HORIZON PROJECT

/**

 * Module dependencies.

 */

var crypto = require('crypto');

/**

 * Sign the given `val` with `secret`.

 *

 * @param {String} val

 * @param {String} secret

 * @return {String}

 * @api private

 */

exports.sign = function(val, secret){

  if ('string' != typeof val) throw new TypeError("Cookie value must be provided as a string.");

  if ('string' != typeof secret) throw new TypeError("Secret string must be provided.");

  return val + '.' + crypto

    .createHmac('sha256', secret)

    .update(val)

    .digest('base64')

    .replace(/\=+$/, '');

};

/**

 * Unsign and decode the given `val` with `secret`,

 * returning `false` if the signature is invalid.

 *

 * @param {String} val

 * @param {String} secret

 * @return {String|Boolean}

 * @api private

 */

exports.unsign = function(val, secret){

  if ('string' != typeof val) throw new TypeError("Signed cookie string must be provided.");

  if ('string' != typeof secret) throw new TypeError("Secret string must be provided.");

  var str = val.slice(0, val.lastIndexOf('.'))

    , mac = exports.sign(str, secret);

  return sha1(mac) == sha1(val) ? str : false;

};

/**

 * Private

 */

function sha1(str){

  return crypto.createHash('sha1').update(str).digest('hex');

}