Modified the authentication stuff to grant access not based on plain password authentication but on a kind of 'timed cookies' so the password is not stored in plain text in some browser cookie.

Also modded some random string generation funtions for elegance.

node/db/Pad.js

@@ -489,9 +489,13 @@ Class('Pad', {
       this.passwordHash = password == null ? null : hash(password, generateSalt());
       db.setSub("pad:"+this.id, ["passwordHash"], this.passwordHash);
     }, 
+	getPasswordSalt: function()
+	{
+		return this.passwordHash.split("$")[1];
+	},
     isCorrectPassword: function(password)
     {
-      return compare(this.passwordHash, password)
+      return timeSensitiveCompare(this.passwordHash, password)
     }, 
     isPasswordProtected: function()
     {
@@ -512,17 +516,21 @@ function hash(password, salt)
 function generateSalt()
 {
   var len = 86;
-  var chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz./";
+  var charset = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz./";
   var randomstring = '';
   for (var i = 0; i < len; i++)
   {
-    var rnum = Math.floor(Math.random() * chars.length);
-    randomstring += chars.substring(rnum, rnum + 1);
+    var rnum = Math.floor(Math.random() * charset.length);
+    randomstring += charset[rnum];
   }
   return randomstring;
 }
 
-function compare(hashStr, password)
+/* Compare the timed password hash with the saved value.
+ * If the hash was generated too far in the past, it is rejected. */
+function timeSensitiveCompare(hashStr, password)
 {
-  return hash(password, hashStr.split("$")[1]) === hashStr;  
+  var timestamp = password.split("$")[1];
+  return password === hash(hashStr, timestamp)
+    && timestamp - new Date().getTime() > 0;
 }

node/db/SecurityManager.js

@@ -51,6 +51,7 @@ exports.checkAccess = function (padID, sessionID, token, password, callback)
   var groupID = padID.split("$")[0];
   var padExists = false;
   var validSession = false;
+  var pwsalt;
   var sessionAuthor;
   var tokenAuthor;
   var isPublic;
@@ -131,6 +132,9 @@ exports.checkAccess = function (padID, sessionID, token, password, callback)
         
         //is it password protected?
         isPasswordProtected = pad.isPasswordProtected();
+
+		//get the password salt used by the hash function
+		pwsalt = pad.getPasswordSalt();
         
         //is password correct?
         if(isPasswordProtected && password && pad.isCorrectPassword(password))
@@ -162,13 +166,14 @@ exports.checkAccess = function (padID, sessionID, token, password, callback)
         else if(isPasswordProtected && passwordStatus == "wrong")
         {
           //--> deny access, ask for new password and tell them that the password is wrong
-          statusObject = {accessStatus: "wrongPassword"};
+		  //The salt can be safely shared since it is not secret. It does its job (improving resistence against rainbow table attacks) even when public.
+          statusObject = {accessStatus: "wrongPassword", passwordSalt: pwsalt};
         }
         //- the pad is password protected but no password given
         else if(isPasswordProtected && passwordStatus == "notGiven")
         {
           //--> ask for password
-          statusObject = {accessStatus: "needPassword"};
+          statusObject = {accessStatus: "needPassword", passwordSalt: pwsalt};
         }
         else
         {

static/js/pad2.js

@@ -72,7 +72,7 @@ function randomString()
   for (var i = 0; i < string_length; i++)
   {
     var rnum = Math.floor(Math.random() * chars.length);
-    randomstring += chars.substring(rnum, rnum + 1);
+    randomstring += chars[rnum];
   }
   return "t." + randomstring;
 }
@@ -147,10 +147,22 @@ function getUrlVars()
   return vars;
 }
 
-function savePassword()
+function hash(password, salt)
+{
+	return sha512(password + salt) + "$" + salt;
+}
+
+/* Generate the "timed hash" used to get access.
+ * The password is hashed with the database's salt, afterwards it is hashed again with a timestamp a few days in the future as "salt".
+ * The server checks the two hashe's equality as usual, but also checks whether this timestamp is still in the future (grant access)
+ * or if it has passed (deny access). This provides an saved-password expiry mechanism which is a) independent of the browser's cookie
+ * retention and b) provides some level of security against "cookie stealing" (be it by xss or otherwise): If Eve steals a cookie, she
+ * does "only" get a timed-hash lifetime access to the pad, but *not* the actual password.
+ */
+function savePassword(pwsalt)
 {
   //set the password cookie
-  createCookie("password",$("#passwordinput").val(),null,document.location.pathname);
+  createCookie("password",hash(hash($("#passwordinput").val(), pwsalt), new Date().getTime() + 14 * 24 * 3600 * 1000),null,document.location.pathname); //FIXME some means of configuring this threshold would be really great
   //reload
   document.location=document.location;
 }
@@ -214,13 +226,13 @@ function handshake()
       {
         $("#editorloadingbox").html("<b>You need a password to access this pad</b><br>" +
                                     "<input id='passwordinput' type='password' name='password'>"+
-                                    "<button type='button' onclick='savePassword()'>ok</button>");
+                                    "<button type='button' onclick='savePassword("+obj.passwordSalt+")'>ok</button>");
       }
       else if(obj.accessStatus == "wrongPassword")
       {
-        $("#editorloadingbox").html("<b>You're password was wrong</b><br>" +
+        $("#editorloadingbox").html("<b>Your password was wrong</b><br>" +
                                     "<input id='passwordinput' type='password' name='password'>"+
-                                    "<button type='button' onclick='savePassword()'>ok</button>");
+                                    "<button type='button' onclick='savePassword("+obj.passwordSalt+")'>ok</button>");
       }
     }