3612fc12dc
and make the high-level API accessible from an asynchronous proxy. Entropy is seeded to worker on each generateKeyPair() call. Allow serialization of packets and custom types for messaging API.
127 lines
4.3 KiB
JavaScript
127 lines
4.3 KiB
JavaScript
// GPG4Browsers - An OpenPGP implementation in javascript
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// Copyright (C) 2011 Recurity Labs GmbH
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public
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// License as published by the Free Software Foundation; either
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// version 2.1 of the License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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/**
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* Implementation of the Sym. Encrypted Integrity Protected Data
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* Packet (Tag 18)<br/>
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* <br/>
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* {@link http://tools.ietf.org/html/rfc4880#section-5.13|RFC4880 5.13}:
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* The Symmetrically Encrypted Integrity Protected Data packet is
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* a variant of the Symmetrically Encrypted Data packet. It is a new feature
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* created for OpenPGP that addresses the problem of detecting a modification to
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* encrypted data. It is used in combination with a Modification Detection Code
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* packet.
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* @requires crypto
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* @requires util
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* @requires enums
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* @module packet/sym_encrypted_integrity_protected
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*/
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module.exports = SymEncryptedIntegrityProtected;
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var util = require('../util.js'),
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crypto = require('../crypto'),
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enums = require('../enums.js');
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/**
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* @constructor
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*/
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function SymEncryptedIntegrityProtected() {
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this.tag = enums.packet.symEncryptedIntegrityProtected;
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/** The encrypted payload. */
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this.encrypted = null; // string
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/**
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* If after decrypting the packet this is set to true,
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* a modification has been detected and thus the contents
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* should be discarded.
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* @type {Boolean}
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*/
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this.modification = false;
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this.packets = null;
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}
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SymEncryptedIntegrityProtected.prototype.read = function (bytes) {
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// - A one-octet version number. The only currently defined value is 1.
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var version = bytes.charCodeAt(0);
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if (version != 1) {
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throw new Error('Invalid packet version.');
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}
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// - Encrypted data, the output of the selected symmetric-key cipher
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// operating in Cipher Feedback mode with shift amount equal to the
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// block size of the cipher (CFB-n where n is the block size).
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this.encrypted = bytes.substr(1);
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};
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SymEncryptedIntegrityProtected.prototype.write = function () {
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// 1 = Version
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return String.fromCharCode(1) + this.encrypted;
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};
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SymEncryptedIntegrityProtected.prototype.encrypt = function (sessionKeyAlgorithm, key) {
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var bytes = this.packets.write();
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var prefixrandom = crypto.getPrefixRandom(sessionKeyAlgorithm);
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var prefix = prefixrandom + prefixrandom.charAt(prefixrandom.length - 2) + prefixrandom.charAt(prefixrandom.length -
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1);
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var tohash = bytes;
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// Modification detection code packet.
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tohash += String.fromCharCode(0xD3);
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tohash += String.fromCharCode(0x14);
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tohash += crypto.hash.sha1(prefix + tohash);
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this.encrypted = crypto.cfb.encrypt(prefixrandom,
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sessionKeyAlgorithm, tohash, key, false).substring(0,
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prefix.length + tohash.length);
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};
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/**
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* Decrypts the encrypted data contained in this object read_packet must
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* have been called before
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*
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* @param {module:enums.symmetric} sessionKeyAlgorithm
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* The selected symmetric encryption algorithm to be used
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* @param {String} key The key of cipher blocksize length to be used
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* @return {String} The decrypted data of this packet
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*/
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SymEncryptedIntegrityProtected.prototype.decrypt = function (sessionKeyAlgorithm, key) {
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var decrypted = crypto.cfb.decrypt(
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sessionKeyAlgorithm, key, this.encrypted, false);
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// there must be a modification detection code packet as the
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// last packet and everything gets hashed except the hash itself
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this.hash = crypto.hash.sha1(
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crypto.cfb.mdc(sessionKeyAlgorithm, key, this.encrypted) + decrypted.substring(0, decrypted.length - 20));
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var mdc = decrypted.substr(decrypted.length - 20, 20);
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if (this.hash != mdc) {
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throw new Error('Modification detected.');
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} else
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this.packets.read(decrypted.substr(0, decrypted.length - 22));
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};
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