Reworked axolotl protocol layer

Numerous fixes

src/main/java/eu/siacs/conversations/crypto/axolotl/AxolotlService.java

@@ -1,15 +1,29 @@
 package eu.siacs.conversations.crypto.axolotl;
 
+import android.util.Base64;
 import android.util.Log;
 
 import org.whispersystems.libaxolotl.AxolotlAddress;
+import org.whispersystems.libaxolotl.DuplicateMessageException;
 import org.whispersystems.libaxolotl.IdentityKey;
 import org.whispersystems.libaxolotl.IdentityKeyPair;
 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.SessionBuilder;
+import org.whispersystems.libaxolotl.SessionCipher;
+import org.whispersystems.libaxolotl.UntrustedIdentityException;
 import org.whispersystems.libaxolotl.ecc.Curve;
 import org.whispersystems.libaxolotl.ecc.ECKeyPair;
+import org.whispersystems.libaxolotl.ecc.ECPublicKey;
+import org.whispersystems.libaxolotl.protocol.CiphertextMessage;
+import org.whispersystems.libaxolotl.protocol.PreKeyWhisperMessage;
+import org.whispersystems.libaxolotl.protocol.WhisperMessage;
 import org.whispersystems.libaxolotl.state.AxolotlStore;
+import org.whispersystems.libaxolotl.state.PreKeyBundle;
 import org.whispersystems.libaxolotl.state.PreKeyRecord;
 import org.whispersystems.libaxolotl.state.SessionRecord;
 import org.whispersystems.libaxolotl.state.SignedPreKeyRecord;
@@ -17,43 +31,50 @@ import org.whispersystems.libaxolotl.util.KeyHelper;
 
 import java.util.ArrayList;
 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 eu.siacs.conversations.Config;
 import eu.siacs.conversations.entities.Account;
+import eu.siacs.conversations.entities.Contact;
 import eu.siacs.conversations.entities.Conversation;
-import eu.siacs.conversations.entities.Message;
 import eu.siacs.conversations.services.XmppConnectionService;
 import eu.siacs.conversations.xmpp.jid.InvalidJidException;
 import eu.siacs.conversations.xmpp.jid.Jid;
 
 public class AxolotlService {
 
-    private Account account;
+    private final Account account;
-    private XmppConnectionService mXmppConnectionService;
+    private final XmppConnectionService mXmppConnectionService;
-    private SQLiteAxolotlStore axolotlStore;
+    private final SQLiteAxolotlStore axolotlStore;
-    private Map<Jid,XmppAxolotlSession> sessions;
+    private final SessionMap sessions;
+    private int ownDeviceId;
 
     public static 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 = "signed_prekeys";
+        public static final String SESSION_TABLENAME = "sessions";
-        public static final String NAME = "name";
+        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 ACCOUNT = "account";
+        public static final String NAME = "name";
+        public static final String TRUSTED = "trusted";
 
         public static final String JSONKEY_IDENTITY_KEY_PAIR = "axolotl_key";
         public static final String JSONKEY_REGISTRATION_ID = "axolotl_reg_id";
+        public static final String JSONKEY_CURRENT_PREKEY_ID = "axolotl_cur_prekey_id";
 
         private final Account account;
         private final XmppConnectionService mXmppConnectionService;
 
         private final IdentityKeyPair identityKeyPair;
         private final int localRegistrationId;
+        private int currentPreKeyId = 0;
 
 
         private static IdentityKeyPair generateIdentityKeyPair() {
@@ -75,6 +96,14 @@ public class AxolotlService {
             this.mXmppConnectionService = service;
             this.identityKeyPair = loadIdentityKeyPair();
             this.localRegistrationId = loadRegistrationId();
+            this.currentPreKeyId = loadCurrentPreKeyId();
+            for( SignedPreKeyRecord record:loadSignedPreKeys()) {
+                Log.d(Config.LOGTAG, "Got Axolotl signed prekey record:" + record.getId());
+            }
+        }
+
+        public int getCurrentPreKeyId() {
+            return currentPreKeyId;
         }
 
         // --------------------------------------
@@ -86,21 +115,22 @@ public class AxolotlService {
             IdentityKeyPair ownKey;
             if( serializedKey != null ) {
                 try {
-                    ownKey = new IdentityKeyPair(serializedKey.getBytes());
+                    ownKey = new IdentityKeyPair(Base64.decode(serializedKey,Base64.DEFAULT));
+                    return ownKey;
                 } catch (InvalidKeyException e) {
                     Log.d(Config.LOGTAG, "Invalid key stored for account " + account.getJid() + ": " + e.getMessage());
-                    return null;
+//                    return null;
                 }
-            } else {
+            } //else {
                 Log.d(Config.LOGTAG, "Could not retrieve axolotl key for account " + account.getJid());
                 ownKey = generateIdentityKeyPair();
-                boolean success = this.account.setKey(JSONKEY_IDENTITY_KEY_PAIR, new String(ownKey.serialize()));
+                boolean success = this.account.setKey(JSONKEY_IDENTITY_KEY_PAIR, Base64.encodeToString(ownKey.serialize(), Base64.DEFAULT));
                 if(success) {
                     mXmppConnectionService.databaseBackend.updateAccount(account);
                 } else {
                     Log.e(Config.LOGTAG, "Failed to write new key to the database!");
                 }
-            }
+            //}
             return ownKey;
         }
 
@@ -122,6 +152,19 @@ public class AxolotlService {
             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.d(Config.LOGTAG, "Could not retrieve current prekey id for account " + account.getJid());
+                reg_id = 0;
+            }
+            return reg_id;
+        }
+
+
         /**
          * Get the local client's identity key pair.
          *
@@ -159,7 +202,7 @@ public class AxolotlService {
                 Jid contactJid = Jid.fromString(name);
                 Conversation conversation = this.mXmppConnectionService.find(this.account, contactJid);
                 if (conversation != null) {
-                    conversation.getContact().addAxolotlIdentityKey(identityKey, false);
+                    conversation.getContact().addAxolotlIdentityKey(identityKey);
                     mXmppConnectionService.updateConversationUi();
                     mXmppConnectionService.syncRosterToDisk(conversation.getAccount());
                 }
@@ -188,8 +231,8 @@ public class AxolotlService {
                 Jid contactJid = Jid.fromString(name);
                 Conversation conversation = this.mXmppConnectionService.find(this.account, contactJid);
                 if (conversation != null) {
-                    List<IdentityKey> trustedKeys = conversation.getContact().getTrustedAxolotlIdentityKeys();
+                    List<IdentityKey> trustedKeys = conversation.getContact().getAxolotlIdentityKeys();
-                    return trustedKeys.contains(identityKey);
+                    return trustedKeys.isEmpty() || trustedKeys.contains(identityKey);
                 } else {
                     return false;
                 }
@@ -274,7 +317,15 @@ public class AxolotlService {
         @Override
         public void deleteAllSessions(String name) {
             mXmppConnectionService.databaseBackend.deleteAllSessions(account,
-                    new AxolotlAddress(name,0));
+                    new AxolotlAddress(name, 0));
+        }
+
+        public boolean isTrustedSession(AxolotlAddress address) {
+            return mXmppConnectionService.databaseBackend.isTrustedSession(this.account, address);
+        }
+
+        public void setTrustedSession(AxolotlAddress address, boolean trusted) {
+            mXmppConnectionService.databaseBackend.setTrustedSession(this.account, address,trusted);
         }
 
         // --------------------------------------
@@ -292,7 +343,7 @@ public class AxolotlService {
         public PreKeyRecord loadPreKey(int preKeyId) throws InvalidKeyIdException {
             PreKeyRecord record = mXmppConnectionService.databaseBackend.loadPreKey(account, preKeyId);
             if(record == null) {
-                throw new InvalidKeyIdException("No such PreKeyRecord!");
+                throw new InvalidKeyIdException("No such PreKeyRecord: " + preKeyId);
             }
             return record;
         }
@@ -306,6 +357,13 @@ public class AxolotlService {
         @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, "Failed to write new prekey id to the database!");
+            }
         }
 
         /**
@@ -342,7 +400,7 @@ public class AxolotlService {
         public SignedPreKeyRecord loadSignedPreKey(int signedPreKeyId) throws InvalidKeyIdException {
             SignedPreKeyRecord record = mXmppConnectionService.databaseBackend.loadSignedPreKey(account, signedPreKeyId);
             if(record == null) {
-                throw new InvalidKeyIdException("No such PreKeyRecord!");
+                throw new InvalidKeyIdException("No such SignedPreKeyRecord: " + signedPreKeyId);
             }
             return record;
         }
@@ -388,53 +446,229 @@ public class AxolotlService {
         }
     }
 
-    private static class XmppAxolotlSession {
+    public static class XmppAxolotlSession {
-        private List<Message> untrustedMessages;
+        private SessionCipher cipher;
-        private AxolotlStore axolotlStore;
+        private boolean isTrusted = false;
+        private SQLiteAxolotlStore sqLiteAxolotlStore;
+        private AxolotlAddress remoteAddress;
 
-        public XmppAxolotlSession(SQLiteAxolotlStore axolotlStore) {
+        public XmppAxolotlSession(SQLiteAxolotlStore store, AxolotlAddress remoteAddress) {
-            this.untrustedMessages = new ArrayList<>();
+            this.cipher = new SessionCipher(store, remoteAddress);
-            this.axolotlStore = axolotlStore;
+            this.remoteAddress = remoteAddress;
+            this.sqLiteAxolotlStore = store;
+            this.isTrusted = sqLiteAxolotlStore.isTrustedSession(remoteAddress);
         }
 
         public void trust() {
-            for (Message message : this.untrustedMessages) {
+            sqLiteAxolotlStore.setTrustedSession(remoteAddress, true);
-                message.trust();
+            this.isTrusted = true;
-            }
-            this.untrustedMessages = null;
         }
 
         public boolean isTrusted() {
-            return (this.untrustedMessages == null);
+            return this.isTrusted;
         }
 
-        public String processReceiving(XmppAxolotlMessage incomingMessage) {
+        public byte[] processReceiving(XmppAxolotlMessage.XmppAxolotlMessageHeader incomingHeader) {
-            return null;
+            byte[] plaintext = null;
+            try {
+                try {
+                    PreKeyWhisperMessage message = new PreKeyWhisperMessage(incomingHeader.getContents());
+                    Log.d(Config.LOGTAG,"PreKeyWhisperMessage ID:" + message.getSignedPreKeyId() + "/" + message.getPreKeyId());
+                    plaintext = cipher.decrypt(message);
+                } catch (InvalidMessageException|InvalidVersionException e) {
+                    WhisperMessage message = new WhisperMessage(incomingHeader.getContents());
+                    plaintext = cipher.decrypt(message);
+                } catch (InvalidKeyException|InvalidKeyIdException| UntrustedIdentityException e) {
+                    Log.d(Config.LOGTAG, "Error decrypting axolotl header: " + e.getMessage());
+                }
+            } catch (LegacyMessageException|InvalidMessageException e) {
+                Log.d(Config.LOGTAG, "Error decrypting axolotl header: " + e.getMessage());
+            } catch (DuplicateMessageException|NoSessionException e) {
+                Log.d(Config.LOGTAG, "Error decrypting axolotl header: " + e.getMessage());
+            }
+            return plaintext;
         }
 
-        public XmppAxolotlMessage processSending(String outgoingMessage) {
+        public XmppAxolotlMessage.XmppAxolotlMessageHeader processSending(byte[] outgoingMessage) {
+            CiphertextMessage ciphertextMessage = cipher.encrypt(outgoingMessage);
+            XmppAxolotlMessage.XmppAxolotlMessageHeader header =
+                    new XmppAxolotlMessage.XmppAxolotlMessageHeader(remoteAddress.getDeviceId(),
+                            ciphertextMessage.serialize());
+            return header;
+        }
+    }
+
+    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();
+            }
+        }
+
+
+    }
+
+    private static class SessionMap extends AxolotlAddressMap<XmppAxolotlSession> {
+
+        public SessionMap(SQLiteAxolotlStore store, Account account) {
+            super();
+            this.fillMap(store, account);
+        }
+
+        private void fillMap(SQLiteAxolotlStore store, Account account) {
+            for(Contact contact:account.getRoster().getContacts()){
+                Jid bareJid = contact.getJid().toBareJid();
+                if(bareJid == null) {
+                    continue; // FIXME: handle this?
+                }
+                String address = bareJid.toString();
+                List<Integer> deviceIDs = store.getSubDeviceSessions(address);
+                for(Integer deviceId:deviceIDs) {
+                    AxolotlAddress axolotlAddress = new AxolotlAddress(address, deviceId);
+                    this.put(axolotlAddress, new XmppAxolotlSession(store, axolotlAddress));
+                }
+            }
+        }
+
+    }
+
     }
 
     public AxolotlService(Account account, XmppConnectionService connectionService) {
         this.mXmppConnectionService = connectionService;
         this.account = account;
         this.axolotlStore = new SQLiteAxolotlStore(this.account, this.mXmppConnectionService);
-        this.sessions = new HashMap<>();
+        this.sessions = new SessionMap(axolotlStore, account);
+        this.ownDeviceId = axolotlStore.getLocalRegistrationId();
     }
 
-    public void trustSession(Jid counterpart) {
+    public void trustSession(AxolotlAddress counterpart) {
         XmppAxolotlSession session = sessions.get(counterpart);
         if(session != null) {
             session.trust();
         }
     }
 
-    public boolean isTrustedSession(Jid counterpart) {
+    public boolean isTrustedSession(AxolotlAddress counterpart) {
         XmppAxolotlSession session = sessions.get(counterpart);
         return session != null && session.isTrusted();
     }
 
+    private AxolotlAddress getAddressForJid(Jid jid) {
+        return new AxolotlAddress(jid.toString(), 0);
+    }
 
+    private Set<XmppAxolotlSession> findOwnSessions() {
+        AxolotlAddress ownAddress = getAddressForJid(account.getJid());
+        Set<XmppAxolotlSession> ownDeviceSessions = new HashSet<>(this.sessions.getAll(ownAddress).values());
+        return ownDeviceSessions;
+    }
+
+    private Set<XmppAxolotlSession> findSessionsforContact(Contact contact) {
+        AxolotlAddress contactAddress = getAddressForJid(contact.getJid());
+        Set<XmppAxolotlSession> sessions = new HashSet<>(this.sessions.getAll(contactAddress).values());
+        return sessions;
+    }
+
+    private boolean hasAny(Contact contact) {
+        AxolotlAddress contactAddress = getAddressForJid(contact.getJid());
+        return sessions.hasAny(contactAddress);
+    }
+
+    public int getOwnDeviceId() {
+        return ownDeviceId;
+    }
+
+    private void createSessionsIfNeeded(Contact contact) throws NoSessionsCreatedException {
+    }
+
+    public XmppAxolotlMessage processSending(Contact contact, String outgoingMessage) throws NoSessionsCreatedException {
+        XmppAxolotlMessage message = new XmppAxolotlMessage(contact, ownDeviceId, outgoingMessage);
+        createSessionsIfNeeded(contact);
+        Log.d(Config.LOGTAG, "Building axolotl foreign headers...");
+
+        for(XmppAxolotlSession session : findSessionsforContact(contact)) {
+//            if(!session.isTrusted()) {
+                // TODO: handle this properly
+  //              continue;
+    //        }
+            message.addHeader(session.processSending(message.getInnerKey()));
+        }
+        Log.d(Config.LOGTAG, "Building axolotl own headers...");
+        for(XmppAxolotlSession session : findOwnSessions()) {
+    //        if(!session.isTrusted()) {
+                // TODO: handle this properly
+      //          continue;
+        //    }
+            message.addHeader(session.processSending(message.getInnerKey()));
+        }
+
+        return message;
+    }
+
+    public XmppAxolotlMessage.XmppAxolotlPlaintextMessage processReceiving(XmppAxolotlMessage message) {
+        XmppAxolotlMessage.XmppAxolotlPlaintextMessage plaintextMessage = null;
+        AxolotlAddress senderAddress = new AxolotlAddress(message.getContact().getJid().toBareJid().toString(),
+                message.getSenderDeviceId());
+
+        XmppAxolotlSession session = sessions.get(senderAddress);
+        if (session == null) {
+            Log.d(Config.LOGTAG, "No axolotl session found while parsing received message " + message);
+            // TODO: handle this properly
+            session = new XmppAxolotlSession(axolotlStore, senderAddress);
+
+        }
+
+        for(XmppAxolotlMessage.XmppAxolotlMessageHeader header : message.getHeaders()) {
+            if (header.getRecipientDeviceId() == ownDeviceId) {
+                Log.d(Config.LOGTAG, "Found axolotl header matching own device ID, processing...");
+                byte[] payloadKey = session.processReceiving(header);
+                if (payloadKey != null) {
+                    Log.d(Config.LOGTAG, "Got payload key from axolotl header. Decrypting message...");
+                    plaintextMessage = message.decrypt(session, payloadKey);
+                }
+            }
+        }
+
+        return plaintextMessage;
+    }
 }

src/main/java/eu/siacs/conversations/crypto/axolotl/NoSessionsCreatedException.java

@@ -0,0 +1,4 @@
+package eu.siacs.conversations.crypto.axolotl;
+
+public class NoSessionsCreatedException extends Throwable{
+}

src/main/java/eu/siacs/conversations/crypto/axolotl/XmppAxolotlMessage.java

@@ -1,4 +1,184 @@
 package eu.siacs.conversations.crypto.axolotl;
 
+import android.util.Base64;
+
+import java.security.InvalidAlgorithmParameterException;
+import java.security.NoSuchAlgorithmException;
+import java.security.InvalidKeyException;
+import java.util.HashSet;
+import java.util.Set;
+
+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 eu.siacs.conversations.entities.Contact;
+import eu.siacs.conversations.xml.Element;
+
 public class XmppAxolotlMessage {
+    private byte[] innerKey;
+    private byte[] ciphertext;
+    private byte[] iv;
+    private final Set<XmppAxolotlMessageHeader> headers;
+    private final Contact contact;
+    private final int sourceDeviceId;
+
+    public static class XmppAxolotlMessageHeader {
+        private final int recipientDeviceId;
+        private final byte[] content;
+
+        public XmppAxolotlMessageHeader(int deviceId, byte[] content) {
+            this.recipientDeviceId = deviceId;
+            this.content = content;
+        }
+
+        public XmppAxolotlMessageHeader(Element header) {
+            if("header".equals(header.getName())) {
+                this.recipientDeviceId = Integer.parseInt(header.getAttribute("rid"));
+                this.content = Base64.decode(header.getContent(),Base64.DEFAULT);
+            } else {
+                throw new IllegalArgumentException("Argument not a <header> Element!");
+            }
+        }
+        
+        public int getRecipientDeviceId() {
+            return recipientDeviceId;
+        }
+
+        public byte[] getContents() {
+            return content;
+        }
+
+        public Element toXml() {
+            Element headerElement = new Element("header");
+            // TODO: generate XML
+            headerElement.setAttribute("rid", getRecipientDeviceId());
+            headerElement.setContent(Base64.encodeToString(getContents(), Base64.DEFAULT));
+            return headerElement;
+        }
+    }
+
+    public static class XmppAxolotlPlaintextMessage {
+        private final AxolotlService.XmppAxolotlSession session;
+        private final String plaintext;
+
+        public XmppAxolotlPlaintextMessage(AxolotlService.XmppAxolotlSession session, String plaintext) {
+            this.session = session;
+            this.plaintext = plaintext;
+        }
+
+        public String getPlaintext() {
+            return plaintext;
+        }
+    }
+
+    public XmppAxolotlMessage(Contact contact, Element axolotlMessage) {
+        this.contact = contact;
+        this.sourceDeviceId = Integer.parseInt(axolotlMessage.getAttribute("id"));
+        this.headers = new HashSet<>();
+        for(Element child:axolotlMessage.getChildren()) {
+            switch(child.getName()) {
+                case "header":
+                    headers.add(new XmppAxolotlMessageHeader(child));
+                    break;
+                case "message":
+                    iv = Base64.decode(child.getAttribute("iv"),Base64.DEFAULT);
+                    ciphertext = Base64.decode(child.getContent(),Base64.DEFAULT);
+                    break;
+                default:
+                    break;
+            }
+        }
+    }
+
+    public XmppAxolotlMessage(Contact contact, int sourceDeviceId, String plaintext) {
+        this.contact = contact;
+        this.sourceDeviceId = sourceDeviceId;
+        this.headers = new HashSet<>();
+        this.encrypt(plaintext);
+    }
+
+    private void encrypt(String plaintext) {
+        try {
+            KeyGenerator generator = KeyGenerator.getInstance("AES");
+            generator.init(128);
+            SecretKey secretKey = generator.generateKey();
+            Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding");
+            cipher.init(Cipher.ENCRYPT_MODE, secretKey);
+            this.innerKey = secretKey.getEncoded();
+            this.iv = cipher.getIV();
+            this.ciphertext = cipher.doFinal(plaintext.getBytes());
+        } catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException
+                | IllegalBlockSizeException | BadPaddingException e) {
+
+        }
+    }
+
+    public Contact getContact() {
+        return this.contact;
+    }
+
+    public int getSenderDeviceId() {
+        return sourceDeviceId;
+    }
+    
+    public byte[] getCiphertext() {
+        return ciphertext;
+    }
+
+    public Set<XmppAxolotlMessageHeader> getHeaders() {
+        return headers;
+    }
+
+    public void addHeader(XmppAxolotlMessageHeader header) {
+        headers.add(header);
+    }
+
+    public byte[] getInnerKey(){
+        return innerKey;
+    }
+
+    public byte[] getIV() {
+        return this.iv;
+    }
+
+    public Element toXml() {
+        // TODO: generate outer XML, add in header XML
+        Element message= new Element("axolotl_message", AxolotlService.PEP_PREFIX);
+        message.setAttribute("id", sourceDeviceId);
+        for(XmppAxolotlMessageHeader header: headers) {
+            message.addChild(header.toXml());
+        }
+        Element payload = message.addChild("message");
+        payload.setAttribute("iv",Base64.encodeToString(iv, Base64.DEFAULT));
+        payload.setContent(Base64.encodeToString(ciphertext,Base64.DEFAULT));
+        return message;
+    }
+
+
+    public XmppAxolotlPlaintextMessage decrypt(AxolotlService.XmppAxolotlSession session, byte[] key) {
+        XmppAxolotlPlaintextMessage plaintextMessage = null;
+        try {
+
+            Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding");
+            SecretKeySpec keySpec = new SecretKeySpec(key, "AES");
+            IvParameterSpec ivSpec = new IvParameterSpec(iv);
+
+            cipher.init(Cipher.DECRYPT_MODE, keySpec, ivSpec);
+
+            String plaintext = new String(cipher.doFinal(ciphertext));
+            plaintextMessage = new XmppAxolotlPlaintextMessage(session, plaintext);
+
+        } catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException
+                | InvalidAlgorithmParameterException | IllegalBlockSizeException
+                | BadPaddingException e) {
+            throw new AssertionError(e);
+        }
+        return plaintextMessage;
+    }
 }

src/main/java/eu/siacs/conversations/entities/Account.java

@@ -20,6 +20,7 @@ import java.util.concurrent.CopyOnWriteArraySet;
 import eu.siacs.conversations.Config;
 import eu.siacs.conversations.R;
 import eu.siacs.conversations.crypto.OtrService;
+import eu.siacs.conversations.crypto.axolotl.AxolotlService;
 import eu.siacs.conversations.services.XmppConnectionService;
 import eu.siacs.conversations.xmpp.XmppConnection;
 import eu.siacs.conversations.xmpp.jid.InvalidJidException;
@@ -122,6 +123,7 @@ public class Account extends AbstractEntity {
 	protected String avatar;
 	protected boolean online = false;
 	private OtrService mOtrService = null;
+	private AxolotlService axolotlService = null;
 	private XmppConnection xmppConnection = null;
 	private long mEndGracePeriod = 0L;
 	private String otrFingerprint;
@@ -281,8 +283,13 @@ public class Account extends AbstractEntity {
 		return values;
 	}
 
+	public AxolotlService getAxolotlService() {
+		return axolotlService;
+	}
+
 	public void initAccountServices(final XmppConnectionService context) {
 		this.mOtrService = new OtrService(context, this);
+		this.axolotlService = new AxolotlService(this, context);
 	}
 
 	public OtrService getOtrService() {

src/main/java/eu/siacs/conversations/entities/Contact.java

@@ -2,6 +2,7 @@ package eu.siacs.conversations.entities;
 
 import android.content.ContentValues;
 import android.database.Cursor;
+import android.util.Base64;
 import android.util.Log;
 
 import org.json.JSONArray;
@@ -349,20 +350,38 @@ public class Contact implements ListItem, Blockable {
 		}
 	}
 
-	public List<IdentityKey> getTrustedAxolotlIdentityKeys() {
+	public List<IdentityKey> getAxolotlIdentityKeys() {
 		synchronized (this.keys) {
 			JSONArray serializedKeyItems = this.keys.optJSONArray("axolotl_identity_key");
 			List<IdentityKey> identityKeys = new ArrayList<>();
+			List<Integer> toDelete = new ArrayList<>();
 			if(serializedKeyItems != null) {
 				for(int i = 0; i<serializedKeyItems.length();++i) {
 					try {
 						String serializedKeyItem = serializedKeyItems.getString(i);
-						IdentityKey identityKey = new IdentityKey(serializedKeyItem.getBytes(), 0);
+						IdentityKey identityKey = new IdentityKey(Base64.decode(serializedKeyItem, Base64.DEFAULT), 0);
 						identityKeys.add(identityKey);
 					} catch (InvalidKeyException e) {
-						Log.e(Config.LOGTAG, "Invalid axolotl identity key encountered at" + this.getJid() + ": " + e.getMessage());
+						Log.e(Config.LOGTAG, "Invalid axolotl identity key encountered at contact" + this.getJid() + ": " + e.getMessage() + ", marking for deletion...");
+						toDelete.add(i);
 					} catch (JSONException e) {
-						Log.e(Config.LOGTAG, "Error retrieving axolotl identity key at" + this.getJid() + ": " + e.getMessage());
+						Log.e(Config.LOGTAG, "Error retrieving axolotl identity key at contact " + this.getJid() + ": " + e.getMessage());
+					} catch (IllegalArgumentException e) {
+						Log.e(Config.LOGTAG, "Encountered malformed identity key for contact" + this.getJid() + ": " + e.getMessage() + ", marking for deletion... ");
+						toDelete.add(i);
+					}
+				}
+				if(!toDelete.isEmpty()) {
+					try {
+						JSONArray filteredKeyItems = new JSONArray();
+						for (int i = 0; i < serializedKeyItems.length(); ++i) {
+							if (!toDelete.contains(i)) {
+								filteredKeyItems.put(serializedKeyItems.get(i));
+							}
+						}
+						this.keys.put("axolotl_identity_key", filteredKeyItems);
+					} catch (JSONException e) {
+						//should never happen
 					}
 				}
 			}
@@ -370,23 +389,28 @@ public class Contact implements ListItem, Blockable {
 		}
 	}
 
-	public boolean addAxolotlIdentityKey(IdentityKey identityKey, boolean trusted) {
+	public boolean addAxolotlIdentityKey(IdentityKey identityKey) {
 		synchronized (this.keys) {
+			if(!getAxolotlIdentityKeys().contains(identityKey)) {
                 JSONArray keysList;
                 try {
                     keysList = this.keys.getJSONArray("axolotl_identity_key");
                 } catch (JSONException e) {
                     keysList = new JSONArray();
                 }
-			keysList.put(new String(identityKey.serialize()));
+
+				keysList.put(Base64.encodeToString(identityKey.serialize(), Base64.DEFAULT));
 				try {
 					this.keys.put("axolotl_identity_key", keysList);
 				} catch (JSONException e) {
 					Log.e(Config.LOGTAG, "Error adding Identity Key to Contact " + this.getJid() + ": " + e.getMessage());
 					return false;
 				}
-		}
                 return true;
+			} else {
+                return false;
+            }
+		}
 	}
 
 

src/main/java/eu/siacs/conversations/entities/Message.java

@@ -8,6 +8,7 @@ import java.net.URL;
 import java.util.Arrays;
 
 import eu.siacs.conversations.Config;
+import eu.siacs.conversations.crypto.axolotl.AxolotlService;
 import eu.siacs.conversations.utils.GeoHelper;
 import eu.siacs.conversations.utils.MimeUtils;
 import eu.siacs.conversations.utils.UIHelper;
@@ -34,6 +35,7 @@ public class Message extends AbstractEntity {
 	public static final int ENCRYPTION_OTR = 2;
 	public static final int ENCRYPTION_DECRYPTED = 3;
 	public static final int ENCRYPTION_DECRYPTION_FAILED = 4;
+	public static final int ENCRYPTION_AXOLOTL = 5;
 
 	public static final int TYPE_TEXT = 0;
 	public static final int TYPE_IMAGE = 1;
@@ -65,7 +67,7 @@ public class Message extends AbstractEntity {
 	protected int encryption;
 	protected int status;
 	protected int type;
-	private boolean isTrusted = true;
+	private AxolotlService.XmppAxolotlSession axolotlSession = null;
 	protected String relativeFilePath;
 	protected boolean read = true;
 	protected String remoteMsgId = null;
@@ -655,15 +657,7 @@ public class Message extends AbstractEntity {
 		public int height = 0;
 	}
 
-	public void trust() {
-		this.isTrusted = true;
-	}
-
-	public void distrust() {
-		this.isTrusted = false;
-	}
-
 	public boolean isTrusted() {
-		return this.isTrusted;
+		return this.axolotlSession != null && this.axolotlSession.isTrusted();
 	}
 }

src/main/java/eu/siacs/conversations/persistance/DatabaseBackend.java

@@ -1,5 +1,19 @@
 package eu.siacs.conversations.persistance;
 
+import android.content.ContentValues;
+import android.content.Context;
+import android.database.Cursor;
+import android.database.sqlite.SQLiteCantOpenDatabaseException;
+import android.database.sqlite.SQLiteDatabase;
+import android.database.sqlite.SQLiteOpenHelper;
+import android.util.Base64;
+import android.util.Log;
+
+import org.whispersystems.libaxolotl.AxolotlAddress;
+import org.whispersystems.libaxolotl.state.PreKeyRecord;
+import org.whispersystems.libaxolotl.state.SessionRecord;
+import org.whispersystems.libaxolotl.state.SignedPreKeyRecord;
+
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
@@ -15,25 +29,12 @@ import eu.siacs.conversations.entities.Roster;
 import eu.siacs.conversations.xmpp.jid.InvalidJidException;
 import eu.siacs.conversations.xmpp.jid.Jid;
 
-import android.content.ContentValues;
-import android.content.Context;
-import android.database.Cursor;
-import android.database.sqlite.SQLiteCantOpenDatabaseException;
-import android.database.sqlite.SQLiteDatabase;
-import android.database.sqlite.SQLiteOpenHelper;
-import android.util.Log;
-
-import org.whispersystems.libaxolotl.AxolotlAddress;
-import org.whispersystems.libaxolotl.state.PreKeyRecord;
-import org.whispersystems.libaxolotl.state.SessionRecord;
-import org.whispersystems.libaxolotl.state.SignedPreKeyRecord;
-
 public class DatabaseBackend extends SQLiteOpenHelper {
 
 	private static DatabaseBackend instance = null;
 
 	private static final String DATABASE_NAME = "history";
-	private static final int DATABASE_VERSION = 14;
+	private static final int DATABASE_VERSION = 15;
 
 	private static String CREATE_CONTATCS_STATEMENT = "create table "
 			+ Contact.TABLENAME + "(" + Contact.ACCOUNT + " TEXT, "
@@ -49,8 +50,9 @@ public class DatabaseBackend extends SQLiteOpenHelper {
 
 	private static String CREATE_PREKEYS_STATEMENT = "CREATE TABLE "
 			+ AxolotlService.SQLiteAxolotlStore.PREKEY_TABLENAME + "("
+				+ AxolotlService.SQLiteAxolotlStore.ACCOUNT + " TEXT,  "
 				+ AxolotlService.SQLiteAxolotlStore.ID + " INTEGER, "
-				+ AxolotlService.SQLiteAxolotlStore.KEY + "TEXT, FOREIGN KEY("
+				+ AxolotlService.SQLiteAxolotlStore.KEY + " TEXT, FOREIGN KEY("
 					+ AxolotlService.SQLiteAxolotlStore.ACCOUNT
 				+ ") REFERENCES " + Account.TABLENAME + "(" + Account.UUID + ") ON DELETE CASCADE, "
 				+ "UNIQUE( " + AxolotlService.SQLiteAxolotlStore.ACCOUNT + ", "
@@ -60,8 +62,9 @@ public class DatabaseBackend extends SQLiteOpenHelper {
 
 	private static String CREATE_SIGNED_PREKEYS_STATEMENT = "CREATE TABLE "
 			+ AxolotlService.SQLiteAxolotlStore.SIGNED_PREKEY_TABLENAME + "("
+				+ AxolotlService.SQLiteAxolotlStore.ACCOUNT + " TEXT,  "
 				+ AxolotlService.SQLiteAxolotlStore.ID + " INTEGER, "
-				+ AxolotlService.SQLiteAxolotlStore.KEY + "TEXT, FOREIGN KEY("
+				+ AxolotlService.SQLiteAxolotlStore.KEY + " TEXT, FOREIGN KEY("
 					+ AxolotlService.SQLiteAxolotlStore.ACCOUNT
 				+ ") REFERENCES " + Account.TABLENAME + "(" + Account.UUID + ") ON DELETE CASCADE, "
 				+ "UNIQUE( " + AxolotlService.SQLiteAxolotlStore.ACCOUNT + ", "
@@ -71,13 +74,16 @@ public class DatabaseBackend extends SQLiteOpenHelper {
 
 	private static String CREATE_SESSIONS_STATEMENT = "CREATE TABLE "
 			+ AxolotlService.SQLiteAxolotlStore.SESSION_TABLENAME + "("
+				+ AxolotlService.SQLiteAxolotlStore.ACCOUNT + " TEXT,  "
                 + AxolotlService.SQLiteAxolotlStore.NAME + " TEXT, "
-                + AxolotlService.SQLiteAxolotlStore.DEVICE_ID+ " INTEGER, "
+                + AxolotlService.SQLiteAxolotlStore.DEVICE_ID + " INTEGER, "
-                + AxolotlService.SQLiteAxolotlStore.KEY + "TEXT, FOREIGN KEY("
+				+ AxolotlService.SQLiteAxolotlStore.TRUSTED + " INTEGER, "
+                + AxolotlService.SQLiteAxolotlStore.KEY + " TEXT, FOREIGN KEY("
                     + AxolotlService.SQLiteAxolotlStore.ACCOUNT
 				+ ") REFERENCES " + Account.TABLENAME + "(" + Account.UUID + ") ON DELETE CASCADE, "
                 + "UNIQUE( " + AxolotlService.SQLiteAxolotlStore.ACCOUNT + ", "
-                    + AxolotlService.SQLiteAxolotlStore.NAME
+                    + AxolotlService.SQLiteAxolotlStore.NAME + ", "
+					+ AxolotlService.SQLiteAxolotlStore.DEVICE_ID
 				+ ") ON CONFLICT REPLACE"
 			+");";
 
@@ -257,6 +263,14 @@ public class DatabaseBackend extends SQLiteOpenHelper {
 			}
 			cursor.close();
 		}
+		if (oldVersion < 15  && newVersion >= 15) {
+			db.execSQL("DROP TABLE IF EXISTS " + AxolotlService.SQLiteAxolotlStore.SESSION_TABLENAME);
+			db.execSQL(CREATE_SESSIONS_STATEMENT);
+			db.execSQL("DROP TABLE IF EXISTS " + AxolotlService.SQLiteAxolotlStore.PREKEY_TABLENAME);
+			db.execSQL(CREATE_PREKEYS_STATEMENT);
+			db.execSQL("DROP TABLE IF EXISTS " + AxolotlService.SQLiteAxolotlStore.SIGNED_PREKEY_TABLENAME);
+			db.execSQL(CREATE_SIGNED_PREKEYS_STATEMENT);
+		}
 	}
 
 	public static synchronized DatabaseBackend getInstance(Context context) {
@@ -547,7 +561,7 @@ public class DatabaseBackend extends SQLiteOpenHelper {
 		if(cursor.getCount() != 0) {
 			cursor.moveToFirst();
 			try {
-				session = new SessionRecord(cursor.getString(cursor.getColumnIndex(AxolotlService.SQLiteAxolotlStore.KEY)).getBytes());
+				session = new SessionRecord(Base64.decode(cursor.getString(cursor.getColumnIndex(AxolotlService.SQLiteAxolotlStore.KEY)),Base64.DEFAULT));
 			} catch (IOException e) {
 				throw new AssertionError(e);
 			}
@@ -590,7 +604,7 @@ public class DatabaseBackend extends SQLiteOpenHelper {
 		ContentValues values = new ContentValues();
 		values.put(AxolotlService.SQLiteAxolotlStore.NAME, contact.getName());
 		values.put(AxolotlService.SQLiteAxolotlStore.DEVICE_ID, contact.getDeviceId());
-		values.put(AxolotlService.SQLiteAxolotlStore.KEY, session.serialize());
+		values.put(AxolotlService.SQLiteAxolotlStore.KEY, Base64.encodeToString(session.serialize(),Base64.DEFAULT));
 		values.put(AxolotlService.SQLiteAxolotlStore.ACCOUNT, account.getUuid());
 		db.insert(AxolotlService.SQLiteAxolotlStore.SESSION_TABLENAME, null, values);
 	}
@@ -616,6 +630,28 @@ public class DatabaseBackend extends SQLiteOpenHelper {
 				args);
 	}
 
+	public boolean isTrustedSession(Account account, AxolotlAddress contact) {
+		boolean trusted = false;
+		Cursor cursor = getCursorForSession(account, contact);
+		if(cursor.getCount() != 0) {
+			cursor.moveToFirst();
+            trusted = cursor.getInt(cursor.getColumnIndex(
+					AxolotlService.SQLiteAxolotlStore.TRUSTED)) > 0;
+		}
+		cursor.close();
+		return trusted;
+	}
+
+	public void setTrustedSession(Account account, AxolotlAddress contact, boolean trusted) {
+		SQLiteDatabase db = this.getWritableDatabase();
+		ContentValues values = new ContentValues();
+		values.put(AxolotlService.SQLiteAxolotlStore.NAME, contact.getName());
+		values.put(AxolotlService.SQLiteAxolotlStore.DEVICE_ID, contact.getDeviceId());
+		values.put(AxolotlService.SQLiteAxolotlStore.ACCOUNT, account.getUuid());
+		values.put(AxolotlService.SQLiteAxolotlStore.TRUSTED, trusted?1:0);
+		db.insert(AxolotlService.SQLiteAxolotlStore.SESSION_TABLENAME, null, values);
+	}
+
 	private Cursor getCursorForPreKey(Account account, int preKeyId) {
 		SQLiteDatabase db = this.getReadableDatabase();
 		String[] columns = {AxolotlService.SQLiteAxolotlStore.KEY};
@@ -636,7 +672,7 @@ public class DatabaseBackend extends SQLiteOpenHelper {
 		if(cursor.getCount() != 0) {
 			cursor.moveToFirst();
 			try {
-				record = new PreKeyRecord(cursor.getString(cursor.getColumnIndex(AxolotlService.SQLiteAxolotlStore.KEY)).getBytes());
+				record = new PreKeyRecord(Base64.decode(cursor.getString(cursor.getColumnIndex(AxolotlService.SQLiteAxolotlStore.KEY)),Base64.DEFAULT));
 			} catch (IOException e ) {
 				throw new AssertionError(e);
 			}
@@ -656,7 +692,7 @@ public class DatabaseBackend extends SQLiteOpenHelper {
 		SQLiteDatabase db = this.getWritableDatabase();
 		ContentValues values = new ContentValues();
 		values.put(AxolotlService.SQLiteAxolotlStore.ID, record.getId());
-		values.put(AxolotlService.SQLiteAxolotlStore.KEY, record.serialize());
+		values.put(AxolotlService.SQLiteAxolotlStore.KEY, Base64.encodeToString(record.serialize(),Base64.DEFAULT));
 		values.put(AxolotlService.SQLiteAxolotlStore.ACCOUNT, account.getUuid());
 		db.insert(AxolotlService.SQLiteAxolotlStore.PREKEY_TABLENAME, null, values);
 	}
@@ -685,11 +721,11 @@ public class DatabaseBackend extends SQLiteOpenHelper {
 
 	public SignedPreKeyRecord loadSignedPreKey(Account account, int signedPreKeyId) {
 		SignedPreKeyRecord record = null;
-		Cursor cursor = getCursorForPreKey(account, signedPreKeyId);
+		Cursor cursor = getCursorForSignedPreKey(account, signedPreKeyId);
 		if(cursor.getCount() != 0) {
 			cursor.moveToFirst();
 			try {
-				record = new SignedPreKeyRecord(cursor.getString(cursor.getColumnIndex(AxolotlService.SQLiteAxolotlStore.KEY)).getBytes());
+				record = new SignedPreKeyRecord(Base64.decode(cursor.getString(cursor.getColumnIndex(AxolotlService.SQLiteAxolotlStore.KEY)),Base64.DEFAULT));
 			} catch (IOException e ) {
 				throw new AssertionError(e);
 			}
@@ -711,7 +747,7 @@ public class DatabaseBackend extends SQLiteOpenHelper {
 
 		while(cursor.moveToNext()) {
 			try {
-				prekeys.add(new SignedPreKeyRecord(cursor.getString(cursor.getColumnIndex(AxolotlService.SQLiteAxolotlStore.KEY)).getBytes()));
+				prekeys.add(new SignedPreKeyRecord(Base64.decode(cursor.getString(cursor.getColumnIndex(AxolotlService.SQLiteAxolotlStore.KEY)), Base64.DEFAULT)));
 			} catch (IOException ignored) {
 			}
 		}
@@ -729,7 +765,7 @@ public class DatabaseBackend extends SQLiteOpenHelper {
 		SQLiteDatabase db = this.getWritableDatabase();
 		ContentValues values = new ContentValues();
 		values.put(AxolotlService.SQLiteAxolotlStore.ID, record.getId());
-		values.put(AxolotlService.SQLiteAxolotlStore.KEY, record.serialize());
+		values.put(AxolotlService.SQLiteAxolotlStore.KEY, Base64.encodeToString(record.serialize(),Base64.DEFAULT));
 		values.put(AxolotlService.SQLiteAxolotlStore.ACCOUNT, account.getUuid());
 		db.insert(AxolotlService.SQLiteAxolotlStore.SIGNED_PREKEY_TABLENAME, null, values);
 	}

src/main/java/eu/siacs/conversations/services/XmppConnectionService.java

@@ -52,6 +52,7 @@ import de.duenndns.ssl.MemorizingTrustManager;
 import eu.siacs.conversations.Config;
 import eu.siacs.conversations.R;
 import eu.siacs.conversations.crypto.PgpEngine;
+import eu.siacs.conversations.crypto.axolotl.NoSessionsCreatedException;
 import eu.siacs.conversations.entities.Account;
 import eu.siacs.conversations.entities.Blockable;
 import eu.siacs.conversations.entities.Bookmark;
@@ -272,7 +273,11 @@ public class XmppConnectionService extends Service implements OnPhoneContactsLoa
 					}
 				}
 				syncDirtyContacts(account);
-				scheduleWakeUpCall(Config.PING_MAX_INTERVAL,account.getUuid().hashCode());
+                account.getAxolotlService().publishOwnDeviceIdIfNeeded();
+                account.getAxolotlService().publishBundleIfNeeded();
+                account.getAxolotlService().publishPreKeysIfNeeded();
+
+				scheduleWakeUpCall(Config.PING_MAX_INTERVAL, account.getUuid().hashCode());
 			} else if (account.getStatus() == Account.State.OFFLINE) {
 				resetSendingToWaiting(account);
 				if (!account.isOptionSet(Account.OPTION_DISABLED)) {