Change protocol version (3 -> 4) : PKDBF2 is renamed in PBKDF2. This also avoid mismatch with new encryption system

server/resources/pbkdf2.js

@@ -0,0 +1,51 @@
+/*
+  Copyright (C) 2013 Grégory Soutadé
+  
+  This file is part of gPass.
+  
+  gPass is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+  
+  gPass is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+  
+  You should have received a copy of the GNU General Public License
+  along with gPass.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+function pbkdf2 (password, salt, iterations, outlen) {
+    var result = "";
+    var temp = "";
+    var temp2 = "";
+    var temp_res = "";
+    var temp_res2 = "";
+
+    for (i=1; result.length < outlen; i++)
+    {
+	temp = hmac256(password, salt + 
+		       String.fromCharCode((i & 0xff000000) >> 24) +
+		       String.fromCharCode((i & 0x00ff0000) >> 16) +
+		       String.fromCharCode((i & 0x0000ff00) >>  8) +
+		       String.fromCharCode((i & 0x000000ff) >>  0)
+		       );
+	temp_res = temp;
+
+	for(a=1; a<iterations; a++)
+	{
+	    temp2 = hmac256(password, temp);
+	    temp_res2 = "";
+	    for(b = 0; b<temp_res.length; b++)
+		temp_res2 += String.fromCharCode(temp_res.charCodeAt(b) ^ temp2.charCodeAt(b));
+	    temp_res = temp_res2;
+	    temp = temp2;
+	}
+
+	result += temp_res;
+    }
+
+    return result.substr(0, outlen);
+}