/*
  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 hmac256(key, message) {
    var ipad = "";
    var opad = "";

    for(i=0; i<key.length; i++)
    {
	ipad += String.fromCharCode(key.charCodeAt(i) ^ 0x36);
	opad += String.fromCharCode(key.charCodeAt(i) ^ 0x5c);
    }
    while (ipad.length < 512/8)
    {
	ipad += String.fromCharCode(0x36);
	opad += String.fromCharCode(0x5c);
    }

    result = digest256(opad + digest256(ipad + message));

    return result;
}