/*
  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 pkdbf2 (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);
}