/*
  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/>.
*/

var sha256 = require("jssha256").sha256;

exports.hmac = {
    hmac : function(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 = sha256.digest(opad + sha256.digest(ipad + message));

	return result;
    }
};