toString() + ", adding to cache...");
+						XmppAxolotlSession session = new XmppAxolotlSession(account, axolotlStore, address, identityKey);
+						sessions.put(address, session);
+					} else {
+						Log.d(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Found device " + contactJid + ":" + foreignId);
+						if (fetchStatusMap.get(address) != FetchStatus.ERROR) {
+							addresses.add(address);
+						} else {
+							Log.d(Config.LOGTAG,getLogprefix(account)+"skipping over "+address+" because it's broken");
+						}
+					}
+				}
+			}
+		} else {
+			Log.w(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Have no target devices in PEP!");
+		}
+		if (deviceIds.get(account.getJid().toBareJid()) != null) {
+			for (Integer ownId : this.deviceIds.get(account.getJid().toBareJid())) {
+				AxolotlAddress address = new AxolotlAddress(account.getJid().toBareJid().toString(), ownId);
+				if (sessions.get(address) == null) {
+					IdentityKey identityKey = axolotlStore.loadSession(address).getSessionState().getRemoteIdentityKey();
+					if (identityKey != null) {
+						Log.d(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Already have session for " + address.toString() + ", adding to cache...");
+						XmppAxolotlSession session = new XmppAxolotlSession(account, axolotlStore, address, identityKey);
+						sessions.put(address, session);
+					} else {
+						Log.d(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Found device " + account.getJid().toBareJid() + ":" + ownId);
+						if (fetchStatusMap.get(address) != FetchStatus.ERROR) {
+							addresses.add(address);
+						} else {
+							Log.d(Config.LOGTAG,getLogprefix(account)+"skipping over "+address+" because it's broken");
+						}
+					}
+				}
+			}
+		}
+
+		return addresses;
+	}
+
+	@Override
+	public boolean createSessionsIfNeeded(final Conversation conversation) {
+		Log.i(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Creating axolotl sessions if needed...");
+		boolean newSessions = false;
+		Set<AxolotlAddress> addresses = findDevicesWithoutSession(conversation);
+		for (AxolotlAddress address : addresses) {
+			Log.d(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Processing device: " + address.toString());
+			FetchStatus status = fetchStatusMap.get(address);
+			if (status == null || status == FetchStatus.TIMEOUT) {
+				fetchStatusMap.put(address, FetchStatus.PENDING);
+				this.buildSessionFromPEP(address);
+				newSessions = true;
+			} else if (status == FetchStatus.PENDING) {
+				newSessions = true;
+			} else {
+				Log.d(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Already fetching bundle for " + address.toString());
+			}
+		}
+
+		return newSessions;
+	}
+
+	@Override
+	public boolean trustedSessionVerified(final Conversation conversation) {
+		Set<XmppAxolotlSession> sessions = findSessionsforContact(conversation.getContact());
+		sessions.addAll(findOwnSessions());
+		boolean verified = false;
+		for(XmppAxolotlSession session : sessions) {
+			if (session.getTrust().trusted()) {
+				if (session.getTrust() == XmppAxolotlSession.Trust.TRUSTED_X509) {
+					verified = true;
+				} else {
+					return false;
+				}
+			}
+		}
+		return verified;
+	}
+
+	@Override
+	public boolean hasPendingKeyFetches(Account account, Contact contact) {
+		AxolotlAddress ownAddress = new AxolotlAddress(account.getJid().toBareJid().toString(), 0);
+		AxolotlAddress foreignAddress = new AxolotlAddress(contact.getJid().toBareJid().toString(), 0);
+		return fetchStatusMap.getAll(ownAddress).containsValue(FetchStatus.PENDING)
+				|| fetchStatusMap.getAll(foreignAddress).containsValue(FetchStatus.PENDING);
+
+	}
+
+	@Nullable
+	private XmppAxolotlMessage buildHeader(Contact contact) {
+		final XmppAxolotlMessage axolotlMessage = new XmppAxolotlMessage(
+				contact.getJid().toBareJid(), getOwnDeviceId());
+
+		Set<XmppAxolotlSession> contactSessions = findSessionsforContact(contact);
+		Set<XmppAxolotlSession> ownSessions = findOwnSessions();
+		if (contactSessions.isEmpty()) {
+			return null;
+		}
+		Log.d(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Building axolotl foreign keyElements...");
+		for (XmppAxolotlSession session : contactSessions) {
+			Log.v(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + session.getRemoteAddress().toString());
+			axolotlMessage.addDevice(session);
+		}
+		Log.d(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Building axolotl own keyElements...");
+		for (XmppAxolotlSession session : ownSessions) {
+			Log.v(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + session.getRemoteAddress().toString());
+			axolotlMessage.addDevice(session);
+		}
+
+		return axolotlMessage;
+	}
+
+	@Override
+	@Nullable
+	public XmppAxolotlMessage encrypt(Message message) {
+		XmppAxolotlMessage axolotlMessage = buildHeader(message.getContact());
+
+		if (axolotlMessage != null) {
+			final String content;
+			if (message.hasFileOnRemoteHost()) {
+				content = message.getFileParams().url.toString();
+			} else {
+				content = message.getBody();
+			}
+			try {
+				axolotlMessage.encrypt(content);
+			} catch (CryptoFailedException e) {
+				Log.w(Config.LOGTAG, getLogprefix(account) + "Failed to encrypt message: " + e.getMessage());
+				return null;
+			}
+		}
+
+		return axolotlMessage;
+	}
+
+	@Override
+	public void preparePayloadMessage(final Message message, final boolean delay) {
+		executor.execute(new Runnable() {
+			@Override
+			public void run() {
+				XmppAxolotlMessage axolotlMessage = encrypt(message);
+				if (axolotlMessage == null) {
+					mXmppConnectionService.markMessage(message, Message.STATUS_SEND_FAILED);
+					//mXmppConnectionService.updateConversationUi();
+				} else {
+					Log.d(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Generated message, caching: " + message.getUuid());
+					messageCache.put(message.getUuid(), axolotlMessage);
+					mXmppConnectionService.resendMessage(message, delay);
+				}
+			}
+		});
+	}
+
+	@Override
+	public void prepareKeyTransportMessage(final Contact contact, final OnMessageCreatedCallback onMessageCreatedCallback) {
+		executor.execute(new Runnable() {
+			@Override
+			public void run() {
+				XmppAxolotlMessage axolotlMessage = buildHeader(contact);
+				onMessageCreatedCallback.run(axolotlMessage);
+			}
+		});
+	}
+
+	@Override
+	public XmppAxolotlMessage fetchAxolotlMessageFromCache(Message message) {
+		XmppAxolotlMessage axolotlMessage = messageCache.get(message.getUuid());
+		if (axolotlMessage != null) {
+			Log.d(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Cache hit: " + message.getUuid());
+			messageCache.remove(message.getUuid());
+		} else {
+			Log.d(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Cache miss: " + message.getUuid());
+		}
+		return axolotlMessage;
+	}
+
+	private XmppAxolotlSession recreateUncachedSession(AxolotlAddress address) {
+		IdentityKey identityKey = axolotlStore.loadSession(address).getSessionState().getRemoteIdentityKey();
+		return (identityKey != null)
+				? new XmppAxolotlSession(account, axolotlStore, address, identityKey)
+				: null;
+	}
+
+	private XmppAxolotlSession getReceivingSession(XmppAxolotlMessage message) {
+		AxolotlAddress senderAddress = new AxolotlAddress(message.getFrom().toString(),
+				message.getSenderDeviceId());
+		XmppAxolotlSession session = sessions.get(senderAddress);
+		if (session == null) {
+			Log.d(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Account: " + account.getJid() + " No axolotl session found while parsing received message " + message);
+			session = recreateUncachedSession(senderAddress);
+			if (session == null) {
+				session = new XmppAxolotlSession(account, axolotlStore, senderAddress);
+			}
+		}
+		return session;
+	}
+
+	@Override
+	public XmppAxolotlMessage.XmppAxolotlPlaintextMessage processReceivingPayloadMessage(XmppAxolotlMessage message) {
+		XmppAxolotlMessage.XmppAxolotlPlaintextMessage plaintextMessage = null;
+
+		XmppAxolotlSession session = getReceivingSession(message);
+		try {
+			plaintextMessage = message.decrypt(session, getOwnDeviceId());
+			Integer preKeyId = session.getPreKeyId();
+			if (preKeyId != null) {
+				publishBundlesIfNeeded(false, false);
+				session.resetPreKeyId();
+			}
+		} catch (CryptoFailedException e) {
+			Log.w(Config.LOGTAG, getLogprefix(account) + "Failed to decrypt message: " + e.getMessage());
+		}
+
+		if (session.isFresh() && plaintextMessage != null) {
+			putFreshSession(session);
+		}
+
+		return plaintextMessage;
+	}
+
+	@Override
+	public XmppAxolotlMessage.XmppAxolotlKeyTransportMessage processReceivingKeyTransportMessage(XmppAxolotlMessage message) {
+		XmppAxolotlMessage.XmppAxolotlKeyTransportMessage keyTransportMessage;
+
+		XmppAxolotlSession session = getReceivingSession(message);
+		keyTransportMessage = message.getParameters(session, getOwnDeviceId());
+
+		if (session.isFresh() && keyTransportMessage != null) {
+			putFreshSession(session);
+		}
+
+		return keyTransportMessage;
+	}
+
+	private void putFreshSession(XmppAxolotlSession session) {
+		Log.d(Config.LOGTAG,"put fresh session");
+		sessions.put(session);
+		if (Config.X509_VERIFICATION) {
+			if (session.getIdentityKey() != null) {
+				verifySessionWithPEP(session);
+			} else {
+				Log.e(Config.LOGTAG,account.getJid().toBareJid()+": identity key was empty after reloading for x509 verification");
+			}
+		}
+	}
+}
diff --git a/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/AxolotlServiceStub.java b/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/AxolotlServiceStub.java
new file mode 100644
index 00000000..a07905ab
--- /dev/null
+++ b/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/AxolotlServiceStub.java
@@ -0,0 +1,196 @@
+package de.thedevstack.conversationsplus.crypto.axolotl;
+
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+
+import org.whispersystems.libaxolotl.AxolotlAddress;
+import org.whispersystems.libaxolotl.IdentityKey;
+import org.whispersystems.libaxolotl.state.PreKeyRecord;
+import org.whispersystems.libaxolotl.state.SignedPreKeyRecord;
+
+import java.security.cert.X509Certificate;
+import java.util.Collections;
+import java.util.Set;
+
+import de.thedevstack.conversationsplus.entities.Account;
+import de.thedevstack.conversationsplus.entities.Contact;
+import de.thedevstack.conversationsplus.entities.Conversation;
+import de.thedevstack.conversationsplus.entities.Message;
+import de.thedevstack.conversationsplus.xmpp.jid.Jid;
+
+/**
+ * Axolotl Service Stub implementation to avoid axolotl usage.
+ */
+public class AxolotlServiceStub implements AxolotlService {
+
+    @Override
+    public boolean fetchMapHasErrors(Contact contact) {
+        return false;
+    }
+
+    @Override
+    public String getOwnFingerprint() {
+        return null;
+    }
+
+    @Override
+    public Set<IdentityKey> getKeysWithTrust(XmppAxolotlSession.Trust trust) {
+        return Collections.emptySet();
+    }
+
+    @Override
+    public Set<IdentityKey> getKeysWithTrust(XmppAxolotlSession.Trust trust, Contact contact) {
+        return Collections.emptySet();
+    }
+
+    @Override
+    public long getNumTrustedKeys(Contact contact) {
+        return 0;
+    }
+
+    @Override
+    public Set<String> getFingerprintsForOwnSessions() {
+        return Collections.emptySet();
+    }
+
+    @Override
+    public Set<String> getFingerprintsForContact(Contact contact) {
+        return Collections.emptySet();
+    }
+
+    @Override
+    public boolean isPepBroken() {
+        return true;
+    }
+
+    @Override
+    public void regenerateKeys(boolean wipeOther) {
+
+    }
+
+    @Override
+    public int getOwnDeviceId() {
+        return 0;
+    }
+
+    @Override
+    public Set<Integer> getOwnDeviceIds() {
+        return Collections.emptySet();
+    }
+
+    @Override
+    public void registerDevices(Jid jid, @NonNull Set<Integer> deviceIds) {
+
+    }
+
+    @Override
+    public void wipeOtherPepDevices() {
+
+    }
+
+    @Override
+    public void purgeKey(String fingerprint) {
+
+    }
+
+    @Override
+    public void publishOwnDeviceIdIfNeeded() {
+
+    }
+
+    @Override
+    public void publishOwnDeviceId(Set<Integer> deviceIds) {
+
+    }
+
+    @Override
+    public void publishDeviceVerificationAndBundle(SignedPreKeyRecord signedPreKeyRecord, Set<PreKeyRecord> preKeyRecords, boolean announceAfter, boolean wipe) {
+
+    }
+
+    @Override
+    public void publishBundlesIfNeeded(boolean announce, boolean wipe) {
+
+    }
+
+    @Override
+    public boolean isContactAxolotlCapable(Contact contact) {
+        return false;
+    }
+
+    @Override
+    public XmppAxolotlSession.Trust getFingerprintTrust(String fingerprint) {
+        return XmppAxolotlSession.Trust.TRUSTED;
+    }
+
+    @Override
+    public X509Certificate getFingerprintCertificate(String fingerprint) {
+        return null;
+    }
+
+    @Override
+    public void setFingerprintTrust(String fingerprint, XmppAxolotlSession.Trust trust) {
+
+    }
+
+    @Override
+    public Set<AxolotlAddress> findDevicesWithoutSession(Conversation conversation) {
+        return Collections.emptySet();
+    }
+
+    @Override
+    public Set<AxolotlAddress> findDevicesWithoutSession(Jid contactJid) {
+        return Collections.emptySet();
+    }
+
+    @Override
+    public boolean createSessionsIfNeeded(Conversation conversation) {
+        return false;
+    }
+
+    @Override
+    public boolean trustedSessionVerified(Conversation conversation) {
+        return false;
+    }
+
+    @Override
+    public boolean hasPendingKeyFetches(Account account, Contact contact) {
+        return false;
+    }
+
+    @Nullable
+    @Override
+    public XmppAxolotlMessage encrypt(Message message) {
+        return null;
+    }
+
+    @Override
+    public void preparePayloadMessage(Message message, boolean delay) {
+
+    }
+
+    @Override
+    public void prepareKeyTransportMessage(Contact contact, OnMessageCreatedCallback onMessageCreatedCallback) {
+
+    }
+
+    @Override
+    public XmppAxolotlMessage fetchAxolotlMessageFromCache(Message message) {
+        return null;
+    }
+
+    @Override
+    public XmppAxolotlMessage.XmppAxolotlPlaintextMessage processReceivingPayloadMessage(XmppAxolotlMessage message) {
+        return null;
+    }
+
+    @Override
+    public XmppAxolotlMessage.XmppAxolotlKeyTransportMessage processReceivingKeyTransportMessage(XmppAxolotlMessage message) {
+        return null;
+    }
+
+    @Override
+    public void onAdvancedStreamFeaturesAvailable(Account account) {
+
+    }
+}
diff --git a/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/CryptoFailedException.java b/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/CryptoFailedException.java
new file mode 100644
index 00000000..df281248
--- /dev/null
+++ b/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/CryptoFailedException.java
@@ -0,0 +1,7 @@
+package de.thedevstack.conversationsplus.crypto.axolotl;
+
+public class CryptoFailedException extends Exception {
+	public CryptoFailedException(Exception e){
+		super(e);
+	}
+}
diff --git a/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/NoSessionsCreatedException.java b/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/NoSessionsCreatedException.java
new file mode 100644
index 00000000..bcb1c6a8
--- /dev/null
+++ b/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/NoSessionsCreatedException.java
@@ -0,0 +1,4 @@
+package de.thedevstack.conversationsplus.crypto.axolotl;
+
+public class NoSessionsCreatedException extends Throwable{
+}
diff --git a/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/OnMessageCreatedCallback.java b/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/OnMessageCreatedCallback.java
new file mode 100644
index 00000000..082b514b
--- /dev/null
+++ b/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/OnMessageCreatedCallback.java
@@ -0,0 +1,5 @@
+package de.thedevstack.conversationsplus.crypto.axolotl;
+
+public interface OnMessageCreatedCallback {
+	void run(XmppAxolotlMessage message);
+}
diff --git a/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/SQLiteAxolotlStore.java b/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/SQLiteAxolotlStore.java
new file mode 100644
index 00000000..35f630bb
--- /dev/null
+++ b/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/SQLiteAxolotlStore.java
@@ -0,0 +1,429 @@
+package de.thedevstack.conversationsplus.crypto.axolotl;
+
+import android.util.Log;
+import android.util.LruCache;
+
+import org.whispersystems.libaxolotl.AxolotlAddress;
+import org.whispersystems.libaxolotl.IdentityKey;
+import org.whispersystems.libaxolotl.IdentityKeyPair;
+import org.whispersystems.libaxolotl.InvalidKeyIdException;
+import org.whispersystems.libaxolotl.ecc.Curve;
+import org.whispersystems.libaxolotl.ecc.ECKeyPair;
+import org.whispersystems.libaxolotl.state.AxolotlStore;
+import org.whispersystems.libaxolotl.state.PreKeyRecord;
+import org.whispersystems.libaxolotl.state.SessionRecord;
+import org.whispersystems.libaxolotl.state.SignedPreKeyRecord;
+import org.whispersystems.libaxolotl.util.KeyHelper;
+
+import java.security.cert.X509Certificate;
+import java.util.List;
+import java.util.Set;
+
+import de.thedevstack.conversationsplus.Config;
+import de.thedevstack.conversationsplus.entities.Account;
+import de.thedevstack.conversationsplus.services.XmppConnectionService;
+
+public class SQLiteAxolotlStore implements AxolotlStore {
+
+	public static final String PREKEY_TABLENAME = "prekeys";
+	public static final String SIGNED_PREKEY_TABLENAME = "signed_prekeys";
+	public static final String SESSION_TABLENAME = "sessions";
+	public static final String IDENTITIES_TABLENAME = "identities";
+	public static final String ACCOUNT = "account";
+	public static final String DEVICE_ID = "device_id";
+	public static final String ID = "id";
+	public static final String KEY = "key";
+	public static final String FINGERPRINT = "fingerprint";
+	public static final String NAME = "name";
+	public static final String TRUSTED = "trusted";
+	public static final String OWN = "ownkey";
+	public static final String CERTIFICATE = "certificate";
+
+	public static final String JSONKEY_REGISTRATION_ID = "axolotl_reg_id";
+	public static final String JSONKEY_CURRENT_PREKEY_ID = "axolotl_cur_prekey_id";
+
+	private static final int NUM_TRUSTS_TO_CACHE = 100;
+
+	private final Account account;
+	private final XmppConnectionService mXmppConnectionService;
+
+	private IdentityKeyPair identityKeyPair;
+	private int localRegistrationId;
+	private int currentPreKeyId = 0;
+
+	private final LruCache<String, XmppAxolotlSession.Trust> trustCache =
+			new LruCache<String, XmppAxolotlSession.Trust>(NUM_TRUSTS_TO_CACHE) {
+				@Override
+				protected XmppAxolotlSession.Trust create(String fingerprint) {
+					return mXmppConnectionService.databaseBackend.isIdentityKeyTrusted(account, fingerprint);
+				}
+			};
+
+	private static IdentityKeyPair generateIdentityKeyPair() {
+		Log.i(Config.LOGTAG, AxolotlService.LOGPREFIX + " : " + "Generating axolotl IdentityKeyPair...");
+		ECKeyPair identityKeyPairKeys = Curve.generateKeyPair();
+		return new IdentityKeyPair(new IdentityKey(identityKeyPairKeys.getPublicKey()),
+				identityKeyPairKeys.getPrivateKey());
+	}
+
+	private static int generateRegistrationId() {
+		Log.i(Config.LOGTAG, AxolotlService.LOGPREFIX + " : " + "Generating axolotl registration ID...");
+		return KeyHelper.generateRegistrationId(true);
+	}
+
+	public SQLiteAxolotlStore(Account account, XmppConnectionService service) {
+		this.account = account;
+		this.mXmppConnectionService = service;
+		this.localRegistrationId = loadRegistrationId();
+		this.currentPreKeyId = loadCurrentPreKeyId();
+		for (SignedPreKeyRecord record : loadSignedPreKeys()) {
+			Log.d(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Got Axolotl signed prekey record:" + record.getId());
+		}
+	}
+
+	public int getCurrentPreKeyId() {
+		return currentPreKeyId;
+	}
+
+	// --------------------------------------
+	// IdentityKeyStore
+	// --------------------------------------
+
+	private IdentityKeyPair loadIdentityKeyPair() {
+		IdentityKeyPair ownKey = mXmppConnectionService.databaseBackend.loadOwnIdentityKeyPair(account);
+
+		if (ownKey != null) {
+			return ownKey;
+		} else {
+			Log.i(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Could not retrieve own IdentityKeyPair");
+			ownKey = generateIdentityKeyPair();
+			mXmppConnectionService.databaseBackend.storeOwnIdentityKeyPair(account, ownKey);
+		}
+		return ownKey;
+	}
+
+	private int loadRegistrationId() {
+		return loadRegistrationId(false);
+	}
+
+	private int loadRegistrationId(boolean regenerate) {
+		String regIdString = this.account.getKey(JSONKEY_REGISTRATION_ID);
+		int reg_id;
+		if (!regenerate && regIdString != null) {
+			reg_id = Integer.valueOf(regIdString);
+		} else {
+			Log.i(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Could not retrieve axolotl registration id for account " + account.getJid());
+			reg_id = generateRegistrationId();
+			boolean success = this.account.setKey(JSONKEY_REGISTRATION_ID, Integer.toString(reg_id));
+			if (success) {
+				mXmppConnectionService.databaseBackend.updateAccount(account);
+			} else {
+				Log.e(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Failed to write new key to the database!");
+			}
+		}
+		return reg_id;
+	}
+
+	private int loadCurrentPreKeyId() {
+		String regIdString = this.account.getKey(JSONKEY_CURRENT_PREKEY_ID);
+		int reg_id;
+		if (regIdString != null) {
+			reg_id = Integer.valueOf(regIdString);
+		} else {
+			Log.w(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Could not retrieve current prekey id for account " + account.getJid());
+			reg_id = 0;
+		}
+		return reg_id;
+	}
+
+	public void regenerate() {
+		mXmppConnectionService.databaseBackend.wipeAxolotlDb(account);
+		trustCache.evictAll();
+		account.setKey(JSONKEY_CURRENT_PREKEY_ID, Integer.toString(0));
+		identityKeyPair = loadIdentityKeyPair();
+		localRegistrationId = loadRegistrationId(true);
+		currentPreKeyId = 0;
+		mXmppConnectionService.updateAccountUi();
+	}
+
+	/**
+	 * Get the local client's identity key pair.
+	 *
+	 * @return The local client's persistent identity key pair.
+	 */
+	@Override
+	public IdentityKeyPair getIdentityKeyPair() {
+		if (identityKeyPair == null) {
+			identityKeyPair = loadIdentityKeyPair();
+		}
+		return identityKeyPair;
+	}
+
+	/**
+	 * Return the local client's registration ID.
+	 * <p/>
+	 * Clients should maintain a registration ID, a random number
+	 * between 1 and 16380 that's generated once at install time.
+	 *
+	 * @return the local client's registration ID.
+	 */
+	@Override
+	public int getLocalRegistrationId() {
+		return localRegistrationId;
+	}
+
+	/**
+	 * Save a remote client's identity key
+	 * <p/>
+	 * Store a remote client's identity key as trusted.
+	 *
+	 * @param name        The name of the remote client.
+	 * @param identityKey The remote client's identity key.
+	 */
+	@Override
+	public void saveIdentity(String name, IdentityKey identityKey) {
+		if (!mXmppConnectionService.databaseBackend.loadIdentityKeys(account, name).contains(identityKey)) {
+			mXmppConnectionService.databaseBackend.storeIdentityKey(account, name, identityKey);
+		}
+	}
+
+	/**
+	 * Verify a remote client's identity key.
+	 * <p/>
+	 * Determine whether a remote client's identity is trusted.  Convention is
+	 * that the TextSecure protocol is 'trust on first use.'  This means that
+	 * an identity key is considered 'trusted' if there is no entry for the recipient
+	 * in the local store, or if it matches the saved key for a recipient in the local
+	 * store.  Only if it mismatches an entry in the local store is it considered
+	 * 'untrusted.'
+	 *
+	 * @param name        The name of the remote client.
+	 * @param identityKey The identity key to verify.
+	 * @return true if trusted, false if untrusted.
+	 */
+	@Override
+	public boolean isTrustedIdentity(String name, IdentityKey identityKey) {
+		return true;
+	}
+
+	public XmppAxolotlSession.Trust getFingerprintTrust(String fingerprint) {
+		return (fingerprint == null)? null : trustCache.get(fingerprint);
+	}
+
+	public void setFingerprintTrust(String fingerprint, XmppAxolotlSession.Trust trust) {
+		mXmppConnectionService.databaseBackend.setIdentityKeyTrust(account, fingerprint, trust);
+		trustCache.remove(fingerprint);
+	}
+
+	public void setFingerprintCertificate(String fingerprint, X509Certificate x509Certificate) {
+		mXmppConnectionService.databaseBackend.setIdentityKeyCertificate(account, fingerprint, x509Certificate);
+	}
+
+	public X509Certificate getFingerprintCertificate(String fingerprint) {
+		return mXmppConnectionService.databaseBackend.getIdentityKeyCertifcate(account, fingerprint);
+	}
+
+	public Set<IdentityKey> getContactKeysWithTrust(String bareJid, XmppAxolotlSession.Trust trust) {
+		return mXmppConnectionService.databaseBackend.loadIdentityKeys(account, bareJid, trust);
+	}
+
+	public long getContactNumTrustedKeys(String bareJid) {
+		return mXmppConnectionService.databaseBackend.numTrustedKeys(account, bareJid);
+	}
+
+	// --------------------------------------
+	// SessionStore
+	// --------------------------------------
+
+	/**
+	 * Returns a copy of the {@link SessionRecord} corresponding to the recipientId + deviceId tuple,
+	 * or a new SessionRecord if one does not currently exist.
+	 * <p/>
+	 * It is important that implementations return a copy of the current durable information.  The
+	 * returned SessionRecord may be modified, but those changes should not have an effect on the
+	 * durable session state (what is returned by subsequent calls to this method) without the
+	 * store method being called here first.
+	 *
+	 * @param address The name and device ID of the remote client.
+	 * @return a copy of the SessionRecord corresponding to the recipientId + deviceId tuple, or
+	 * a new SessionRecord if one does not currently exist.
+	 */
+	@Override
+	public SessionRecord loadSession(AxolotlAddress address) {
+		SessionRecord session = mXmppConnectionService.databaseBackend.loadSession(this.account, address);
+		return (session != null) ? session : new SessionRecord();
+	}
+
+	/**
+	 * Returns all known devices with active sessions for a recipient
+	 *
+	 * @param name the name of the client.
+	 * @return all known sub-devices with active sessions.
+	 */
+	@Override
+	public List<Integer> getSubDeviceSessions(String name) {
+		return mXmppConnectionService.databaseBackend.getSubDeviceSessions(account,
+				new AxolotlAddress(name, 0));
+	}
+
+	/**
+	 * Commit to storage the {@link SessionRecord} for a given recipientId + deviceId tuple.
+	 *
+	 * @param address the address of the remote client.
+	 * @param record  the current SessionRecord for the remote client.
+	 */
+	@Override
+	public void storeSession(AxolotlAddress address, SessionRecord record) {
+		mXmppConnectionService.databaseBackend.storeSession(account, address, record);
+	}
+
+	/**
+	 * Determine whether there is a committed {@link SessionRecord} for a recipientId + deviceId tuple.
+	 *
+	 * @param address the address of the remote client.
+	 * @return true if a {@link SessionRecord} exists, false otherwise.
+	 */
+	@Override
+	public boolean containsSession(AxolotlAddress address) {
+		return mXmppConnectionService.databaseBackend.containsSession(account, address);
+	}
+
+	/**
+	 * Remove a {@link SessionRecord} for a recipientId + deviceId tuple.
+	 *
+	 * @param address the address of the remote client.
+	 */
+	@Override
+	public void deleteSession(AxolotlAddress address) {
+		mXmppConnectionService.databaseBackend.deleteSession(account, address);
+	}
+
+	/**
+	 * Remove the {@link SessionRecord}s corresponding to all devices of a recipientId.
+	 *
+	 * @param name the name of the remote client.
+	 */
+	@Override
+	public void deleteAllSessions(String name) {
+		AxolotlAddress address = new AxolotlAddress(name, 0);
+		mXmppConnectionService.databaseBackend.deleteAllSessions(account,
+				address);
+	}
+
+	// --------------------------------------
+	// PreKeyStore
+	// --------------------------------------
+
+	/**
+	 * Load a local PreKeyRecord.
+	 *
+	 * @param preKeyId the ID of the local PreKeyRecord.
+	 * @return the corresponding PreKeyRecord.
+	 * @throws InvalidKeyIdException when there is no corresponding PreKeyRecord.
+	 */
+	@Override
+	public PreKeyRecord loadPreKey(int preKeyId) throws InvalidKeyIdException {
+		PreKeyRecord record = mXmppConnectionService.databaseBackend.loadPreKey(account, preKeyId);
+		if (record == null) {
+			throw new InvalidKeyIdException("No such PreKeyRecord: " + preKeyId);
+		}
+		return record;
+	}
+
+	/**
+	 * Store a local PreKeyRecord.
+	 *
+	 * @param preKeyId the ID of the PreKeyRecord to store.
+	 * @param record   the PreKeyRecord.
+	 */
+	@Override
+	public void storePreKey(int preKeyId, PreKeyRecord record) {
+		mXmppConnectionService.databaseBackend.storePreKey(account, record);
+		currentPreKeyId = preKeyId;
+		boolean success = this.account.setKey(JSONKEY_CURRENT_PREKEY_ID, Integer.toString(preKeyId));
+		if (success) {
+			mXmppConnectionService.databaseBackend.updateAccount(account);
+		} else {
+			Log.e(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Failed to write new prekey id to the database!");
+		}
+	}
+
+	/**
+	 * @param preKeyId A PreKeyRecord ID.
+	 * @return true if the store has a record for the preKeyId, otherwise false.
+	 */
+	@Override
+	public boolean containsPreKey(int preKeyId) {
+		return mXmppConnectionService.databaseBackend.containsPreKey(account, preKeyId);
+	}
+
+	/**
+	 * Delete a PreKeyRecord from local storage.
+	 *
+	 * @param preKeyId The ID of the PreKeyRecord to remove.
+	 */
+	@Override
+	public void removePreKey(int preKeyId) {
+		mXmppConnectionService.databaseBackend.deletePreKey(account, preKeyId);
+	}
+
+	// --------------------------------------
+	// SignedPreKeyStore
+	// --------------------------------------
+
+	/**
+	 * Load a local SignedPreKeyRecord.
+	 *
+	 * @param signedPreKeyId the ID of the local SignedPreKeyRecord.
+	 * @return the corresponding SignedPreKeyRecord.
+	 * @throws InvalidKeyIdException when there is no corresponding SignedPreKeyRecord.
+	 */
+	@Override
+	public SignedPreKeyRecord loadSignedPreKey(int signedPreKeyId) throws InvalidKeyIdException {
+		SignedPreKeyRecord record = mXmppConnectionService.databaseBackend.loadSignedPreKey(account, signedPreKeyId);
+		if (record == null) {
+			throw new InvalidKeyIdException("No such SignedPreKeyRecord: " + signedPreKeyId);
+		}
+		return record;
+	}
+
+	/**
+	 * Load all local SignedPreKeyRecords.
+	 *
+	 * @return All stored SignedPreKeyRecords.
+	 */
+	@Override
+	public List<SignedPreKeyRecord> loadSignedPreKeys() {
+		return mXmppConnectionService.databaseBackend.loadSignedPreKeys(account);
+	}
+
+	/**
+	 * Store a local SignedPreKeyRecord.
+	 *
+	 * @param signedPreKeyId the ID of the SignedPreKeyRecord to store.
+	 * @param record         the SignedPreKeyRecord.
+	 */
+	@Override
+	public void storeSignedPreKey(int signedPreKeyId, SignedPreKeyRecord record) {
+		mXmppConnectionService.databaseBackend.storeSignedPreKey(account, record);
+	}
+
+	/**
+	 * @param signedPreKeyId A SignedPreKeyRecord ID.
+	 * @return true if the store has a record for the signedPreKeyId, otherwise false.
+	 */
+	@Override
+	public boolean containsSignedPreKey(int signedPreKeyId) {
+		return mXmppConnectionService.databaseBackend.containsSignedPreKey(account, signedPreKeyId);
+	}
+
+	/**
+	 * Delete a SignedPreKeyRecord from local storage.
+	 *
+	 * @param signedPreKeyId The ID of the SignedPreKeyRecord to remove.
+	 */
+	@Override
+	public void removeSignedPreKey(int signedPreKeyId) {
+		mXmppConnectionService.databaseBackend.deleteSignedPreKey(account, signedPreKeyId);
+	}
+}
diff --git a/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/XmppAxolotlMessage.java b/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/XmppAxolotlMessage.java
new file mode 100644
index 00000000..837b601c
--- /dev/null
+++ b/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/XmppAxolotlMessage.java
@@ -0,0 +1,249 @@
+package de.thedevstack.conversationsplus.crypto.axolotl;
+
+import android.util.Base64;
+import android.util.Log;
+
+import java.security.InvalidAlgorithmParameterException;
+import java.security.InvalidKeyException;
+import java.security.NoSuchAlgorithmException;
+import java.security.NoSuchProviderException;
+import java.security.SecureRandom;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import javax.crypto.BadPaddingException;
+import javax.crypto.Cipher;
+import javax.crypto.IllegalBlockSizeException;
+import javax.crypto.KeyGenerator;
+import javax.crypto.NoSuchPaddingException;
+import javax.crypto.SecretKey;
+import javax.crypto.spec.IvParameterSpec;
+import javax.crypto.spec.SecretKeySpec;
+
+import de.thedevstack.conversationsplus.Config;
+import de.thedevstack.conversationsplus.xml.Element;
+import de.thedevstack.conversationsplus.xmpp.jid.Jid;
+
+public class XmppAxolotlMessage {
+	public static final String CONTAINERTAG = "encrypted";
+	public static final String HEADER = "header";
+	public static final String SOURCEID = "sid";
+	public static final String KEYTAG = "key";
+	public static final String REMOTEID = "rid";
+	public static final String IVTAG = "iv";
+	public static final String PAYLOAD = "payload";
+
+	private static final String KEYTYPE = "AES";
+	private static final String CIPHERMODE = "AES/GCM/NoPadding";
+	private static final String PROVIDER = "BC";
+
+	private byte[] innerKey;
+	private byte[] ciphertext = null;
+	private byte[] iv = null;
+	private final Map<Integer, byte[]> keys;
+	private final Jid from;
+	private final int sourceDeviceId;
+
+	public static class XmppAxolotlPlaintextMessage {
+		private final String plaintext;
+		private final String fingerprint;
+
+		public XmppAxolotlPlaintextMessage(String plaintext, String fingerprint) {
+			this.plaintext = plaintext;
+			this.fingerprint = fingerprint;
+		}
+
+		public String getPlaintext() {
+			return plaintext;
+		}
+
+
+		public String getFingerprint() {
+			return fingerprint;
+		}
+	}
+
+	public static class XmppAxolotlKeyTransportMessage {
+		private final String fingerprint;
+		private final byte[] key;
+		private final byte[] iv;
+
+		public XmppAxolotlKeyTransportMessage(String fingerprint, byte[] key, byte[] iv) {
+			this.fingerprint = fingerprint;
+			this.key = key;
+			this.iv = iv;
+		}
+
+		public String getFingerprint() {
+			return fingerprint;
+		}
+
+		public byte[] getKey() {
+			return key;
+		}
+
+		public byte[] getIv() {
+			return iv;
+		}
+	}
+
+	private XmppAxolotlMessage(final Element axolotlMessage, final Jid from) throws IllegalArgumentException {
+		this.from = from;
+		Element header = axolotlMessage.findChild(HEADER);
+		this.sourceDeviceId = Integer.parseInt(header.getAttribute(SOURCEID));
+		List<Element> keyElements = header.getChildren();
+		this.keys = new HashMap<>(keyElements.size());
+		for (Element keyElement : keyElements) {
+			switch (keyElement.getName()) {
+				case KEYTAG:
+					try {
+						Integer recipientId = Integer.parseInt(keyElement.getAttribute(REMOTEID));
+						byte[] key = Base64.decode(keyElement.getContent(), Base64.DEFAULT);
+						this.keys.put(recipientId, key);
+					} catch (NumberFormatException e) {
+						throw new IllegalArgumentException(e);
+					}
+					break;
+				case IVTAG:
+					if (this.iv != null) {
+						throw new IllegalArgumentException("Duplicate iv entry");
+					}
+					iv = Base64.decode(keyElement.getContent(), Base64.DEFAULT);
+					break;
+				default:
+					Log.w(Config.LOGTAG, "Unexpected element in header: " + keyElement.toString());
+					break;
+			}
+		}
+		Element payloadElement = axolotlMessage.findChild(PAYLOAD);
+		if (payloadElement != null) {
+			ciphertext = Base64.decode(payloadElement.getContent(), Base64.DEFAULT);
+		}
+	}
+
+	public XmppAxolotlMessage(Jid from, int sourceDeviceId) {
+		this.from = from;
+		this.sourceDeviceId = sourceDeviceId;
+		this.keys = new HashMap<>();
+		this.iv = generateIv();
+		this.innerKey = generateKey();
+	}
+
+	public static XmppAxolotlMessage fromElement(Element element, Jid from) {
+		return new XmppAxolotlMessage(element, from);
+	}
+
+	private static byte[] generateKey() {
+		try {
+			KeyGenerator generator = KeyGenerator.getInstance(KEYTYPE);
+			generator.init(128);
+			return generator.generateKey().getEncoded();
+		} catch (NoSuchAlgorithmException e) {
+			Log.e(Config.LOGTAG, e.getMessage());
+			return null;
+		}
+	}
+
+	private static byte[] generateIv() {
+		SecureRandom random = new SecureRandom();
+		byte[] iv = new byte[16];
+		random.nextBytes(iv);
+		return iv;
+	}
+
+	public void encrypt(String plaintext) throws CryptoFailedException {
+		try {
+			SecretKey secretKey = new SecretKeySpec(innerKey, KEYTYPE);
+			IvParameterSpec ivSpec = new IvParameterSpec(iv);
+			Cipher cipher = Cipher.getInstance(CIPHERMODE, PROVIDER);
+			cipher.init(Cipher.ENCRYPT_MODE, secretKey, ivSpec);
+			this.innerKey = secretKey.getEncoded();
+			this.ciphertext = cipher.doFinal(plaintext.getBytes());
+		} catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException
+				| IllegalBlockSizeException | BadPaddingException | NoSuchProviderException
+				| InvalidAlgorithmParameterException e) {
+			throw new CryptoFailedException(e);
+		}
+	}
+
+	public Jid getFrom() {
+		return this.from;
+	}
+
+	public int getSenderDeviceId() {
+		return sourceDeviceId;
+	}
+
+	public byte[] getCiphertext() {
+		return ciphertext;
+	}
+
+	public void addDevice(XmppAxolotlSession session) {
+		byte[] key = session.processSending(innerKey);
+		if (key != null) {
+			keys.put(session.getRemoteAddress().getDeviceId(), key);
+		}
+	}
+
+	public byte[] getInnerKey() {
+		return innerKey;
+	}
+
+	public byte[] getIV() {
+		return this.iv;
+	}
+
+	public Element toElement() {
+		Element encryptionElement = new Element(CONTAINERTAG, AxolotlService.PEP_PREFIX);
+		Element headerElement = encryptionElement.addChild(HEADER);
+		headerElement.setAttribute(SOURCEID, sourceDeviceId);
+		for (Map.Entry<Integer, byte[]> keyEntry : keys.entrySet()) {
+			Element keyElement = new Element(KEYTAG);
+			keyElement.setAttribute(REMOTEID, keyEntry.getKey());
+			keyElement.setContent(Base64.encodeToString(keyEntry.getValue(), Base64.DEFAULT));
+			headerElement.addChild(keyElement);
+		}
+		headerElement.addChild(IVTAG).setContent(Base64.encodeToString(iv, Base64.DEFAULT));
+		if (ciphertext != null) {
+			Element payload = encryptionElement.addChild(PAYLOAD);
+			payload.setContent(Base64.encodeToString(ciphertext, Base64.DEFAULT));
+		}
+		return encryptionElement;
+	}
+
+	private byte[] unpackKey(XmppAxolotlSession session, Integer sourceDeviceId) {
+		byte[] encryptedKey = keys.get(sourceDeviceId);
+		return (encryptedKey != null) ? session.processReceiving(encryptedKey) : null;
+	}
+
+	public XmppAxolotlKeyTransportMessage getParameters(XmppAxolotlSession session, Integer sourceDeviceId) {
+		byte[] key = unpackKey(session, sourceDeviceId);
+		return (key != null)
+				? new XmppAxolotlKeyTransportMessage(session.getFingerprint(), key, getIV())
+				: null;
+	}
+
+	public XmppAxolotlPlaintextMessage decrypt(XmppAxolotlSession session, Integer sourceDeviceId) throws CryptoFailedException {
+		XmppAxolotlPlaintextMessage plaintextMessage = null;
+		byte[] key = unpackKey(session, sourceDeviceId);
+		if (key != null) {
+			try {
+				Cipher cipher = Cipher.getInstance(CIPHERMODE, PROVIDER);
+				SecretKeySpec keySpec = new SecretKeySpec(key, KEYTYPE);
+				IvParameterSpec ivSpec = new IvParameterSpec(iv);
+
+				cipher.init(Cipher.DECRYPT_MODE, keySpec, ivSpec);
+
+				String plaintext = new String(cipher.doFinal(ciphertext));
+				plaintextMessage = new XmppAxolotlPlaintextMessage(plaintext, session.getFingerprint());
+
+			} catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException
+					| InvalidAlgorithmParameterException | IllegalBlockSizeException
+					| BadPaddingException | NoSuchProviderException e) {
+				throw new CryptoFailedException(e);
+			}
+		}
+		return plaintextMessage;
+	}
+}
diff --git a/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/XmppAxolotlSession.java b/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/XmppAxolotlSession.java
new file mode 100644
index 00000000..47b2133a
--- /dev/null
+++ b/src/main/java/de/thedevstack/conversationsplus/crypto/axolotl/XmppAxolotlSession.java
@@ -0,0 +1,221 @@
+package de.thedevstack.conversationsplus.crypto.axolotl;
+
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.util.Log;
+
+import org.whispersystems.libaxolotl.AxolotlAddress;
+import org.whispersystems.libaxolotl.DuplicateMessageException;
+import org.whispersystems.libaxolotl.IdentityKey;
+import org.whispersystems.libaxolotl.InvalidKeyException;
+import org.whispersystems.libaxolotl.InvalidKeyIdException;
+import org.whispersystems.libaxolotl.InvalidMessageException;
+import org.whispersystems.libaxolotl.InvalidVersionException;
+import org.whispersystems.libaxolotl.LegacyMessageException;
+import org.whispersystems.libaxolotl.NoSessionException;
+import org.whispersystems.libaxolotl.SessionCipher;
+import org.whispersystems.libaxolotl.UntrustedIdentityException;
+import org.whispersystems.libaxolotl.protocol.CiphertextMessage;
+import org.whispersystems.libaxolotl.protocol.PreKeyWhisperMessage;
+import org.whispersystems.libaxolotl.protocol.WhisperMessage;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import de.thedevstack.conversationsplus.Config;
+import de.thedevstack.conversationsplus.entities.Account;
+
+public class XmppAxolotlSession {
+	private final SessionCipher cipher;
+	private final SQLiteAxolotlStore sqLiteAxolotlStore;
+	private final AxolotlAddress remoteAddress;
+	private final Account account;
+	private IdentityKey identityKey;
+	private Integer preKeyId = null;
+	private boolean fresh = true;
+
+	public enum Trust {
+		UNDECIDED(0),
+		TRUSTED(1),
+		UNTRUSTED(2),
+		COMPROMISED(3),
+		INACTIVE_TRUSTED(4),
+		INACTIVE_UNDECIDED(5),
+		INACTIVE_UNTRUSTED(6),
+		TRUSTED_X509(7),
+		INACTIVE_TRUSTED_X509(8);
+
+		private static final Map<Integer, Trust> trustsByValue = new HashMap<>();
+
+		static {
+			for (Trust trust : Trust.values()) {
+				trustsByValue.put(trust.getCode(), trust);
+			}
+		}
+
+		private final int code;
+
+		Trust(int code) {
+			this.code = code;
+		}
+
+		public int getCode() {
+			return this.code;
+		}
+
+		public String toString() {
+			switch (this) {
+				case UNDECIDED:
+					return "Trust undecided " + getCode();
+				case TRUSTED:
+					return "Trusted " + getCode();
+				case COMPROMISED:
+					return "Compromised " + getCode();
+				case INACTIVE_TRUSTED:
+					return "Inactive (Trusted)" + getCode();
+				case INACTIVE_UNDECIDED:
+					return "Inactive (Undecided)" + getCode();
+				case INACTIVE_UNTRUSTED:
+					return "Inactive (Untrusted)" + getCode();
+				case TRUSTED_X509:
+					return "Trusted (X509) " + getCode();
+				case INACTIVE_TRUSTED_X509:
+					return "Inactive (Trusted (X509)) " + getCode();
+				case UNTRUSTED:
+				default:
+					return "Untrusted " + getCode();
+			}
+		}
+
+		public static Trust fromBoolean(Boolean trusted) {
+			return trusted ? TRUSTED : UNTRUSTED;
+		}
+
+		public static Trust fromCode(int code) {
+			return trustsByValue.get(code);
+		}
+
+		public boolean trusted() {
+			return this == TRUSTED_X509 || this == TRUSTED;
+		}
+
+		public boolean trustedInactive() {
+			return this == INACTIVE_TRUSTED_X509 || this == INACTIVE_TRUSTED;
+		}
+	}
+
+	public XmppAxolotlSession(Account account, SQLiteAxolotlStore store, AxolotlAddress remoteAddress, IdentityKey identityKey) {
+		this(account, store, remoteAddress);
+		this.identityKey = identityKey;
+	}
+
+	public XmppAxolotlSession(Account account, SQLiteAxolotlStore store, AxolotlAddress remoteAddress) {
+		this.cipher = new SessionCipher(store, remoteAddress);
+		this.remoteAddress = remoteAddress;
+		this.sqLiteAxolotlStore = store;
+		this.account = account;
+	}
+
+	public Integer getPreKeyId() {
+		return preKeyId;
+	}
+
+	public void resetPreKeyId() {
+
+		preKeyId = null;
+	}
+
+	public String getFingerprint() {
+		return identityKey == null ? null : identityKey.getFingerprint().replaceAll("\\s", "");
+	}
+
+	public IdentityKey getIdentityKey() {
+		return identityKey;
+	}
+
+	public AxolotlAddress getRemoteAddress() {
+		return remoteAddress;
+	}
+
+	public boolean isFresh() {
+		return fresh;
+	}
+
+	public void setNotFresh() {
+		this.fresh = false;
+	}
+
+	protected void setTrust(Trust trust) {
+		sqLiteAxolotlStore.setFingerprintTrust(getFingerprint(), trust);
+	}
+
+	protected Trust getTrust() {
+		Trust trust = sqLiteAxolotlStore.getFingerprintTrust(getFingerprint());
+		return (trust == null) ? Trust.UNDECIDED : trust;
+	}
+
+	@Nullable
+	public byte[] processReceiving(byte[] encryptedKey) {
+		byte[] plaintext = null;
+		Trust trust = getTrust();
+		switch (trust) {
+			case INACTIVE_TRUSTED:
+			case UNDECIDED:
+			case UNTRUSTED:
+			case TRUSTED:
+			case INACTIVE_TRUSTED_X509:
+			case TRUSTED_X509:
+				try {
+					try {
+						PreKeyWhisperMessage message = new PreKeyWhisperMessage(encryptedKey);
+						Log.i(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "PreKeyWhisperMessage received, new session ID:" + message.getSignedPreKeyId() + "/" + message.getPreKeyId());
+						IdentityKey msgIdentityKey = message.getIdentityKey();
+						if (this.identityKey != null && !this.identityKey.equals(msgIdentityKey)) {
+							Log.e(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Had session with fingerprint " + this.getFingerprint() + ", received message with fingerprint " + msgIdentityKey.getFingerprint());
+						} else {
+							this.identityKey = msgIdentityKey;
+							plaintext = cipher.decrypt(message);
+							if (message.getPreKeyId().isPresent()) {
+								preKeyId = message.getPreKeyId().get();
+							}
+						}
+					} catch (InvalidMessageException | InvalidVersionException e) {
+						Log.i(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "WhisperMessage received");
+						WhisperMessage message = new WhisperMessage(encryptedKey);
+						plaintext = cipher.decrypt(message);
+					} catch (InvalidKeyException | InvalidKeyIdException | UntrustedIdentityException e) {
+						Log.w(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Error decrypting axolotl header, " + e.getClass().getName() + ": " + e.getMessage());
+					}
+				} catch (LegacyMessageException | InvalidMessageException | DuplicateMessageException | NoSessionException e) {
+					Log.w(Config.LOGTAG, AxolotlServiceImpl.getLogprefix(account) + "Error decrypting axolotl header, " + e.getClass().getName() + ": " + e.getMessage());
+				}
+
+				if (plaintext != null) {
+					if (trust == Trust.INACTIVE_TRUSTED) {
+						setTrust(Trust.TRUSTED);
+					} else if (trust == Trust.INACTIVE_TRUSTED_X509) {
+						setTrust(Trust.TRUSTED_X509);
+					}
+				}
+
+				break;
+
+			case COMPROMISED:
+			default:
+				// ignore
+				break;
+		}
+		return plaintext;
+	}
+
+	@Nullable
+	public byte[] processSending(@NonNull byte[] outgoingMessage) {
+		Trust trust = getTrust();
+		if (trust.trusted()) {
+			CiphertextMessage ciphertextMessage = cipher.encrypt(outgoingMessage);
+			return ciphertextMessage.serialize();
+		} else {
+			return null;
+		}
+	}
+}