Source: keyring/localstore.js

// GPG4Browsers - An OpenPGP implementation in javascript
// Copyright (C) 2011 Recurity Labs GmbH
// 
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
// 
// This library 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
// Lesser General Public License for more details.
// 
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

/**
 * The class that deals with storage of the keyring. Currently the only option is to use HTML5 local storage.
 * @requires openpgp
 * @module keyring/localstore
 */

var openpgp = require('openpgp');

module.exports = function () {
  /**
   * Load the keyring from HTML5 local storage and initializes this instance.
   * @return {Array<module:key~Key>} array of keys retrieved from localstore
   */
  this.load = function () {
    var armoredKeys = JSON.parse(window.localStorage.getItem("armoredKeys"));
    var keys = [];
    if (armoredKeys !== null && armoredKeys.length !== 0) {
      var key;
      for (var i = 0; i < armoredKeys.length; i++) {
        key = openpgp.key.readArmored(armoredKeys[i]);
        keys.push(key);
      }
    }
    return keys;
  }

  /**
   * Saves the current state of the keyring to HTML5 local storage.
   * The privateKeys array and publicKeys array gets Stringified using JSON
   * @param {Array<module:key~Key>} keys array of keys to save in localstore
   */
  this.store = function (keys) {
    var armoredKeys = [];
    for (var i = 0; i < keys.length; i++) {
      armoredKeys.push(keys[i].armor());
    }
    window.localStorage.setItem("armoredKeys", JSON.stringify(armoredKeys));
  }
};