diff --git a/nodejs/public/javascripts/safechat.js b/nodejs/public/javascripts/safechat.js
index b16abd3..f8586dc 100644
--- a/nodejs/public/javascripts/safechat.js
+++ b/nodejs/public/javascripts/safechat.js
@@ -37,870 +37,1026 @@
 //       1         2         3         4         5         6         7         8
 // 45678901234567890123456789012345678901234567890123456789012345678901234567890
 
-function SafeChatClient(success, notice, error) {
+function SafeChat() {
 
-  /// Cache Client's Key from local Strorage
-  var k = null;
-
-  function browserSupported() {
-    window.indexedDB = window.indexedDB || window.mozIndexedDB || window.webkitIndexedDB || window.msIndexedDB
-    window.IDBTransaction = window.IDBTransaction || window.webkitIDBTransaction || window.msIDBTransaction
-    window.IDBKeyRange = window.IDBKeyRange || window.webkitIDBKeyRange || window.msIDBKeyRange
-    return window.indexedDB && window.crypto.getRandomValues && Storage
+  /// Create UID from a name by appending an E-Mail
+  function uid(name) {
+    return name+' <'+name+'@'+hostname+'>'
   }
 
-  /// Get User Key
-  /** @internal key ist cached in k
-      @return key */
-  function key() {
-    if (k) return k
-    if (typeof localStorage.key == 'undefined') return null
-    return k = openpgp.key.readArmored(localStorage.key)
-  }
+  /// @class Crypto cryptographic functions
+  /** @param view is of class SafeChat.View */
+  function Crypto(view) {
+
+    /// cache client's key from local strorage
+    var k = null
+
+    /// detect hosstname, default to safechat.ch
+    var hostname = window.location.hostname!='localhost'?window.location.hostname:'safechat.ch'
+    
+    /// get user key
+    /** @internal key ist cached in k
+       @return key */
+    function key() {
+      if (k) return k
+      if (typeof localStorage.key == 'undefined') return null
+      return k = openpgp.key.readArmored(localStorage.key)
+    }
+
+    /// get own user name
+    /** get user name as user id of first public key */
+    function user() {
+      if (k || key()) return k.pub.keys[0].getUserIds()[0]
+      return null
+    }
+
+    /// create New User
+    function createuser(user, email, pwd) {
+      view.notice("generating keys")
+      openpgp.generateKey({
+        numBits: 4096,
+        userIds: [{name: user, email: email}],
+        passphrase: pwd
+      }).then(function(keyPair) {
+        view.success("keys generated")
+        localStorage.key = keyPair.privateKeyArmored
+        k = keyPair.key
+      }).catch(function(e) {
+        console.log(e)
+        view.fatal("generating key pairs failed")
+      })
+    }
+
+    /// open private key with password
+    /** @return @c true if password matches */
+    function password(pwd) {
+      return (k || keys()) && k.keys[0].decrypt(pwd)
+    }
+
+    /// Encrypt Message
+    function encrypt(message, targetkeys, done, failed) {
+      if (!k) return false
+      openpgp.encrypt({
+        publicKeys: targetkeys.keys.concat(k.keys),
+        privateKeys: k,
+        data: message,
+        armor: false
+      }).then(done).else(failed)
+      return true
+    }
+
+    /// Decrypt Message
+    function decrypt(message, sourcekeys, done, failed) {
+      if (!k) return false
+      openpgp.decrypt({
+        privateKeys: k.keys,
+        publicKeys: sourcekeys.keys,
+        message: message
+      }).then(done).else(failed)
+      return true
+    }
 
-  /// Get Own User Name
-  /** Get user name as user id of first public key */
-  function uid() {
-    if (k || key()) return k.pub.keys[0].getUserIds()[0]
-    return null
   }
 
-  /// Create New User
-  function createuser(user, email, pwd) {
-    notice("generating keys")
-    openpgp.generateKey({
-      numBits: 4096,
-      userIds: [{name: user, email: email}],
-      passphrase: pwd
-    }).then(function(keyPair) {
-      success("keys generated")
-      localStorage.key = keyPair.privateKeyArmored
-      k = keyPair.key
-    }).catch(function(e) {
-      console.log(e)
-      error("generating key pairs failed")
-    })
+  /// database that stores in indexed db
+  function DataBase() {
+
+    function user(name, key) {
+    }
+    
   }
 
-  function password(pwd) {
-    return (k || keys()) && k.keys[0].decrypt(pwd)
+  /// manage local copy of users
+  function Users() {
+    
+    var users = new Map()
+    
+    function add(usr) {
+      if (!users[usr.name])
+        users[usr.name].valid = true
+      else
+        users[usr.name].valid = users[usr.name].valid && users[usr.name].key == usr.key
+      users[usr.name].key = usr.key
+      users[usr.name].online = usr.online
+    }
+    
   }
 
-  /// Encrypt Message
-  function encrypt(targetkeys, message, done, failed) {
-    if (!k) return false
-    openpgp.encrypt({
-      publicKeys: targets.keys.concat(k.keys),
-      privateKeys: k,
-      data: message,
-      armor: false})
-           .then(done)
-           .else(failed)
-    return true
+  /// manage local copy of messages
+  function Messages() {
+    
+    var messages = {};
+
+    function add() {
+    }
+    
   }
 
-  /// Decrypt Message
-  function decrypt(message) {
-    if (!k) return false
+  /// @class Communication client socket communication
+  /** @param view is of class SafeChat.View */
+  function Communication(controller) {
+    
+    var socket = io.connect()
+    
+    function broadcast(signal, data) {
+      console.log("<=snd "+signal)
+      socket.broadcast.emit(signal, data)
+    }
+
+    function emit(signal, data) {
+      console.log("<-snd "+signal)
+      socket.emit(signal, data)
+    }
+
+    socket
+      .on("login", controller.loggedin)
+      .on("fail", controller.fail)
+      .on("user", controller.user)
+      .on("users", controller.users)
+      .on("message", controller.message)
+      .on("messages", controller.messages)
+      .io
+      .on("connect", controller.connected)
+      .on("reconnect", controller.connected)
+      .on("disconnect", controller.disconnected)
+      .on("error", controller.disconnected)
     
-    return true
   }
-}
 
-var password = null; ///< password, only stored temporary, until reload
-var username = null; ///< username, only used during registration
-var filecontent = new Array(); ///< temporary storage for attachments
-var socket = io.connect();
-var hostname = window.location.hostname!='localhost'?window.location.hostname:'safechat.ch';
+  /// @class View provides the glue to the GUI in the index.ejs file
+  /** View provides the following callbacks:
+     - status updates:
+     - @c notice(msg) to display information 
+     - @c warning(msg) 
+     - @c error(msg)
+     - @c fatal(msg) */
+  function View() {
 
-/// Padding for numbers in dates
-function pad(n) {
-  return n<10 ? '0'+n : n
-}
+    var nexttimer = null
 
-function uid(name) {
-  return name+' <'+name+'@'+hostname+'>';
-}
+    /// Padding for numbers in dates
+    function pad(n) {
+      return n<10 ? '0'+n : n
+    }
+
+    /// escape text to show in html @see htmldec
+    function htmlenc(html) {
+      return $('<div/>').text(html).html()
+    }
+
+    /// decode html encoded text @see htmlenc
+    function htmldec(data) {
+      return $('<div/>').html(data).text()
+    }
 
-/// Convert number of bytes to readable text
-function size(num) {
-  if (num>0.6*1024) {
-    if (num>0.6*1024*1024) {
-      if (num>0.6*1024*1024*1024) {
-        if (num>0.6*1024*1024*1024*1024) {
-          return Math.round(num/1024/1024/1024/1024)+"TB";
+    /// alert user accoustically or by vibration
+    /** alert user, e.g. that a new message has arrived. */
+    function beep() {
+      if (navigator.vibrate) navigator.vibrate(1000)
+      (new Audio("sounds/beep.mp3")).play()
+    }
+
+    /// show fatal error
+    /** something completely failed, abort
+        @param msg  */
+    function fatal(msg) {
+      if (nexttimer) clearTimeout(nexttimer)
+      if (msg) {
+        error(msg)
+        $('#fatal-msg').html(msg)
+      }
+      show('fatal')
+    }
+    
+    /// show error messsage
+    /** shows an error message and logs to console.
+        @param data (optional) The error can be a string or any structure.
+               Strings are shown to the user, structures are logged only.
+        @param next (optional) next function to call */
+    function error(data, next) {
+      if (nexttimer) clearTimeout(nexttimer)
+      $("#status").hide()
+      $("#status").addClass("error")
+      $("#status").removeClass("notice")
+      $("#status").removeClass("success")
+      if (data) {
+        if (typeof data == 'string') {
+          $("#status").html(data)
+          console.log("error: "+data)
         } else {
-          return Math.round(num/1024/1024/1024)+"GB";
+          $("#status").html('error')
+          console.log("error: "+JSON.stringify(data))
         }
       } else {
-        return Math.round(num/1024/1024)+"MB";
+        $("#status").html('error')
+        console.log("error")
       }
-    } else {
-      return Math.round(num/1024)+"kB";
+      $("#status").show()
+      if (next) nexttimer = setTimeout(function() {
+        nexttimer = null
+        next()
+      }, 5000)
     }
-  } else {
-    return num+"B";
-  }
-}
 
-var reboottimer = null;
-/// Show error messsage
-/** Fades in an error message and logs to console.
-   @param data (optional) The error can be a string or any structure.
-   Strings are shown to the user, structures are logged only.
-   @param stay (optional) If not given as @c true, reloads page after 5s. */
-function error(data, stay) {
-  $("#status").hide();
-  $("#status").addClass("error")
-  $("#status").removeClass("notice")
-  $("#status").removeClass("success")
-  if (data) {
-    if (typeof data == 'string') {
-      $("#status").html(data);
-      console.log("error: "+data);
-    } else {
-      $("#status").html('unknown error: '+JSON.stringify(data));
-      console.log("error: "+JSON.stringify(data));
+    /// show notice messsage
+    /** shows an notice message and logs to console.
+        @param text (optional) The data is a string. */
+    function notice(text) {
+      $("#status").hide()
+      $("#status").addClass("notice")
+      $("#status").removeClass("error")
+      $("#status").removeClass("success")
+      if (text) {
+        $("#status").html(text)
+        console.log("notice: "+text)
+      } else {
+        $("#status").html('')
+        console.log("notice")
+      }
+      $("#status").show()
     }
-  } else {
-    $("#status").html('error');
-    console.log("error");
-  }
-  $("#status").show();
-  if (!stay) {
-    console.log("reboot in 5s");
-    console.log((new Error('stacktrace')).stack);
-    if (!reboottimer) reboottimer = setTimeout(function() {
-      reboottimer = null;
-      start();
-    }, 5000);
-  }
-}
 
-/// Show notice messsage
-/** Fades in an notice message and logs to console.
-   @param text (optional) The data is a string. */
-function notice(text) {
-  $("#status").hide()
-  $("#status").addClass("notice")
-  $("#status").removeClass("error")
-  $("#status").removeClass("success")
-  if (text) {
-    $("#status").html(text);
-    console.log("notice: "+text);
-  } else {
-    $("#status").html('');
-    console.log("notice");
-  }
-  $("#status").show();
-}
+    /// show success messsage
+    /** shows an success message and logs to console.
+        @param text (optional) The data is a string. */
+    function success(text) {
+      $("#status").hide()
+      $("#status").addClass("success")
+      $("#status").removeClass("error")
+      $("#status").removeClass("notice")
+      if (text) {
+        $("#status").html(text)
+        console.log("success: "+text)
+      } else {
+        $("#status").html('')
+        console.log("success")
+      }
+      $("#status").show()
+    }
 
-/// Show notice messsage
-/** Fades in an success message and logs to console.
-   @param text (optional) The data is a string. */
-function success(text) {
-  $("#status").hide();
-  $("#status").addClass("success")
-  $("#status").removeClass("error")
-  $("#status").removeClass("notice")
-  if (text) {
-    $("#status").html(text);
-    console.log("success: "+text);
-  } else {
-    $("#status").html('');
-    console.log("success");
-  }
-  $("#status").show();
-}
+    /// show a specific screen given the element id
+    /** @param id html id to be shown.
+        @param msg (optional) the success message text */
+    function show(id, msg) {
+      console.log("state: "+id)
+      if (msg) success(msg) else $("#status").hide()
+      $("#main").children(":not(#"+id+")").hide()
+      $("#main #"+id).show()
+      $("#main #"+id+" form input:first-child").focus()
+    }
 
-/// Show status message in the main screen area
-/** @param id HTML id to be shown.
-   @param msg The success message text */
-function status(id, msg) {
-  console.log("state: "+id);
-  if (msg) success(msg); else $("#status").hide();
-  $("#main").children(":not(#"+id+")").hide();
-  $("#main #"+id).show();
-  $("#main #"+id+" form input:first-child").focus();
-}
+    /// show server connected status
+    function connected() {
+      console.log("server connected")
+      $("#connectionstatus #bad").hide()
+      $("#connectionstatus #good").show()
+      success("server connected")
+    }
 
-function emit(signal, data) {
-  console.log("<-snd "+signal);
-  socket.emit(signal, data);
-}
+    /// show server disconnected status
+    function disconnected() {
+      console.log("server disconnected")
+      $("#connectionstatus #good").hide()
+      $("#connectionstatus #bad").show()
+      error("server disconnected", true)
+    }
+    
+    /// toggle menu display
+    function togglemenu() {
+      $("#menu").toggle()
+    }
 
-function connected() {
-  console.log("server connected");
-  $("#connectionstatus #bad").hide();
-  $("#connectionstatus #good").show();
-  success("server connected");
-}
+    function checkFeature(id, query) {
+      if (query) $('#'+id+':before')
+        .css('color', 'green')
+        .css('content', '&#x2714;')
+      else $('#'+id+':before')
+        .css('color', 'red')
+        .css('content', '&#x2718;')
+      if (query) $('#'+id)
+        .css('color', 'green')
+        .css('text-decoration', 'line-through')
+      else $('#'+id)
+        .css('color', 'red')
+        .css('text-decoration', 'none')
+    }
 
-function disconnected() {
-  console.log("server disconnected");
-  $("#connectionstatus #good").hide();
-  $("#connectionstatus #bad").show();
-  error("server disconnected", true);
-}
+    function checkFeatures() {
+      $('ul.features').css('list-style-type', 'none')
+      checkFeature("localstorage", Storage)
+      checkFeature("indexeddb", window.indexedDB)
+      checkFeature("randomvalues", window.crypto.getRandomValues)
+      checkFeature("vibrate", navigator.vibrate)
+      checkFeature("filereader", window.FileReader)
+    }
 
-function connectionstatus() {
-  if (socket.connected) connected(); else disconnected();
-}
+    function DataTransfer() {
+      
+      var reboottimer = null
+      var data = new DataTransfer()
+
+      /// download profile backup
+      function backup() {
+        var download = document.createElement('a')
+        download.href = 'data:attachment/text,'+encodeURI(JSON.stringify(localStorage))
+        download.target = '_blank'
+        var now = new Date()
+        download.download =
+        pad(now.getFullYear())+pad(now.getMonth()+1)+pad(now.getDate())+
+        "-"+userid()+"@"+hostname+".bak"
+        var clickEvent = new MouseEvent("click", {
+          "view": window,
+          "bubbles": true,
+          "cancelable": false
+        })
+        download.dispatchEvent(clickEvent)
+        togglemenu()
+      }
+      
+      /// Upload Profile Backup
+      function restore(evt) {
+        for (var i=0, f; f=evt.target.files[i]; ++i) {
+          var file = f
+          var reader = new FileReader()
+          reader.onload = function(evt) {
+            if (evt.target.error) return error("error reading file")
+            if (evt.target.readyState==0) return notice("waiting for data …")
+            if (evt.target.readyState==1) return notice("loading data …")
+            var parsed=JSON.parse(evt.target.result)
+            togglemenu()
+            localStorage.pubkey = parsed.pubkey
+            localStorage.privkey = parsed.privkey
+            success("backup is restored")
+            console.log("reboot after restore in 2s")
+            if (!reboottimer && reboot) reboottimer = setTimeout(function() {
+              reboottimer = null
+            }, 2000)
+          }
+          reader.readAsText(file)
+        }
+      }
 
-function htmlenc(html) {
-  return $('<div/>').text(html).html();
-}
+      if (!window.FileReader) {
+        $('restore-menu-item').hide()
+        error("your browser does not support file upload")
+      }
 
-function htmldec(data) {
-  return $('<div/>').html(data).text();
-}
+    }
 
-/// Alert user
-/** Alert user, e.g. that a new message has arrived. */
-function beep(user) {
-  if (user) success("message from "+htmlenc(user)+" received");
-  navigator.vibrate =
-  navigator.vibrate || navigator.webkitVibrate || navigator.mozVibrate || navigator.msVibrate;
-  if (navigator.vibrate) {
-    // vibration API supported
-    navigator.vibrate(1000);
   }
-  (new Audio("sounds/A-Tone-His_Self-1266414414.mp3")).play();
-}
 
-/// Toggle Menu Display
-function togglemenu() {
-  $("#menu").toggle();
-}
+  /// @class Controller defines the programm flow
+  function Controller(view) {
+    
+    var db = new Database()
+    var communication = new Communication(this)
+    var users = new Users()
+    
+    function fail(msg) {
+      console.log('rcv-> fail('+msg+')')
+      error(msg)
+    }
 
-/// Download Profile Backup
-function backup() {
-  var download = document.createElement('a');
-  download.href = 'data:attachment/text,'+encodeURI(JSON.stringify(localStorage));
-  download.target = '_blank';
-  var now = new Date();
-  download.download =
-  pad(now.getFullYear())+pad(now.getMonth()+1)+pad(now.getDate())+
-  "-"+userid()+"@"+hostname+".bak";
-  var clickEvent = new MouseEvent("click", {
-    "view": window,
-    "bubbles": true,
-    "cancelable": false
-  });
-  download.dispatchEvent(clickEvent);
-  togglemenu();
-}
+    function loggedin() {
+      console.log("rcv-> login")
+      success("login successful")
+      chat()
+    }
+    
+    function user(usr) {
+      console.log("rcv-> user")
+      if (usr.exits) users.add(usr)
+    }
 
-/// Upload Profile Backup
-function restore(evt) {
-  if (!window.FileReader)
-    return error("your browser does not support file upload", true);
-  for (var i=0, f; f=evt.target.files[i]; ++i) {
-    var file = f;
-    var reader = new FileReader();
-    reader.onload = function(evt) {
-      if (evt.target.error) return error("error reading file", true);
-      if (evt.target.readyState==0) return notice("waiting for data …");
-      if (evt.target.readyState==1) return notice("loading data …");
-      var parsed=JSON.parse(evt.target.result);
-      togglemenu();
-      localStorage.pubkey = parsed.pubkey;
-      localStorage.privkey = parsed.privkey;
-      success("backup is restored");
-      console.log("reboot after restore in 2s");
-      if (!reboottimer) reboottimer = setTimeout(function() {
-        reboottimer = null;
-        start();
-      }, 2000);
-    }
-    reader.readAsText(file);
-  }
-}
+    function users() {
+      console.log("rcv-> users")
+    }
+    
+    function message(msg) {
+      console.log("rcv-> message")
+    }
+    
+    function messages(msgs) {
+      console.log("rcv-> messages")
+    }
 
-/// Configure local groups
-/** … */
-function groups() {
-}
+    this.connected = view.connected
+    this.reconnect = view.connected
+    this.disconnect = view.disconnected
+    this.error = view.disconnected
 
-/// Check if password is set and matches the repeated password
-/** Checks if both passwords are identical and valid and gives
-   feedback to the user.
-
-   Called when user edits the password fields.
-
-   Sets @ref username and checks @ref password - if both are well
-   defined, enables the submit button.
-
-   @param pwd The password.
-   @param pwd2 The repeated password. */
-function checkpwd(pwd, pwd2) {
-  $("#register").submit(function(event) {
-    return false;
-  });
-  if (pwd==pwd2) password=pwd;
-  else password=null;
-  if (!password||password.length<1) password=null;
-  $("#createuser").prop("disabled", !(username && password));
-  if (password) {
-    if (username) success("user is ready to be created");
-    else notice("password matches, please chose a valid user name");
-  } else {
-    if (username) notice("passwords don't match");
-    else if ($('#user').val()) notice("user name is already in use");
-    else notice("please chose a user name");
-    
-  }
-}
+    function login() {
+    }
 
-/// Checks if the receiver of a message exists on server.
-/** Calls checknewuser.php on server and enables the message submit
-   button if the receiver of the message exists on the server. */
-function checkpartner(user) {
-  $("#chat").submit(function(event) {
-    return false;
-  });
-  emit("user", uid(user));
-}
+    function user(usr) {
+      if (usr.exists) db.adduser
+    }
 
-/// Create Local Public-/Private-Key Pair
-/** Called if user has not yet his keys, just generates a new key pair. */
-function createkeypair(user, pwd) {
-  notice("generating keys");
-  openpgp.generateKey({
-    numBits: 4096,
-    userIds: [{name: user, email: user+'@'+hostname}],
-    passphrase: pwd
-  }).then(function(keyPair) {
-    success("keys generated");
-    localStorage.pubkey = keyPair.publicKeyArmored;
-    localStorage.privkey = keyPair.privateKeyArmored;
-    login();
-  }).catch(function(e) {
-    console.log(e)
-    error("generating key pairs failed")
-  });
-}
+    function initBrowser() {
+      window.indexedDB = window.indexedDB || window.mozIndexedDB || window.webkitIndexedDB || window.msIndexedDB
+      window.IDBTransaction = window.IDBTransaction || window.webkitIDBTransaction || window.msIDBTransaction
+      window.IDBKeyRange = window.IDBKeyRange || window.webkitIDBKeyRange || window.msIDBKeyRange
+      navigator.vibrate = navigator.vibrate || navigator.webkitVibrate || navigator.mozVibrate || navigator.msVibrate
+      return window.indexedDB && window.crypto.getRandomValues && Storage
+    }
 
-/// Get Own Public Key
-/** @return public key object */
-function publicKey() {
-  if (typeof localStorage.pubkey == 'undefined') {
-    if (typeof localStorage.pubKey == 'undefined') {
-      return null;
-    } else {
-      localStorage.pubkey = localStorage.pubKey;
-      localStorage.removeItem(pubKey);
+    function run() {
     }
-  }
-  return openpgp.key.readArmored(localStorage.pubkey);
-}
 
-/// Get Own Private Key
-/** @return private key object */
-function privateKey() {
-  if (typeof localStorage.privkey == 'undefined') {
-    if (typeof localStorage.privKey == 'undefined') {
-      return null;
-    } else {
-      localStorage.privkey = localStorage.privKey;
-      localStorage.removeItem(privKey);
+    function start() {
+      view.reboot = run
+      var compatible = initBrowser()
+      view.checkFeatures()
+      if (!compatible)
+        view.fatal("your browser is not supported")
+      else
+        run()
     }
+
   }
-  return openpgp.key.readArmored(localStorage.privkey);
-}
 
-/// Get Own User Name
-/** Get user name as user id of first public key */
-function userid() {
-  if (!publicKey() ||
-      publicKey().keys.length < 1 ||
-      publicKey().keys[0].getUserIds().length < 1) return null
-  return publicKey().keys[0].getUserIds()[0];
-}
+  //==============================================================================
 
-/// Clear Message Text And Attachments
-/** Does not remove the receiver's name */
-function clearmessage() {
-  $("#message").prop(":disabled", true);
-  filecontent = new Array();
-  $('#preview').empty();
-  $("#msg").val("");
-  $("#message").prop(":disabled", false);
-}
+  //------------------------------------------------------------------------------
+  return new Controller(new View())
 
-function guessfilename(mimetype, user, date) {
-  if (!user) user = userid();
-  if (!date) date = new Date();
-  var ext = mimetype.replace(/.*\/(x-)?/i, "");
-  return pad(date.getFullYear())+pad(date.getMonth()+1)+pad(date.getDate())
-        +"-"+ext+"-"+user+"@"+hostname+'.'+ext;
 }
+  
+  var filecontent = new Array() ///< temporary storage for attachments
+  var reboottimer = null
 
-/// Display Image Attachments
-function attachments(files, id, from, date) {
-  if (files) files.forEach(function(file) {
-    console.log(file);
-    if (!file.name) file.name = guessfilename(file.type, from, date);
-    var a = document.createElement('a');
-    a.href = file.content;
-    a.download = file.name;
-    a.target = '_blank';
-    if (file.type.match('^image/')) {
-      var img = document.createElement('img');
-      img.title = file.name;
-      img.src = file.content;
-      a.appendChild(img);
-    } else if (file.type.match('^video/')) {
-      var video = document.createElement('video');
-      video.controls = true;
-      video.title = file.name;
-      video.src = file.content;
-      a.appendChild(video);
-    } else {
-      var img = document.createElement('img');
-      img.title = file.name;
-      img.src = "images/Document_sans_PICOL-PIctorial-COmmunication-Language.svg";
-      a.appendChild(img);
-    }
-    $(id).append(a);            
-  });
-}
+  function connectionstatus() {
+    if (socket.connected) connected() else disconnected()
+  }
+
+  /// Configure local groups
+  /** … */
+  function groups() {
+  }
+
+  /// Check if password is set and matches the repeated password
+  /** Checks if both passwords are identical and valid and gives
+     feedback to the user.
 
-var recorder;
+     Called when user edits the password fields.
 
-function done() {
-  if (recorder) {
-    recorder.stop();
-    recorder.recording(function(data) {
-      previewfile(data, "video/webm");
-      abort();
-    });
+     Sets @ref username and checks @ref password - if both are well
+     defined, enables the submit button.
+
+     @param pwd The password.
+     @param pwd2 The repeated password. */
+  function checkpwd(pwd, pwd2) {
+    $("#register").submit(function(event) {
+      return false
+    })
+    if (pwd==pwd2) password=pwd
+    else password=null
+    if (!password||password.length<1) password=null
+    $("#createuser").prop("disabled", !(username && password))
+    if (password) {
+      if (username) success("user is ready to be created")
+      else notice("password matches, please chose a valid user name")
+    } else {
+      if (username) notice("passwords don't match")
+      else if ($('#user').val()) notice("user name is already in use")
+      else notice("please chose a user name")
+      
+    }
   }
-}
 
-function abort() {
-  if (recorder) {
-    $("#videorecorder").hide();
-    recorder.release();
-    delete recorder; recorder = null;
+  /// Checks if the receiver of a message exists on server.
+  /** Calls checknewuser.php on server and enables the message submit
+     button if the receiver of the message exists on the server. */
+  function checkpartner(user) {
+    $("#chat").submit(function(event) {
+      return false
+    })
+    emit("user", uid(user))
   }
-}
 
-/// Record Video from builtin camera
-function recordvideo() {
-  try {
-    abort();
-    $("#videorecorder").show();
-    recorder = new MediaStreamRecorder({
-      video: {
-        width: {ideal: 180},
-        height: {ideal: 160}
-      },
-      audio: true
-    });
-    recorder.on("ready", function() {
-      $("#videorecorder video").attr("src", recorder.preview());
-      $("#videorecorder video").css("width", 180);
-      $("#videorecorder video").css("height", 160);
-      $("#videorecorder video").attr("width", 180);
-      $("#videorecorder video").attr("height", 160);
-      recorder.start();
-    });
-  } catch (e) {
-    console.log(e);
-    error("cannot access camera", true);
+  /// Create Local Public-/Private-Key Pair
+  /** Called if user has not yet his keys, just generates a new key pair. */
+  function createkeypair(user, pwd) {
+    notice("generating keys")
+    openpgp.generateKey({
+      numBits: 4096,
+      userIds: [{name: user, email: user+'@'+hostname}],
+      passphrase: pwd
+    }).then(function(keyPair) {
+      success("keys generated")
+      localStorage.pubkey = keyPair.publicKeyArmored
+      localStorage.privkey = keyPair.privateKeyArmored
+      login()
+    }).catch(function(e) {
+      console.log(e)
+      error("generating key pairs failed")
+    })
   }
-}
 
-function previewfile(content, type, name) {
-  if (!name) name = guessfilename(type);
-  if (type.match('^image/')) {
-    var img = document.createElement("img");
-    img.onload = function() { // resize image to maximum 400px
-      var MAX = 400;
-      var width = img.width;
-      var height = img.height;
-      if (width > MAX) {
-        height *= MAX / width;
-        width = MAX;
-      }
-      if (height > MAX) {
-        width *= MAX / height;
-        height = MAX;
+  /// Get Own Public Key
+  /** @return public key object */
+  function publicKey() {
+    if (typeof localStorage.pubkey == 'undefined') {
+      if (typeof localStorage.pubKey == 'undefined') {
+        return null
+      } else {
+        localStorage.pubkey = localStorage.pubKey
+        localStorage.removeItem(pubKey)
       }
-      var canvas = document.createElement("canvas");
-      canvas.width = width;
-      canvas.height = height;
-      var ctx = canvas.getContext("2d");
-      ctx.drawImage(img, 0, 0, width, height);
-      img.onload = function() {
-        filecontent.push({name: name, type: type, content: img.src});
-        $("#preview").append(img);
-        success('image is ready to be sent');
+    }
+    return openpgp.key.readArmored(localStorage.pubkey)
+  }
+
+  /// Get Own Private Key
+  /** @return private key object */
+  function privateKey() {
+    if (typeof localStorage.privkey == 'undefined') {
+      if (typeof localStorage.privKey == 'undefined') {
+        return null
+      } else {
+        localStorage.privkey = localStorage.privKey
+        localStorage.removeItem(privKey)
       }
-      img.src = canvas.toDataURL(file.type);
-      img.title = name+"\n"+size(img.src.length);
-    }
-    img.src=content;
-  } else if (type.match('^video/')) {
-    filecontent.push({name: name, type: type, content: content});
-    var video = document.createElement("video");
-    video.setAttribute("controls", "controls");
-    video.setAttribute("loop", "loop");
-    video.setAttribute("src", content);
-    video.setAttribute("title", name+"\n"+size(content.length));
-    $("#preview").append(video);
-  } else {
-    filecontent.push({name: name, type: type, content: content});
-    var img = document.createElement("img");
-    img.src = "images/Document_sans_PICOL-PIctorial-COmmunication-Language.svg";
-    img.title = name+"\n"+size(content.length);
-    $("#preview").append(img);
+    }
+    return openpgp.key.readArmored(localStorage.privkey)
   }
-}
 
-/// Upload Attachment
-/** Prepares attachment to be sent in a message. If the attachment is
-   an image, it resizes the image to 400px on the lager side.
-
-   By now, only images are supported.
-
-   Stores data in global variable @ref filecontent. */
-function fileupload(evt) {
-  if (!window.FileReader)
-    return error("your browser does not support file upload", true);
-  for (var i=0, f; f=evt.target.files[i]; ++i) {
-    var file = f;
-    var reader = new FileReader();
-    reader.onload = function(evt) {
-      if (evt.target.error) return error("error reading file", true);
-      if (evt.target.readyState==0) return notice("waiting for data …");
-      if (evt.target.readyState==1) return notice("loading data …");
-      previewfile(evt.target.result, file.type, file.name);
-    }
-    reader.readAsDataURL(file);
+  /// Get Own User Name
+  /** Get user name as user id of first public key */
+  function userid() {
+    if (!publicKey() ||
+        publicKey().keys.length < 1 ||
+        publicKey().keys[0].getUserIds().length < 1) return null
+    return publicKey().keys[0].getUserIds()[0]
   }
-}
 
-/// Sets Receiver's Name
-/** Called when clicked on a receiver's name. Sets focus to the
-   message text field.
+  /// Clear Message Text And Attachments
+  /** Does not remove the receiver's name */
+  function clearmessage() {
+    $("#message").prop(":disabled", true)
+    filecontent = new Array()
+    $('#preview').empty()
+    $("#msg").val("")
+    $("#message").prop(":disabled", false)
+  }
 
-   @param name The receiver's name. */
-function setreceiver(name) {
-  $("#recv").val(name);
-  checkpartner(name);
-  $("#msg").focus();
-}
+  function guessfilename(mimetype, user, date) {
+    if (!user) user = userid()
+    if (!date) date = new Date()
+    var ext = mimetype.replace(/.*\/(x-)?/i, "")
+    return pad(date.getFullYear())+pad(date.getMonth()+1)+pad(date.getDate())
+          +"-"+ext+"-"+user+"@"+hostname+'.'+ext
+  }
 
-var userMap = null;
-function users(userlist) {
-  console.log("rcv-> users");
-  userMap = new Array();
-  $("#allusers").empty();
-  userlist.forEach(function(usr) {
-    userMap[usr.name] = usr.pubkey;
-    $("#allusers").append('<option value="'+htmlenc(usr.name)+'">')
-    $("#allusers").hide();
-    console.log("   user: "+usr.name);
-  });
-  localStorage.userMap = JSON.stringify(userMap);
-}
+  /// Display Image Attachments
+  function attachments(files, id, from, date) {
+    if (files) files.forEach(function(file) {
+      console.log(file)
+      if (!file.name) file.name = guessfilename(file.type, from, date)
+      var a = document.createElement('a')
+      a.href = file.content
+      a.download = file.name
+      a.target = '_blank'
+      if (file.type.match('^image/')) {
+        var img = document.createElement('img')
+        img.title = file.name
+        img.src = file.content
+        a.appendChild(img)
+      } else if (file.type.match('^video/')) {
+        var video = document.createElement('video')
+        video.controls = true
+        video.title = file.name
+        video.src = file.content
+        a.appendChild(video)
+      } else {
+        var img = document.createElement('img')
+        img.title = file.name
+        img.src = "images/Document_sans_PICOL-PIctorial-COmmunication-Language.svg"
+        a.appendChild(img)
+      }
+      $(id).append(a)            
+    })
+  }
 
-function fail(msg) {
-  console.log("rcv-> fail");
-  error(msg);
-}
+  var recorder
 
-function loggedin() {
-  console.log("rcv-> login");
-  success("login successful");
-  chat();
-}
+  function done() {
+    if (recorder) {
+      recorder.stop()
+      recorder.recording(function(data) {
+        previewfile(data, "video/webm")
+        abort()
+      })
+    }
+  }
 
-function user(usr) {
-  if (usr.exists) console.log("rcv-> user("+usr.name+")");
-  else console.log("rcv-> user("+usr.name+"): name is available");
-  if ($("#newuser").is(":visible") && usr.name==uid($('#user').val())) {
-    // same username as in the create user form
-    $("#createuser").prop("disabled", usr.exists); // todo: check password
-    if (!usr.exists) {
-      username = usr.name;
-      success("user name "+usr.name+" is available");
-    } else {
-      username = null;
-      error("user name "+usr.name+" is in use", true);
+  function abort() {
+    if (recorder) {
+      $("#videorecorder").hide()
+      recorder.release()
+      delete recorder recorder = null
     }
   }
-  if ($("#chat").is(":visible") && usr.name==uid($("#recv").val())) { // same username as in receiver
-    $('#send').prop("disabled", !usr.exists);
-    $("label[for=send] img").css("opacity", usr.exists?"1.0":"0.4");
-    $("label[for=send] img").css("filter", usr.exists?"alpha(opacity=100)":"alpha(opacity=40)");
-    if (usr.exists) success("recipient exists");
-    else error("unknown recipient", true);
+
+  /// Record Video from builtin camera
+  function recordvideo() {
+    try {
+      abort()
+      $("#videorecorder").show()
+      recorder = new MediaStreamRecorder({
+        video: {
+          width: {ideal: 180},
+          height: {ideal: 160}
+        },
+        audio: true
+      })
+      recorder.on("ready", function() {
+        $("#videorecorder video").attr("src", recorder.preview())
+        $("#videorecorder video").css("width", 180)
+        $("#videorecorder video").css("height", 160)
+        $("#videorecorder video").attr("width", 180)
+        $("#videorecorder video").attr("height", 160)
+        recorder.start()
+      })
+    } catch (e) {
+      console.log(e)
+      error("cannot access camera", true)
+    }
   }
-  if (userMap == null) {
-    if (localStorage.userMap) {
-      userMap = JSON.parse(localStorage.userMap);
+
+  function previewfile(content, type, name) {
+    if (!name) name = guessfilename(type)
+    if (type.match('^image/')) {
+      var img = document.createElement("img")
+      img.onload = function() { // resize image to maximum 400px
+        var MAX = 400
+        var width = img.width
+        var height = img.height
+        if (width > MAX) {
+          height *= MAX / width
+          width = MAX
+        }
+        if (height > MAX) {
+          width *= MAX / height
+          height = MAX
+        }
+        var canvas = document.createElement("canvas")
+        canvas.width = width
+        canvas.height = height
+        var ctx = canvas.getContext("2d")
+        ctx.drawImage(img, 0, 0, width, height)
+        img.onload = function() {
+          filecontent.push({name: name, type: type, content: img.src})
+          $("#preview").append(img)
+          success('image is ready to be sent')
+        }
+        img.src = canvas.toDataURL(file.type)
+        img.title = name+"\n"+size(img.src.length)
+      }
+      img.src=content
+    } else if (type.match('^video/')) {
+      filecontent.push({name: name, type: type, content: content})
+      var video = document.createElement("video")
+      video.setAttribute("controls", "controls")
+      video.setAttribute("loop", "loop")
+      video.setAttribute("src", content)
+      video.setAttribute("title", name+"\n"+size(content.length))
+      $("#preview").append(video)
     } else {
-      userMap = new Array();
+      filecontent.push({name: name, type: type, content: content})
+      var img = document.createElement("img")
+      img.src = "images/Document_sans_PICOL-PIctorial-COmmunication-Language.svg"
+      img.title = name+"\n"+size(content.length)
+      $("#preview").append(img)
     }
   }
-  if (usr.exists && usr.pubkey && userMap[usr.name] != usr.pubkey) {
-    userMap[usr.name] = usr.pubkey;
-    $("#allusers").append('option value="'+htmlenc(usr.name)+'"')
-    localStorage.userMap = JSON.stringify(userMap);
+
+  /// Upload Attachment
+  /** Prepares attachment to be sent in a message. If the attachment is
+     an image, it resizes the image to 400px on the lager side.
+
+     By now, only images are supported.
+
+     Stores data in global variable @ref filecontent. */
+  function fileupload(evt) {
+    if (!window.FileReader)
+      return error("your browser does not support file upload", true)
+    for (var i=0, f; f=evt.target.files[i]; ++i) {
+      var file = f
+      var reader = new FileReader()
+      reader.onload = function(evt) {
+        if (evt.target.error) return error("error reading file", true)
+        if (evt.target.readyState==0) return notice("waiting for data …")
+        if (evt.target.readyState==1) return notice("loading data …")
+        previewfile(evt.target.result, file.type, file.name)
+      }
+      reader.readAsDataURL(file)
+    }
   }
-}
 
-function queryuser(usr) {
-  console.log("query user: "+uid(usr));
-  socket.emit("user", uid(usr));
-}
+  /// Sets Receiver's Name
+  /** Called when clicked on a receiver's name. Sets focus to the
+     message text field.
 
-/// Get a user's public key.
-/** The first time, gets it from the server, later from the cache. */
-function getPublicKey(user) {
-  var deferredObject = $.Deferred();
-  if (userMap && userMap[user]) deferredObject.resolve(userMap[user]);
-  else deferredObject.reject("unknown user");
-  return deferredObject.promise();
-}
-
-/// Received a list of messages from server
-function messages(msgs) {
-  console.log("rcv-> messages("+msgs.length+")");
-  if (!password || !privateKey())
-    return setTimeout(function() {emit("messages");}, 1000); // try again later
-  status("allmessages");
-  notice("load messages, please wait …");
-  msgs.forEach(function(msg) {message(msg, true);});
-  status("chat");
-}
+     @param name The receiver's name. */
+  function setreceiver(name) {
+    $("#recv").val(name)
+    checkpartner(name)
+    $("#msg").focus()
+  }
 
-/// Received a message from server
-function message(m, internal) {
-  if (!internal) console.log("rcv-> message("+m.user+")");
-  if (!password || !privateKey()) return;
-  var key=openpgp.key.readArmored(m.pubkey);
-  if (key.err) return error("key of sender unreadable", true);
-  var message = openpgp.message.readArmored(m.msg);
-  var privkey = privateKey().keys[0];
-  if (privkey.decrypt(password)) // prepare own key
-    openpgp.decrypt({
-      privateKeys: privkey,
-      publicKeys: key.keys,
-      message: message
-    }).then(function(msg) { // decryption succeded
-      // prepend message to list of messages
-      var message = JSON.parse(msg.text);
-      $("#msgs") // todo: check msg.signatures[0].valid
-        .prepend('<div id="id'+(m.id)+'" class="msg '+
-                           (m.user==userid()?"me":"other")+
-                 '"><div class="header">'+
-                 '<span class="date">'+
-                           (new Date(m.time)).toLocaleString()+
-                 '</span><span class="sender">'+
-                 '<a href="javascript:void(0)" '+
-                 'onclick="setreceiver(this.innerHTML)">'+
-                 htmlenc(m.user)+
-                 '</a>'+(message.receiver?' → <a href="javascript:void(0)" '+
-                                          'onclick="setreceiver(this.innerHTML)">'
-                                         +htmlenc(message.receiver)+'</a>':"")+
-                 '</span></div>'+
-                 '<div class="text">'+
-                 htmlenc(message.text)+
-                 '</div></div><div class="clear"/>');
-      // show attachments
-      attachments(message.files, '#id'+m.id+' .text', m.user, new Date(m.time));
-      // calculate and show emoticons
-      $('#id'+m.id).emoticonize();
-      if (!internal) beep(m.user);
-    }).catch(function(e) {
-      // not for me
-      success();
-    });
-}
+  var userMap = null
+  function users(userlist) {
+    console.log("rcv-> users")
+    userMap = new Array()
+    $("#allusers").empty()
+    userlist.forEach(function(usr) {
+      userMap[usr.name] = usr.pubkey
+      $("#allusers").append('<option value="'+htmlenc(usr.name)+'">')
+      $("#allusers").hide()
+      console.log("   user: "+usr.name)
+    })
+    localStorage.userMap = JSON.stringify(userMap)
+  }
 
-/// Send Message To Server
-/** User wants to send a message. Encrypt message with own private and
-   the receiver's public key, then send it to the server. */
-function sendmessage(recv, txt) {
-  notice("1/3 preparing message …");
-  $("#message").prop(":disabled", true);
-  getPublicKey(recv) // get receiver's public key
-    .done(function(pk) {
-      var key=openpgp.key.readArmored(pk);
-      if (!pk||key.err) {
-        $("#message").prop(":disabled", false);
-        error("receiver's key not found", true);
-        return;
+  function user(usr) {
+    if (usr.exists) console.log("rcv-> user("+usr.name+")")
+    else console.log("rcv-> user("+usr.name+"): name is available")
+    if ($("#newuser").is(":visible") && usr.name==uid($('#user').val())) {
+      // same username as in the create user form
+      $("#createuser").prop("disabled", usr.exists) // todo: check password
+      if (!usr.exists) {
+        username = usr.name
+        success("user name "+usr.name+" is available")
+      } else {
+        username = null
+        error("user name "+usr.name+" is in use", true)
       }
-      var privkey = privateKey().keys[0];
-      privkey.decrypt(password); // get own private key ready
-      var message = JSON.stringify({receiver: recv, text: txt, files: filecontent});
-      notice("2/3 encrypting message …");
-      openpgp.encrypt({publicKeys: key.keys.concat(publicKey().keys),
-                      privateKeys: privkey,
-                      data: message,
-                       armor: false})
-             .then(function(msg) { // message is encrypted
-               notice("3/3 sending message …");
-               emit("message", {user: userid(), content: msg});
-               clearmessage();
-             })
-             .catch(function(e) {
-               $("#message").prop(":disabled", false);
-               error("encryption of message failed", true);
-             });
-    })
-    .fail(function(e) {
-      $("#message").prop(":disabled", false);
-      error("user not found", true);
-    });
-}
+    }
+    if ($("#chat").is(":visible") && usr.name==uid($("#recv").val())) { // same username as in receiver
+      $('#send').prop("disabled", !usr.exists)
+      $("label[for=send] img").css("opacity", usr.exists?"1.0":"0.4")
+      $("label[for=send] img").css("filter", usr.exists?"alpha(opacity=100)":"alpha(opacity=40)")
+      if (usr.exists) success("recipient exists")
+      else error("unknown recipient", true)
+    }
+    if (userMap == null) {
+      if (localStorage.userMap) {
+        userMap = JSON.parse(localStorage.userMap)
+      } else {
+        userMap = new Array()
+      }
+    }
+    if (usr.exists && usr.pubkey && userMap[usr.name] != usr.pubkey) {
+      userMap[usr.name] = usr.pubkey
+      $("#allusers").append('option value="'+htmlenc(usr.name)+'"')
+      localStorage.userMap = JSON.stringify(userMap)
+    }
+  }
 
-/// Check And Set Password
-/** Check if given password matches to decrypt the private key. If so,
-   store it in global temporary variable @ref password and start the
-   chat. The password matches, when the private key can be decrypted.
-
-   @param pwd The password to check. */
-function setpw(pwd) {
-  if (privateKey().keys[0].decrypt(pwd)) {
-    success("password matches");
-    $("#removeKey").hide();
-    password = pwd;
-    chat();
-  } else {
-    notice("password does not match");
+  function queryuser(usr) {
+    console.log("query user: "+uid(usr))
+    socket.emit("user", uid(usr))
   }
-}
 
-/// Create Password Entry Field
-/** Asks user for password. When user starts to enter it, it is
-   permanentely checked in setpw(). As soon as the password matches,
-   setpw() continues automatically. No submit is required by the
-   user. */
-function getpwd() {
-  if (password) return;
-  $("#removeKey").show();
-  status("getpwd");
-}
+  /// Get a user's public key.
+  /** The first time, gets it from the server, later from the cache. */
+  function getPublicKey(user) {
+    var deferredObject = $.Deferred()
+    if (userMap && userMap[user]) deferredObject.resolve(userMap[user])
+    else deferredObject.reject("unknown user")
+    return deferredObject.promise()
+  }
 
-function deleteUser() {
-  var uid = userid();
-  localStorage.removeItem(pubkey);
-  localStorage.removeItem(privkey);
-  error("user "+uid+" permanentely lost");
-}
+  /// Received a list of messages from server
+  function messages(msgs) {
+    console.log("rcv-> messages("+msgs.length+")")
+    if (!password || !privateKey())
+      return setTimeout(function() {emit("messages")}, 1000) // try again later
+    status("allmessages")
+    notice("load messages, please wait …")
+    msgs.forEach(function(msg) {message(msg, true)})
+    status("chat")
+  }
 
-function removeKey() {
-  togglemenu();
-  $("#removeKey").hide();
-  status('forgotpassword');
-}
+  /// Received a message from server
+  function message(m, internal) {
+    if (!internal) console.log("rcv-> message("+m.user+")")
+    if (!password || !privateKey()) return
+    var key=openpgp.key.readArmored(m.pubkey)
+    if (key.err) return error("key of sender unreadable", true)
+    var message = openpgp.message.readArmored(m.msg)
+    var privkey = privateKey().keys[0]
+    if (privkey.decrypt(password)) // prepare own key
+      openpgp.decrypt({
+        privateKeys: privkey,
+        publicKeys: key.keys,
+        message: message
+      }).then(function(msg) { // decryption succeded
+        openpgp.decrypt({
+          privateKeys: privkey,
+          publicKeys: key.keys,
+          message: message
+        }).then(function(msg) { // decryption succeded
+          // prepend message to list of messages
+          var message = JSON.parse(msg.text)
+          $("#msgs") // todo: check msg.signatures[0].valid
+            .prepend('<div id="id'+(m.id)+'" class="msg '+
+                            (m.user==userid()?"me":"other")+
+                     '"><div class="header">'+
+                     '<span class="date">'+
+                            (new Date(m.time)).toLocaleString()+
+                     '</span><span class="sender">'+
+                     '<a href="javascript:void(0)" '+
+                     'onclick="setreceiver(this.innerHTML)">'+
+                     htmlenc(m.user)+
+                     '</a>'+(message.receiver?' → <a href="javascript:void(0)" '+
+                                              'onclick="setreceiver(this.innerHTML)">'
+                                             +htmlenc(message.receiver)+'</a>':"")+
+                     '</span></div>'+
+                     '<div class="text">'+
+                     htmlenc(message.text)+
+                     '</div></div><div class="clear"/>')
+          // show attachments
+          attachments(message.files, '#id'+m.id+' .text', m.user, new Date(m.time))
+          // calculate and show emoticons
+          $('#id'+m.id).emoticonize()
+          if (!internal) beep(m.user)
+        }).catch(function(e) {
+          // not for me
+          success()
+        })
+      }
 
-/// Main Chat Window
-/** Gets chat widgets from server and displays them. Starts timer for
-   get() which polls for new messages. */
-var firsttime = true;
-function chat() {
-  if (!password) return getpwd();
-  status("chat");
-  if (firsttime && $('#msgs').is(':empty')) {
-    firsttime = false;
-    notice("getting previous messages, please wait …");
-    emit("messages");
-  }
-}
+        /// Send Message To Server
+        /** User wants to send a message. Encrypt message with own private and
+           the receiver's public key, then send it to the server. */
+        function sendmessage(recv, txt) {
+          notice("1/3 preparing message …")
+          $("#message").prop(":disabled", true)
+          getPublicKey(recv) // get receiver's public key
+            .done(function(pk) {
+              var key=openpgp.key.readArmored(pk)
+              if (!pk||key.err) {
+                $("#message").prop(":disabled", false)
+                error("receiver's key not found", true)
+                return
+              }
+              var privkey = privateKey().keys[0]
+              privkey.decrypt(password) // get own private key ready
+              var message = JSON.stringify({receiver: recv, text: txt, files: filecontent})
+              notice("2/3 encrypting message …")
+              openpgp.encrypt({publicKeys: key.keys.concat(publicKey().keys),
+                               privateKeys: privkey,
+                               data: message,
+                               armor: false})
+                     .then(function(msg) { // message is encrypted
+                       notice("3/3 sending message …")
+                       emit("message", {user: userid(), content: msg})
+                       clearmessage()
+                     })
+                     .catch(function(e) {
+                       $("#message").prop(":disabled", false)
+                       error("encryption of message failed", true)
+                     })
+            })
+            .fail(function(e) {
+              $("#message").prop(":disabled", false)
+              error("user not found", true)
+            })
+        }
 
-/// Login User
-/** This is not really a login, it is just some kind of validation.
-   The server does not care if a user is online or not, it is only
-   interesting to the client to make sure, everything is fine. User
-   is logged in the following way: User name and public key are sent
-   to the server. If the user name exists on the server and the
-   public key is the same, the user is considered logged in, his
-   credentials seem to be valid. If user does not yet exits on
-   server, it is created now. If user exists, but public key is
-   different, then this is a complete failure, something went
-   terribly wrong. */
-function login() {
-  $("#username").html(userid()+"@"+hostname);
-  emit("login", {name: userid(),
-                 pubkey: localStorage.pubkey});
-  success("login sent to server");
-}
+        /// Check And Set Password
+        /** Check if given password matches to decrypt the private key. If so,
+           store it in global temporary variable @ref password and start the
+           chat. The password matches, when the private key can be decrypted.
+
+           @param pwd The password to check. */
+        function setpw(pwd) {
+          if (privateKey().keys[0].decrypt(pwd)) {
+            success("password matches")
+            $("#removeKey").hide()
+            password = pwd
+            chat()
+          } else {
+            notice("password does not match")
+          }
+        }
 
-/// Get And Display Form To Create New User
-/** Shows user creation form. On submit, a private key is generated in
-   createkeypair(), then login() creates the user. */
-function newuser() {
-  status("newuser");
-}
+        /// Create Password Entry Field
+        /** Asks user for password. When user starts to enter it, it is
+           permanentely checked in setpw(). As soon as the password matches,
+           setpw() continues automatically. No submit is required by the
+           user. */
+        function getpwd() {
+          if (password) return
+          $("#removeKey").show()
+          status("getpwd")
+        }
 
-/// Check if local storage is available
-function checkLocalStorage() {
-  var test = 'test';
-  try {
-    localStorage.setItem(test, test);
-    localStorage.removeItem(test);
-    return true;
-  } catch(e) {
-    status("nolocalstorage");
-    error("local storage not available");
-  }
-  return false;
-}
+        function deleteUser() {
+          var uid = userid()
+          localStorage.removeItem(pubkey)
+          localStorage.removeItem(privkey)
+          error("user "+uid+" permanentely lost")
+        }
 
-/// Initial Function: Startup
-/** Decide whether to login or to create a new user */
-function start() {
-  $("#menu").hide();
-  //status("startup");
-  if (checkLocalStorage())
-    try {
-      if (!userid()) {
-        newuser();
-      } else {
-        login();
-      }
-    } catch (m) {
-      console.log(m.stack);
-      error(m);
-    }
-}
+        function removeKey() {
+          togglemenu()
+          $("#removeKey").hide()
+          status('forgotpassword')
+        }
 
-function init() {
-  /// On Load, Call @ref start
-  $(window.onbeforeunload = function() {
-    return "Are you sure you want to navigate away?";
-  });
-  /// Allow Running in Background on Android
-  document.addEventListener('deviceready', function () {
-    if (cordova && cordova.plugins.backgroundMode) {
-      cordova.plugins.backgroundMode.enable();
-    }
-  }, false);
-  socket.io.on("connect", connected);
-  socket.io.on("reconnect", connected);
-  socket.io.on("disconnect", disconnected);
-  socket.io.on("error", disconnected);
-  socket.on("login", loggedin);
-  socket.on("fail", fail);
-  socket.on("user", user);
-  socket.on("users", users);
-  socket.on("message", message);
-  socket.on("messages", messages);
-  connectionstatus();
-  if (openpgp.initWorker("openpgp.worker.min.js"))
-    console.log("asynchronous openpgp enabled");
-  else
-    console.log("asynchronous openpgp failed");
-  emit('users');
-  start();
-}
+        /// Main Chat Window
+        /** Gets chat widgets from server and displays them. Starts timer for
+           get() which polls for new messages. */
+        var firsttime = true
+        function chat() {
+          if (!password) return getpwd()
+          status("chat")
+          if (firsttime && $('#msgs').is(':empty')) {
+            firsttime = false
+            notice("getting previous messages, please wait …")
+            emit("messages")
+          }
+        }
+
+        /// Login User
+        /** This is not really a login, it is just some kind of validation.
+           The server does not care if a user is online or not, it is only
+           interesting to the client to make sure, everything is fine. User
+           is logged in the following way: User name and public key are sent
+           to the server. If the user name exists on the server and the
+           public key is the same, the user is considered logged in, his
+           credentials seem to be valid. If user does not yet exits on
+           server, it is created now. If user exists, but public key is
+           different, then this is a complete failure, something went
+           terribly wrong. */
+        function login() {
+          $("#username").html(userid()+"@"+hostname)
+          emit("login", {name: userid(),
+                         pubkey: localStorage.pubkey})
+          success("login sent to server")
+        }
+
+        /// Get And Display Form To Create New User
+        /** Shows user creation form. On submit, a private key is generated in
+           createkeypair(), then login() creates the user. */
+        function newuser() {
+          status("newuser")
+        }
+
+        /// Check if local storage is available
+        function checkLocalStorage() {
+          var test = 'test'
+          try {
+            localStorage.setItem(test, test)
+            localStorage.removeItem(test)
+            return true
+          } catch(e) {
+            status("nolocalstorage")
+            error("local storage not available")
+          }
+          return false
+        }
+
+        /// Initial Function: Startup
+        /** Decide whether to login or to create a new user */
+        function start() {
+          $("#menu").hide()
+          //status("startup")
+          if (checkLocalStorage())
+            try {
+              if (!userid()) {
+                newuser()
+              } else {
+                login()
+              }
+            } catch (m) {
+              console.log(m.stack)
+              error(m)
+            }
+        }
+
+        function init() {
+          /// On Load, Call @ref start
+          $(window.onbeforeunload = function() {
+            return "Are you sure you want to navigate away?"
+          })
+          /// Allow Running in Background on Android
+          document.addEventListener('deviceready', function () {
+            if (cordova && cordova.plugins.backgroundMode) {
+              cordova.plugins.backgroundMode.enable()
+            }
+          }, false)
+          connectionstatus()
+          if (openpgp.initWorker("openpgp.worker.min.js"))
+            console.log("asynchronous openpgp enabled")
+          else
+            console.log("asynchronous openpgp failed")
+          emit('users')
+          start()
+        }
 
-/// Start Main Loop
-$(init);
+        /// Start Main Loop
+        $(init)
diff --git a/nodejs/public/sounds/A-Tone-His_Self-1266414414.mp3 b/nodejs/public/sounds/beep.mp3
similarity index 100%
rename from nodejs/public/sounds/A-Tone-His_Self-1266414414.mp3
rename to nodejs/public/sounds/beep.mp3
diff --git a/nodejs/views/index.ejs b/nodejs/views/index.ejs
index 07b8856..6726f08 100644
--- a/nodejs/views/index.ejs
+++ b/nodejs/views/index.ejs
@@ -30,7 +30,7 @@
     
     <ul id="menu" style="display: none">
       <li onclick="backup()">Download Backup</li>
-      <li class="toolbutton"><label for="restore">Restore Backup</label><input autocomplete="off" type="file" accept="*.bak" id="restore" /></li>
+      <li id="restore-menu-item" class="toolbutton"><label for="restore">Restore Backup</label><input autocomplete="off" type="file" accept="*.bak" id="restore" /></li>
       <li id="groups" onclick="groups()">Edit Groups</li>
       <li id="removeKey" style="display: none" onclick="removeKey()">Password Forgotten</li>
       <li id="android-download" href="safechat.apk"><a href="safechat.apk">Download Android-App</a></li>
@@ -182,6 +182,25 @@
         </div>
       </div>
 
+      <!--                                                    Fatal: Abort -->
+
+      <div id="fatal">
+        <h2 id="fatal-msg">Failure</h2>
+        <p>The SafeChat has been aborted due to a fatal error.</p>
+        <p>There is a problem in your browser. Please try to reload. If the problem persists, please update your web browser or try SafeChat in another browser.</p>
+        <p>The following java script features are required:</p>
+        <ul class="features">
+          <li id="localstorage">Local Storage</li>
+          <li id="indexeddb">Indexed DB</li>
+          <li id="randomvalues">Cryptography: Random Values</li>
+        </ul>
+        <p>The following java script features are optional:</p>
+        <ul class="features">
+          <li id="vibrate">Vibration (vibrates when new message arrives)</li>
+          <li id="filereader">File Reader (required to restore backup)</li>
+        </ul>
+      </div>
+
       <!--                                                    Error: Missing JavaScript -->
       <noscript>
         <h2>JavasScript Required!</h2>
@@ -193,12 +212,6 @@
         <p><a href="<%= package.documentation %>" target="_blank">more information</a></p>
       </noscript>
 
-      <!--                                                  Error: Missing LocalStorage -->
-      <div id="nolocalstorage" style="display: none">
-        <p>No access to local storage. Please allow access to local
-          storage, i.e. do not block cookies.<p>
-      </div>
-
       <!--                                                       Notice: Setup Messages -->
       <div id="allmessages" style="display: none">
         <p>Setting up all previous messages, please wait …</p>