integrate trust manager into conversations

8 files changed, 1064 insertions, 6 deletions

diff --git a/src/main/java/de/pixart/messenger/crypto/DomainHostnameVerifier.java b/src/main/java/de/pixart/messenger/crypto/DomainHostnameVerifier.java
new file mode 100644
index 000000000..0ceb650f3
--- /dev/null
+++ b/src/main/java/de/pixart/messenger/crypto/DomainHostnameVerifier.java
@@ -0,0 +1,10 @@
+package de.pixart.messenger.crypto;
+
+import javax.net.ssl.HostnameVerifier;
+import javax.net.ssl.SSLSession;
+
+public interface DomainHostnameVerifier extends HostnameVerifier {
+
+    boolean verify(String domain, String hostname, SSLSession sslSession);
+
+}
\ No newline at end of file
diff --git a/src/main/java/de/pixart/messenger/crypto/XmppDomainVerifier.java b/src/main/java/de/pixart/messenger/crypto/XmppDomainVerifier.java
index e811a0f39..3f3c358a7 100644
--- a/src/main/java/de/pixart/messenger/crypto/XmppDomainVerifier.java
+++ b/src/main/java/de/pixart/messenger/crypto/XmppDomainVerifier.java
@@ -25,8 +25,6 @@ import java.util.List;
 
 import javax.net.ssl.SSLSession;
 
-import de.duenndns.ssl.DomainHostnameVerifier;
-
 public class XmppDomainVerifier implements DomainHostnameVerifier {
 
     private static final String LOGTAG = "XmppDomainVerifier";
diff --git a/src/main/java/de/pixart/messenger/entities/MTMDecision.java b/src/main/java/de/pixart/messenger/entities/MTMDecision.java
new file mode 100644
index 000000000..38cc4b578
--- /dev/null
+++ b/src/main/java/de/pixart/messenger/entities/MTMDecision.java
@@ -0,0 +1,33 @@
+/* MemorizingTrustManager - a TrustManager which asks the user about invalid
+ *  certificates and memorizes their decision.
+ *
+ * Copyright (c) 2010 Georg Lukas <georg@op-co.de>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package de.pixart.messenger.entities;
+
+public class MTMDecision {
+    public final static int DECISION_INVALID	= 0;
+    public final static int DECISION_ABORT		= 1;
+    public final static int DECISION_ONCE		= 2;
+    public final static int DECISION_ALWAYS	= 3;
+
+    public int state = DECISION_INVALID;
+}
\ No newline at end of file
diff --git a/src/main/java/de/pixart/messenger/services/MemorizingTrustManager.java b/src/main/java/de/pixart/messenger/services/MemorizingTrustManager.java
new file mode 100644
index 000000000..aacaaaad8
--- /dev/null
+++ b/src/main/java/de/pixart/messenger/services/MemorizingTrustManager.java
@@ -0,0 +1,899 @@
+/* MemorizingTrustManager - a TrustManager which asks the user about invalid
+ *  certificates and memorizes their decision.
+ *
+ * Copyright (c) 2010 Georg Lukas <georg@op-co.de>
+ *
+ * MemorizingTrustManager.java contains the actual trust manager and interface
+ * code to create a MemorizingActivity and obtain the results.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package de.pixart.messenger.services;
+
+import android.app.Activity;
+import android.app.Application;
+import android.app.NotificationManager;
+import android.app.Service;
+import android.content.Context;
+import android.content.Intent;
+import android.net.Uri;
+import android.preference.PreferenceManager;
+import android.util.Base64;
+import android.util.Log;
+import android.util.SparseArray;
+import android.os.Handler;
+
+import org.json.JSONArray;
+import org.json.JSONException;
+import org.json.JSONObject;
+
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.net.URL;
+import java.security.NoSuchAlgorithmException;
+import java.security.cert.*;
+import java.security.KeyStore;
+import java.security.KeyStoreException;
+import java.security.MessageDigest;
+import java.util.ArrayList;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+import java.text.SimpleDateFormat;
+import java.util.Collection;
+import java.util.Enumeration;
+import java.util.List;
+import java.util.Locale;
+import java.util.regex.Pattern;
+
+import javax.net.ssl.HostnameVerifier;
+import javax.net.ssl.HttpsURLConnection;
+import javax.net.ssl.SSLSession;
+import javax.net.ssl.TrustManager;
+import javax.net.ssl.TrustManagerFactory;
+import javax.net.ssl.X509TrustManager;
+
+import de.pixart.messenger.R;
+import de.pixart.messenger.crypto.DomainHostnameVerifier;
+import de.pixart.messenger.entities.MTMDecision;
+import de.pixart.messenger.ui.MemorizingActivity;
+
+/**
+ * A X509 trust manager implementation which asks the user about invalid
+ * certificates and memorizes their decision.
+ * <p>
+ * The certificate validity is checked using the system default X509
+ * TrustManager, creating a query Dialog if the check fails.
+ * <p>
+ * <b>WARNING:</b> This only works if a dedicated thread is used for
+ * opening sockets!
+ */
+public class MemorizingTrustManager {
+
+
+    private static final Pattern PATTERN_IPV4 = Pattern.compile("\\A(25[0-5]|2[0-4]\\d|[0-1]?\\d?\\d)(\\.(25[0-5]|2[0-4]\\d|[0-1]?\\d?\\d)){3}\\z");
+    private static final Pattern PATTERN_IPV6_HEX4DECCOMPRESSED = Pattern.compile("\\A((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4})*)?) ::((?:[0-9A-Fa-f]{1,4}:)*)(25[0-5]|2[0-4]\\d|[0-1]?\\d?\\d)(\\.(25[0-5]|2[0-4]\\d|[0-1]?\\d?\\d)){3}\\z");
+    private static final Pattern PATTERN_IPV6_6HEX4DEC = Pattern.compile("\\A((?:[0-9A-Fa-f]{1,4}:){6,6})(25[0-5]|2[0-4]\\d|[0-1]?\\d?\\d)(\\.(25[0-5]|2[0-4]\\d|[0-1]?\\d?\\d)){3}\\z");
+    private static final Pattern PATTERN_IPV6_HEXCOMPRESSED = Pattern.compile("\\A((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4})*)?)::((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4})*)?)\\z");
+    private static final Pattern PATTERN_IPV6 = Pattern.compile("\\A(?:[0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}\\z");
+
+    final static String DECISION_INTENT = "de.duenndns.ssl.DECISION";
+    public final static String DECISION_INTENT_ID     = DECISION_INTENT + ".decisionId";
+    public final static String DECISION_INTENT_CERT   = DECISION_INTENT + ".cert";
+    final static String DECISION_INTENT_CHOICE = DECISION_INTENT + ".decisionChoice";
+
+    private final static Logger LOGGER = Logger.getLogger(MemorizingTrustManager.class.getName());
+    public final static String DECISION_TITLE_ID      = DECISION_INTENT + ".titleId";
+    private final static int NOTIFICATION_ID = 100509;
+
+    final static String NO_TRUST_ANCHOR = "Trust anchor for certification path not found.";
+
+    static String KEYSTORE_DIR = "KeyStore";
+    static String KEYSTORE_FILE = "KeyStore.bks";
+
+    Context master;
+    Activity foregroundAct;
+    NotificationManager notificationManager;
+    private static int decisionId = 0;
+    private static SparseArray<MTMDecision> openDecisions = new SparseArray<MTMDecision>();
+
+    Handler masterHandler;
+    private File keyStoreFile;
+    private KeyStore appKeyStore;
+    private X509TrustManager defaultTrustManager;
+    private X509TrustManager appTrustManager;
+    private String poshCacheDir;
+
+    /** Creates an instance of the MemorizingTrustManager class that falls back to a custom TrustManager.
+     *
+     * You need to supply the application context. This has to be one of:
+     *    - Application
+     *    - Activity
+     *    - Service
+     *
+     * The context is used for file management, to display the dialog /
+     * notification and for obtaining translated strings.
+     *
+     * @param m Context for the application.
+     * @param defaultTrustManager Delegate trust management to this TM. If null, the user must accept every certificate.
+     */
+    public MemorizingTrustManager(Context m, X509TrustManager defaultTrustManager) {
+        init(m);
+        this.appTrustManager = getTrustManager(appKeyStore);
+        this.defaultTrustManager = defaultTrustManager;
+    }
+
+    /** Creates an instance of the MemorizingTrustManager class using the system X509TrustManager.
+     *
+     * You need to supply the application context. This has to be one of:
+     *    - Application
+     *    - Activity
+     *    - Service
+     *
+     * The context is used for file management, to display the dialog /
+     * notification and for obtaining translated strings.
+     *
+     * @param m Context for the application.
+     */
+    public MemorizingTrustManager(Context m) {
+        init(m);
+        this.appTrustManager = getTrustManager(appKeyStore);
+        this.defaultTrustManager = getTrustManager(null);
+    }
+
+    void init(Context m) {
+        master = m;
+        masterHandler = new Handler(m.getMainLooper());
+        notificationManager = (NotificationManager)master.getSystemService(Context.NOTIFICATION_SERVICE);
+
+        Application app;
+        if (m instanceof Application) {
+            app = (Application)m;
+        } else if (m instanceof Service) {
+            app = ((Service)m).getApplication();
+        } else if (m instanceof Activity) {
+            app = ((Activity)m).getApplication();
+        } else throw new ClassCastException("MemorizingTrustManager context must be either Activity or Service!");
+
+        File dir = app.getDir(KEYSTORE_DIR, Context.MODE_PRIVATE);
+        keyStoreFile = new File(dir + File.separator + KEYSTORE_FILE);
+
+        poshCacheDir = app.getFilesDir().getAbsolutePath()+"/posh_cache/";
+
+        appKeyStore = loadAppKeyStore();
+    }
+
+
+    /**
+     * Binds an Activity to the MTM for displaying the query dialog.
+     *
+     * This is useful if your connection is run from a service that is
+     * triggered by user interaction -- in such cases the activity is
+     * visible and the user tends to ignore the service notification.
+     *
+     * You should never have a hidden activity bound to MTM! Use this
+     * function in onResume() and @see unbindDisplayActivity in onPause().
+     *
+     * @param act Activity to be bound
+     */
+    public void bindDisplayActivity(Activity act) {
+        foregroundAct = act;
+    }
+
+    /**
+     * Removes an Activity from the MTM display stack.
+     *
+     * Always call this function when the Activity added with
+     * {@link #bindDisplayActivity(Activity)} is hidden.
+     *
+     * @param act Activity to be unbound
+     */
+    public void unbindDisplayActivity(Activity act) {
+        // do not remove if it was overridden by a different activity
+        if (foregroundAct == act)
+            foregroundAct = null;
+    }
+
+    /**
+     * Changes the path for the KeyStore file.
+     *
+     * The actual filename relative to the app's directory will be
+     * <code>app_<i>dirname</i>/<i>filename</i></code>.
+     *
+     * @param dirname directory to store the KeyStore.
+     * @param filename file name for the KeyStore.
+     */
+    public static void setKeyStoreFile(String dirname, String filename) {
+        KEYSTORE_DIR = dirname;
+        KEYSTORE_FILE = filename;
+    }
+
+    /**
+     * Get a list of all certificate aliases stored in MTM.
+     *
+     * @return an {@link Enumeration} of all certificates
+     */
+    public Enumeration<String> getCertificates() {
+        try {
+            return appKeyStore.aliases();
+        } catch (KeyStoreException e) {
+            // this should never happen, however...
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * Get a certificate for a given alias.
+     *
+     * @param alias the certificate's alias as returned by {@link #getCertificates()}.
+     *
+     * @return the certificate associated with the alias or <tt>null</tt> if none found.
+     */
+    public Certificate getCertificate(String alias) {
+        try {
+            return appKeyStore.getCertificate(alias);
+        } catch (KeyStoreException e) {
+            // this should never happen, however...
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * Removes the given certificate from MTMs key store.
+     *
+     * <p>
+     * <b>WARNING</b>: this does not immediately invalidate the certificate. It is
+     * well possible that (a) data is transmitted over still existing connections or
+     * (b) new connections are created using TLS renegotiation, without a new cert
+     * check.
+     * </p>
+     * @param alias the certificate's alias as returned by {@link #getCertificates()}.
+     *
+     * @throws KeyStoreException if the certificate could not be deleted.
+     */
+    public void deleteCertificate(String alias) throws KeyStoreException {
+        appKeyStore.deleteEntry(alias);
+        keyStoreUpdated();
+    }
+
+    /**
+     * Creates a new hostname verifier supporting user interaction.
+     *
+     * <p>This method creates a new {@link HostnameVerifier} that is bound to
+     * the given instance of {@link MemorizingTrustManager}, and leverages an
+     * existing {@link HostnameVerifier}. The returned verifier performs the
+     * following steps, returning as soon as one of them succeeds:
+     *  </p>
+     *  <ol>
+     *  <li>Success, if the wrapped defaultVerifier accepts the certificate.</li>
+     *  <li>Success, if the server certificate is stored in the keystore under the given hostname.</li>
+     *  <li>Ask the user and return accordingly.</li>
+     *  <li>Failure on exception.</li>
+     *  </ol>
+     *
+     * @param defaultVerifier the {@link HostnameVerifier} that should perform the actual check
+     * @return a new hostname verifier using the MTM's key store
+     *
+     * @throws IllegalArgumentException if the defaultVerifier parameter is null
+     */
+    public DomainHostnameVerifier wrapHostnameVerifier(final HostnameVerifier defaultVerifier, final boolean interactive) {
+        if (defaultVerifier == null)
+            throw new IllegalArgumentException("The default verifier may not be null");
+
+        return new MemorizingHostnameVerifier(defaultVerifier, interactive);
+    }
+
+    X509TrustManager getTrustManager(KeyStore ks) {
+        try {
+            TrustManagerFactory tmf = TrustManagerFactory.getInstance("X509");
+            tmf.init(ks);
+            for (TrustManager t : tmf.getTrustManagers()) {
+                if (t instanceof X509TrustManager) {
+                    return (X509TrustManager)t;
+                }
+            }
+        } catch (Exception e) {
+            // Here, we are covering up errors. It might be more useful
+            // however to throw them out of the constructor so the
+            // embedding app knows something went wrong.
+            LOGGER.log(Level.SEVERE, "getTrustManager(" + ks + ")", e);
+        }
+        return null;
+    }
+
+    KeyStore loadAppKeyStore() {
+        KeyStore ks;
+        try {
+            ks = KeyStore.getInstance(KeyStore.getDefaultType());
+        } catch (KeyStoreException e) {
+            LOGGER.log(Level.SEVERE, "getAppKeyStore()", e);
+            return null;
+        }
+        try {
+            ks.load(null, null);
+            ks.load(new java.io.FileInputStream(keyStoreFile), "MTM".toCharArray());
+        } catch (java.io.FileNotFoundException e) {
+            LOGGER.log(Level.INFO, "getAppKeyStore(" + keyStoreFile + ") - file does not exist");
+        } catch (Exception e) {
+            LOGGER.log(Level.SEVERE, "getAppKeyStore(" + keyStoreFile + ")", e);
+        }
+        return ks;
+    }
+
+    void storeCert(String alias, Certificate cert) {
+        try {
+            appKeyStore.setCertificateEntry(alias, cert);
+        } catch (KeyStoreException e) {
+            LOGGER.log(Level.SEVERE, "storeCert(" + cert + ")", e);
+            return;
+        }
+        keyStoreUpdated();
+    }
+
+    void storeCert(X509Certificate cert) {
+        storeCert(cert.getSubjectDN().toString(), cert);
+    }
+
+    void keyStoreUpdated() {
+        // reload appTrustManager
+        appTrustManager = getTrustManager(appKeyStore);
+
+        // store KeyStore to file
+        java.io.FileOutputStream fos = null;
+        try {
+            fos = new java.io.FileOutputStream(keyStoreFile);
+            appKeyStore.store(fos, "MTM".toCharArray());
+        } catch (Exception e) {
+            LOGGER.log(Level.SEVERE, "storeCert(" + keyStoreFile + ")", e);
+        } finally {
+            if (fos != null) {
+                try {
+                    fos.close();
+                } catch (IOException e) {
+                    LOGGER.log(Level.SEVERE, "storeCert(" + keyStoreFile + ")", e);
+                }
+            }
+        }
+    }
+
+    // if the certificate is stored in the app key store, it is considered "known"
+    private boolean isCertKnown(X509Certificate cert) {
+        try {
+            return appKeyStore.getCertificateAlias(cert) != null;
+        } catch (KeyStoreException e) {
+            return false;
+        }
+    }
+
+    private boolean isExpiredException(Throwable e) {
+        do {
+            if (e instanceof CertificateExpiredException)
+                return true;
+            e = e.getCause();
+        } while (e != null);
+        return false;
+    }
+
+    public void checkCertTrusted(X509Certificate[] chain, String authType, String domain, boolean isServer, boolean interactive)
+            throws CertificateException
+    {
+        LOGGER.log(Level.FINE, "checkCertTrusted(" + chain + ", " + authType + ", " + isServer + ")");
+        try {
+            LOGGER.log(Level.FINE, "checkCertTrusted: trying appTrustManager");
+            if (isServer)
+                appTrustManager.checkServerTrusted(chain, authType);
+            else
+                appTrustManager.checkClientTrusted(chain, authType);
+        } catch (CertificateException ae) {
+            LOGGER.log(Level.FINER, "checkCertTrusted: appTrustManager failed", ae);
+            // if the cert is stored in our appTrustManager, we ignore expiredness
+            if (isExpiredException(ae)) {
+                LOGGER.log(Level.INFO, "checkCertTrusted: accepting expired certificate from keystore");
+                return;
+            }
+            if (isCertKnown(chain[0])) {
+                LOGGER.log(Level.INFO, "checkCertTrusted: accepting cert already stored in keystore");
+                return;
+            }
+            try {
+                if (defaultTrustManager == null)
+                    throw ae;
+                LOGGER.log(Level.FINE, "checkCertTrusted: trying defaultTrustManager");
+                if (isServer)
+                    defaultTrustManager.checkServerTrusted(chain, authType);
+                else
+                    defaultTrustManager.checkClientTrusted(chain, authType);
+            } catch (CertificateException e) {
+                boolean trustSystemCAs = !PreferenceManager.getDefaultSharedPreferences(master).getBoolean("dont_trust_system_cas", false);
+                if (domain != null && isServer && trustSystemCAs && !isIp(domain)) {
+                    String hash = getBase64Hash(chain[0],"SHA-256");
+                    List<String> fingerprints = getPoshFingerprints(domain);
+                    if (hash != null && fingerprints.contains(hash)) {
+                        Log.d("mtm","trusted cert fingerprint of "+domain+" via posh");
+                        return;
+                    }
+                }
+                e.printStackTrace();
+                if (interactive) {
+                    interactCert(chain, authType, e);
+                } else {
+                    throw e;
+                }
+            }
+        }
+    }
+
+    private List<String> getPoshFingerprints(String domain) {
+        List<String> cached = getPoshFingerprintsFromCache(domain);
+        if (cached == null) {
+            return getPoshFingerprintsFromServer(domain);
+        } else {
+            return cached;
+        }
+    }
+
+    private List<String> getPoshFingerprintsFromServer(String domain) {
+        return getPoshFingerprintsFromServer(domain, "https://"+domain+"/.well-known/posh/xmpp-client.json",-1,true);
+    }
+
+    private List<String> getPoshFingerprintsFromServer(String domain, String url, int maxTtl, boolean followUrl) {
+        Log.d("mtm","downloading json for "+domain+" from "+url);
+        try {
+            List<String> results = new ArrayList<>();
+            HttpsURLConnection connection = (HttpsURLConnection) new URL(url).openConnection();
+            connection.setConnectTimeout(5000);
+            connection.setReadTimeout(5000);
+            BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
+            String inputLine;
+            StringBuilder builder = new StringBuilder();
+            while ((inputLine = in.readLine()) != null) {
+                builder.append(inputLine);
+            }
+            JSONObject jsonObject = new JSONObject(builder.toString());
+            in.close();
+            int expires = jsonObject.getInt("expires");
+            if (expires <= 0) {
+                return new ArrayList<>();
+            }
+            if (maxTtl >= 0) {
+                expires = Math.min(maxTtl,expires);
+            }
+            String redirect;
+            try {
+                redirect = jsonObject.getString("url");
+            } catch (JSONException e) {
+                redirect = null;
+            }
+            if (followUrl && redirect != null && redirect.toLowerCase().startsWith("https")) {
+                return getPoshFingerprintsFromServer(domain, redirect, expires, false);
+            }
+            JSONArray fingerprints = jsonObject.getJSONArray("fingerprints");
+            for(int i = 0; i < fingerprints.length(); i++) {
+                JSONObject fingerprint = fingerprints.getJSONObject(i);
+                String sha256 = fingerprint.getString("sha-256");
+                if (sha256 != null) {
+                    results.add(sha256);
+                }
+            }
+            writeFingerprintsToCache(domain, results,1000L * expires+System.currentTimeMillis());
+            return results;
+        } catch (Exception e) {
+            Log.d("mtm","error fetching posh "+e.getMessage());
+            return new ArrayList<>();
+        }
+    }
+
+    private File getPoshCacheFile(String domain) {
+        return new File(poshCacheDir+domain+".json");
+    }
+
+    private void writeFingerprintsToCache(String domain, List<String> results, long expires) {
+        File file = getPoshCacheFile(domain);
+        file.getParentFile().mkdirs();
+        try {
+            file.createNewFile();
+            JSONObject jsonObject = new JSONObject();
+            jsonObject.put("expires",expires);
+            jsonObject.put("fingerprints",new JSONArray(results));
+            FileOutputStream outputStream = new FileOutputStream(file);
+            outputStream.write(jsonObject.toString().getBytes());
+            outputStream.flush();
+            outputStream.close();
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+    }
+
+    private List<String> getPoshFingerprintsFromCache(String domain) {
+        File file = getPoshCacheFile(domain);
+        try {
+            InputStream is = new FileInputStream(file);
+            BufferedReader buf = new BufferedReader(new InputStreamReader(is));
+
+            String line = buf.readLine();
+            StringBuilder sb = new StringBuilder();
+
+            while(line != null){
+                sb.append(line).append("\n");
+                line = buf.readLine();
+            }
+            JSONObject jsonObject = new JSONObject(sb.toString());
+            is.close();
+            long expires = jsonObject.getLong("expires");
+            long expiresIn = expires - System.currentTimeMillis();
+            if (expiresIn < 0) {
+                file.delete();
+                return null;
+            } else {
+                Log.d("mtm","posh fingerprints expire in "+(expiresIn/1000)+"s");
+            }
+            List<String> result = new ArrayList<>();
+            JSONArray jsonArray = jsonObject.getJSONArray("fingerprints");
+            for(int i = 0; i < jsonArray.length(); ++i) {
+                result.add(jsonArray.getString(i));
+            }
+            return result;
+        } catch (FileNotFoundException e) {
+            return null;
+        } catch (IOException e) {
+            return null;
+        } catch (JSONException e) {
+            file.delete();
+            return null;
+        }
+    }
+
+    private static boolean isIp(final String server) {
+        return server != null && (
+                PATTERN_IPV4.matcher(server).matches()
+                        || PATTERN_IPV6.matcher(server).matches()
+                        || PATTERN_IPV6_6HEX4DEC.matcher(server).matches()
+                        || PATTERN_IPV6_HEX4DECCOMPRESSED.matcher(server).matches()
+                        || PATTERN_IPV6_HEXCOMPRESSED.matcher(server).matches());
+    }
+
+    private static String getBase64Hash(X509Certificate certificate, String digest) throws CertificateEncodingException {
+        MessageDigest md;
+        try {
+            md = MessageDigest.getInstance(digest);
+        } catch (NoSuchAlgorithmException e) {
+            return null;
+        }
+        md.update(certificate.getEncoded());
+        return Base64.encodeToString(md.digest(),Base64.NO_WRAP);
+    }
+
+    private X509Certificate[] getAcceptedIssuers() {
+        LOGGER.log(Level.FINE, "getAcceptedIssuers()");
+        return defaultTrustManager.getAcceptedIssuers();
+    }
+
+    private int createDecisionId(MTMDecision d) {
+        int myId;
+        synchronized(openDecisions) {
+            myId = decisionId;
+            openDecisions.put(myId, d);
+            decisionId += 1;
+        }
+        return myId;
+    }
+
+    private static String hexString(byte[] data) {
+        StringBuffer si = new StringBuffer();
+        for (int i = 0; i < data.length; i++) {
+            si.append(String.format("%02x", data[i]));
+            if (i < data.length - 1)
+                si.append(":");
+        }
+        return si.toString();
+    }
+
+    private static String certHash(final X509Certificate cert, String digest) {
+        try {
+            MessageDigest md = MessageDigest.getInstance(digest);
+            md.update(cert.getEncoded());
+            return hexString(md.digest());
+        } catch (java.security.cert.CertificateEncodingException e) {
+            return e.getMessage();
+        } catch (java.security.NoSuchAlgorithmException e) {
+            return e.getMessage();
+        }
+    }
+
+    private void certDetails(StringBuffer si, X509Certificate c) {
+        SimpleDateFormat validityDateFormater = new SimpleDateFormat("yyyy-MM-dd");
+        si.append("\n");
+        si.append(c.getSubjectDN().toString());
+        si.append("\n");
+        si.append(validityDateFormater.format(c.getNotBefore()));
+        si.append(" - ");
+        si.append(validityDateFormater.format(c.getNotAfter()));
+        si.append("\nSHA-256: ");
+        si.append(certHash(c, "SHA-256"));
+        si.append("\nSHA-1: ");
+        si.append(certHash(c, "SHA-1"));
+        si.append("\nSigned by: ");
+        si.append(c.getIssuerDN().toString());
+        si.append("\n");
+    }
+
+    private String certChainMessage(final X509Certificate[] chain, CertificateException cause) {
+        Throwable e = cause;
+        LOGGER.log(Level.FINE, "certChainMessage for " + e);
+        StringBuffer si = new StringBuffer();
+        if (e.getCause() != null) {
+            e = e.getCause();
+            // HACK: there is no sane way to check if the error is a "trust anchor
+            // not found", so we use string comparison.
+            if (NO_TRUST_ANCHOR.equals(e.getMessage())) {
+                si.append(master.getString(R.string.mtm_trust_anchor));
+            } else
+                si.append(e.getLocalizedMessage());
+            si.append("\n");
+        }
+        si.append("\n");
+        si.append(master.getString(R.string.mtm_connect_anyway));
+        si.append("\n\n");
+        si.append(master.getString(R.string.mtm_cert_details));
+        for (X509Certificate c : chain) {
+            certDetails(si, c);
+        }
+        return si.toString();
+    }
+
+    private String hostNameMessage(X509Certificate cert, String hostname) {
+        StringBuffer si = new StringBuffer();
+
+        si.append(master.getString(R.string.mtm_hostname_mismatch, hostname));
+        si.append("\n\n");
+        try {
+            Collection<List<?>> sans = cert.getSubjectAlternativeNames();
+            if (sans == null) {
+                si.append(cert.getSubjectDN());
+                si.append("\n");
+            } else for (List<?> altName : sans) {
+                Object name = altName.get(1);
+                if (name instanceof String) {
+                    si.append("[");
+                    si.append((Integer)altName.get(0));
+                    si.append("] ");
+                    si.append(name);
+                    si.append("\n");
+                }
+            }
+        } catch (CertificateParsingException e) {
+            e.printStackTrace();
+            si.append("<Parsing error: ");
+            si.append(e.getLocalizedMessage());
+            si.append(">\n");
+        }
+        si.append("\n");
+        si.append(master.getString(R.string.mtm_connect_anyway));
+        si.append("\n\n");
+        si.append(master.getString(R.string.mtm_cert_details));
+        certDetails(si, cert);
+        return si.toString();
+    }
+    /**
+     * Returns the top-most entry of the activity stack.
+     *
+     * @return the Context of the currently bound UI or the master context if none is bound
+     */
+    Context getUI() {
+        return (foregroundAct != null) ? foregroundAct : master;
+    }
+
+    int interact(final String message, final int titleId) {
+		/* prepare the MTMDecision blocker object */
+        MTMDecision choice = new MTMDecision();
+        final int myId = createDecisionId(choice);
+
+        masterHandler.post(new Runnable() {
+            public void run() {
+                Intent ni = new Intent(master, MemorizingActivity.class);
+                ni.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
+                ni.setData(Uri.parse(MemorizingTrustManager.class.getName() + "/" + myId));
+                ni.putExtra(DECISION_INTENT_ID, myId);
+                ni.putExtra(DECISION_INTENT_CERT, message);
+                ni.putExtra(DECISION_TITLE_ID, titleId);
+
+                // we try to directly start the activity and fall back to
+                // making a notification
+                try {
+                    getUI().startActivity(ni);
+                } catch (Exception e) {
+                    LOGGER.log(Level.FINE, "startActivity(MemorizingActivity)", e);
+                }
+            }
+        });
+
+        LOGGER.log(Level.FINE, "openDecisions: " + openDecisions + ", waiting on " + myId);
+        try {
+            synchronized(choice) { choice.wait(); }
+        } catch (InterruptedException e) {
+            LOGGER.log(Level.FINER, "InterruptedException", e);
+        }
+        LOGGER.log(Level.FINE, "finished wait on " + myId + ": " + choice.state);
+        return choice.state;
+    }
+
+    void interactCert(final X509Certificate[] chain, String authType, CertificateException cause)
+            throws CertificateException
+    {
+        switch (interact(certChainMessage(chain, cause), R.string.mtm_accept_cert)) {
+            case MTMDecision.DECISION_ALWAYS:
+                storeCert(chain[0]); // only store the server cert, not the whole chain
+            case MTMDecision.DECISION_ONCE:
+                break;
+            default:
+                throw (cause);
+        }
+    }
+
+    boolean interactHostname(X509Certificate cert, String hostname)
+    {
+        switch (interact(hostNameMessage(cert, hostname), R.string.mtm_accept_servername)) {
+            case MTMDecision.DECISION_ALWAYS:
+                storeCert(hostname, cert);
+            case MTMDecision.DECISION_ONCE:
+                return true;
+            default:
+                return false;
+        }
+    }
+
+    public static void interactResult(int decisionId, int choice) {
+        MTMDecision d;
+        synchronized(openDecisions) {
+            d = openDecisions.get(decisionId);
+            openDecisions.remove(decisionId);
+        }
+        if (d == null) {
+            LOGGER.log(Level.SEVERE, "interactResult: aborting due to stale decision reference!");
+            return;
+        }
+        synchronized(d) {
+            d.state = choice;
+            d.notify();
+        }
+    }
+
+    class MemorizingHostnameVerifier implements DomainHostnameVerifier {
+        private final HostnameVerifier defaultVerifier;
+        private final boolean interactive;
+
+        public MemorizingHostnameVerifier(HostnameVerifier wrapped, boolean interactive) {
+            this.defaultVerifier = wrapped;
+            this.interactive = interactive;
+        }
+
+        @Override
+        public boolean verify(String domain, String hostname, SSLSession session) {
+            LOGGER.log(Level.FINE, "hostname verifier for " + domain + ", trying default verifier first");
+            // if the default verifier accepts the hostname, we are done
+            if (defaultVerifier instanceof DomainHostnameVerifier) {
+                if (((DomainHostnameVerifier) defaultVerifier).verify(domain,hostname, session)) {
+                    return true;
+                }
+            } else {
+                if (defaultVerifier.verify(domain, session)) {
+                    return true;
+                }
+            }
+
+
+            // otherwise, we check if the hostname is an alias for this cert in our keystore
+            try {
+                X509Certificate cert = (X509Certificate)session.getPeerCertificates()[0];
+                //Log.d(TAG, "cert: " + cert);
+                if (cert.equals(appKeyStore.getCertificate(domain.toLowerCase(Locale.US)))) {
+                    LOGGER.log(Level.FINE, "certificate for " + domain + " is in our keystore. accepting.");
+                    return true;
+                } else {
+                    LOGGER.log(Level.FINE, "server " + domain + " provided wrong certificate, asking user.");
+                    if (interactive) {
+                        return interactHostname(cert, domain);
+                    } else {
+                        return false;
+                    }
+                }
+            } catch (Exception e) {
+                e.printStackTrace();
+                return false;
+            }
+        }
+
+        @Override
+        public boolean verify(String domain, SSLSession sslSession) {
+            return verify(domain,null,sslSession);
+        }
+    }
+
+
+    public X509TrustManager getNonInteractive(String domain) {
+        return new NonInteractiveMemorizingTrustManager(domain);
+    }
+
+    public X509TrustManager getInteractive(String domain) {
+        return new InteractiveMemorizingTrustManager(domain);
+    }
+
+    public X509TrustManager getNonInteractive() {
+        return new NonInteractiveMemorizingTrustManager(null);
+    }
+
+    public X509TrustManager getInteractive() {
+        return new InteractiveMemorizingTrustManager(null);
+    }
+
+    private class NonInteractiveMemorizingTrustManager implements X509TrustManager {
+
+        private final String domain;
+
+        public NonInteractiveMemorizingTrustManager(String domain) {
+            this.domain = domain;
+        }
+
+        @Override
+        public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException {
+            MemorizingTrustManager.this.checkCertTrusted(chain, authType, domain, false, false);
+        }
+
+        @Override
+        public void checkServerTrusted(X509Certificate[] chain, String authType)
+                throws CertificateException {
+            MemorizingTrustManager.this.checkCertTrusted(chain, authType, domain, true, false);
+        }
+
+        @Override
+        public X509Certificate[] getAcceptedIssuers() {
+            return MemorizingTrustManager.this.getAcceptedIssuers();
+        }
+
+    }
+
+    private class InteractiveMemorizingTrustManager implements X509TrustManager {
+        private final String domain;
+
+        public InteractiveMemorizingTrustManager(String domain) {
+            this.domain = domain;
+        }
+
+        @Override
+        public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException {
+            MemorizingTrustManager.this.checkCertTrusted(chain, authType, domain, false, true);
+        }
+
+        @Override
+        public void checkServerTrusted(X509Certificate[] chain, String authType)
+                throws CertificateException {
+            MemorizingTrustManager.this.checkCertTrusted(chain, authType, domain, true, true);
+        }
+
+        @Override
+        public X509Certificate[] getAcceptedIssuers() {
+            return MemorizingTrustManager.this.getAcceptedIssuers();
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/de/pixart/messenger/services/XmppConnectionService.java b/src/main/java/de/pixart/messenger/services/XmppConnectionService.java
index d26114b47..2c2f0b2d4 100644
--- a/src/main/java/de/pixart/messenger/services/XmppConnectionService.java
+++ b/src/main/java/de/pixart/messenger/services/XmppConnectionService.java
@@ -70,7 +70,6 @@ import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicLong;
 
-import de.duenndns.ssl.MemorizingTrustManager;
 import de.pixart.messenger.BuildConfig;
 import de.pixart.messenger.Config;
 import de.pixart.messenger.R;
diff --git a/src/main/java/de/pixart/messenger/ui/MemorizingActivity.java b/src/main/java/de/pixart/messenger/ui/MemorizingActivity.java
new file mode 100644
index 000000000..8172e6f9c
--- /dev/null
+++ b/src/main/java/de/pixart/messenger/ui/MemorizingActivity.java
@@ -0,0 +1,119 @@
+/* MemorizingTrustManager - a TrustManager which asks the user about invalid
+ *  certificates and memorizes their decision.
+ *
+ * Copyright (c) 2010 Georg Lukas <georg@op-co.de>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package de.pixart.messenger.ui;
+
+import android.content.DialogInterface;
+import android.content.DialogInterface.OnCancelListener;
+import android.content.DialogInterface.OnClickListener;
+import android.content.Intent;
+import android.content.SharedPreferences;
+import android.os.Bundle;
+import android.preference.PreferenceManager;
+import android.support.v7.app.AlertDialog;
+import android.support.v7.app.AppCompatActivity;
+
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+import de.pixart.messenger.R;
+import de.pixart.messenger.entities.MTMDecision;
+import de.pixart.messenger.services.MemorizingTrustManager;
+
+public class MemorizingActivity extends AppCompatActivity implements OnClickListener,OnCancelListener {
+
+    private final static Logger LOGGER = Logger.getLogger(MemorizingActivity.class.getName());
+
+    int decisionId;
+
+    AlertDialog dialog;
+
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        LOGGER.log(Level.FINE, "onCreate");
+        //setTheme(findTheme());
+        super.onCreate(savedInstanceState);
+    }
+
+    @Override
+    public void onResume() {
+        super.onResume();
+        Intent i = getIntent();
+        decisionId = i.getIntExtra(MemorizingTrustManager.DECISION_INTENT_ID, MTMDecision.DECISION_INVALID);
+        int titleId = i.getIntExtra(MemorizingTrustManager.DECISION_TITLE_ID, R.string.mtm_accept_cert);
+        String cert = i.getStringExtra(MemorizingTrustManager.DECISION_INTENT_CERT);
+        LOGGER.log(Level.FINE, "onResume with " + i.getExtras() + " decId=" + decisionId + " data: " + i.getData());
+        dialog = new AlertDialog.Builder(this).setTitle(titleId)
+                .setMessage(cert)
+                .setPositiveButton(R.string.always, this)
+                .setNeutralButton(R.string.once, this)
+                .setNegativeButton(R.string.cancel, this)
+                .setOnCancelListener(this)
+                .create();
+        dialog.show();
+    }
+
+    @Override
+    protected void onPause() {
+        if (dialog.isShowing())
+            dialog.dismiss();
+        super.onPause();
+    }
+
+    void sendDecision(int decision) {
+        LOGGER.log(Level.FINE, "Sending decision: " + decision);
+        MemorizingTrustManager.interactResult(decisionId, decision);
+        finish();
+    }
+
+    protected int findTheme() {
+        return 0;
+        //return getPreferences().getString(SettingsActivity.THEME, getResources().getString(R.string.theme)).equals("dark") ? R.style.ConversationsTheme_Dark : R.style.ConversationsTheme;
+    }
+
+    protected SharedPreferences getPreferences() {
+        return PreferenceManager
+                .getDefaultSharedPreferences(getApplicationContext());
+    }
+
+    // react on AlertDialog button press
+    public void onClick(DialogInterface dialog, int btnId) {
+        int decision;
+        dialog.dismiss();
+        switch (btnId) {
+            case DialogInterface.BUTTON_POSITIVE:
+                decision = MTMDecision.DECISION_ALWAYS;
+                break;
+            case DialogInterface.BUTTON_NEUTRAL:
+                decision = MTMDecision.DECISION_ONCE;
+                break;
+            default:
+                decision = MTMDecision.DECISION_ABORT;
+        }
+        sendDecision(decision);
+    }
+
+    public void onCancel(DialogInterface dialog) {
+        sendDecision(MTMDecision.DECISION_ABORT);
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/de/pixart/messenger/ui/SettingsActivity.java b/src/main/java/de/pixart/messenger/ui/SettingsActivity.java
index b8dac78c0..1b744314e 100644
--- a/src/main/java/de/pixart/messenger/ui/SettingsActivity.java
+++ b/src/main/java/de/pixart/messenger/ui/SettingsActivity.java
@@ -29,7 +29,7 @@ import java.util.Collections;
 import java.util.List;
 import java.util.Locale;
 
-import de.duenndns.ssl.MemorizingTrustManager;
+import de.pixart.messenger.services.MemorizingTrustManager;
 import de.pixart.messenger.Config;
 import de.pixart.messenger.R;
 import de.pixart.messenger.entities.Account;
diff --git a/src/main/java/de/pixart/messenger/xmpp/XmppConnection.java b/src/main/java/de/pixart/messenger/xmpp/XmppConnection.java
index 6bd4904bf..1025c5f1d 100644
--- a/src/main/java/de/pixart/messenger/xmpp/XmppConnection.java
+++ b/src/main/java/de/pixart/messenger/xmpp/XmppConnection.java
@@ -50,8 +50,8 @@ import javax.net.ssl.SSLSocketFactory;
 import javax.net.ssl.X509KeyManager;
 import javax.net.ssl.X509TrustManager;
 
-import de.duenndns.ssl.DomainHostnameVerifier;
-import de.duenndns.ssl.MemorizingTrustManager;
+import de.pixart.messenger.crypto.DomainHostnameVerifier;
+import de.pixart.messenger.services.MemorizingTrustManager;
 import de.pixart.messenger.Config;
 import de.pixart.messenger.crypto.XmppDomainVerifier;
 import de.pixart.messenger.crypto.axolotl.AxolotlService;