/**
* 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');
}