Support AES-GCM with AEAD Protected Data Packets

Closes openpgpjs/openpgpjs#421

src/config/config.js

@@ -37,6 +37,7 @@ export default {
   prefer_hash_algorithm: enums.hash.sha256,
   encryption_cipher: enums.symmetric.aes256,
   compression: enums.compression.zip,
+  aead_protect: true, // use Authenticated Encryption with Additional Data (AEAD) protection for symmetric encryption
   integrity_protect: true, // use integrity protection for symmetric encryption
   ignore_mdc_error: false, // fail on decrypt if message is not integrity protected
   rsa_blinding: true,

src/crypto/gcm.js

@@ -0,0 +1,105 @@
+// OpenPGP.js - An OpenPGP implementation in javascript
+// Copyright (C) 2016 Tankred Hase
+//
+// 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 3.0 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
+
+/**
+ * @fileoverview This module wraps native AES-GCM en/decryption for both
+ * the WebCrypto api as well as node.js' crypto api.
+ */
+
+'use strict';
+
+import util from '../util.js';
+import asmCrypto from 'asmcrypto-lite';
+const webCrypto = util.getWebCrypto();
+const nodeCrypto = util.getNodeCrypto();
+const Buffer = util.getNodeBuffer();
+
+export const ivLength = 12;
+
+/**
+ * Encrypt plaintext input.
+ * @param  {String}     cipher      The symmetric cipher algorithm to use
+ * @param  {Uint8Array} plaintext   The cleartext input to be encrypted
+ * @param  {Uint8Array} key         The encryption key
+ * @param  {Uint8Array} iv          The initialization vector (12 bytes)
+ * @return {Promise<Uint8Array>}    The ciphertext output
+ */
+export function encrypt(cipher, plaintext, key, iv) {
+  if (cipher.substr(0,3) !== 'aes') {
+    return Promise.reject(new Error('Invalid cipher for GCM mode'));
+  }
+
+  if (webCrypto) { // native WebCrypto api
+    const keyOptions = {
+      name: 'AES-GCM'
+    },
+    encryptOptions = {
+      name: 'AES-GCM',
+      iv: iv
+    };
+    return webCrypto.importKey('raw', key, keyOptions, false, ['encrypt']).then(keyObj => {
+      return webCrypto.encrypt(encryptOptions, keyObj, plaintext);
+    }).then(ciphertext => {
+      return new Uint8Array(ciphertext);
+    });
+
+  } else if(nodeCrypto) { // native node crypto library
+    let cipherObj = new nodeCrypto.createCipheriv('aes-' + cipher.substr(3,3) + '-gcm', new Buffer(key), new Buffer(iv));
+    let encrypted = Buffer.concat([cipherObj.update(new Buffer(plaintext)), cipherObj.final()]);
+    return Promise.resolve(new Uint8Array(encrypted));
+
+  } else { // asm.js fallback
+    return Promise.resolve(asmCrypto.AES_GCM.encrypt(plaintext, key, iv));
+  }
+}
+
+/**
+ * Decrypt ciphertext input
+ * @param  {String}     cipher       The symmetric cipher algorithm to use
+ * @param  {Uint8Array} ciphertext   The ciphertext input to be decrypted
+ * @param  {Uint8Array} key          The encryption key
+ * @param  {Uint8Array} iv           The initialization vector (12 bytes)
+ * @return {Promise<Uint8Array>}     The plaintext output
+ */
+export function decrypt(cipher, ciphertext, key, iv) {
+  if (cipher.substr(0,3) !== 'aes') {
+    return Promise.reject(new Error('Invalid cipher for GCM mode'));
+  }
+
+  if (webCrypto) { // native WebCrypto api
+    const keyOptions = {
+      name: 'AES-GCM'
+    },
+    decryptOptions = {
+      name: 'AES-GCM',
+      iv: iv
+    };
+    return webCrypto.importKey('raw', key, keyOptions, false, ['decrypt']).then(keyObj => {
+      return webCrypto.decrypt(decryptOptions, keyObj, ciphertext);
+    }).then(plaintext => {
+      return new Uint8Array(plaintext);
+    });
+
+  } else if(nodeCrypto) { // native node crypto library
+    let decipherObj = new nodeCrypto.createDecipheriv('aes-' + cipher.substr(3,3) + '-gcm', new Buffer(key), new Buffer(iv));
+    let decrypted = Buffer.concat([decipherObj.update(new Buffer(ciphertext)), decipherObj.final()]);
+    return Promise.resolve(new Uint8Array(decrypted));
+
+  } else { // asm.js fallback
+    return Promise.resolve(asmCrypto.AES_GCM.decrypt(ciphertext, key, iv));
+  }
+}

src/crypto/index.js

@@ -8,6 +8,7 @@
 import cipher from './cipher';
 import hash from './hash';
 import cfb from './cfb';
+import * as gcm from './gcm';
 import publicKey from './public_key';
 import signature from './signature';
 import random from './random';
@@ -21,6 +22,8 @@ const mod = {
   hash: hash,
   /** @see module:crypto/cfb */
   cfb: cfb,
+  /** @see module:crypto/aes-gcm */
+  gcm: gcm,
   /** @see module:crypto/public_key */
   publicKey: publicKey,
   /** @see module:crypto/signature */

src/crypto/random.js

@@ -91,6 +91,7 @@ export default {
     } else {
       throw new Error('No secure random number generator available.');
     }
+    return buf;
   },
 
   /**

src/enums.js

@@ -94,7 +94,8 @@ export default {
     publicSubkey: 14,
     userAttribute: 17,
     symEncryptedIntegrityProtected: 18,
-    modificationDetectionCode: 19
+    modificationDetectionCode: 19,
+    symEncryptedAEADProtected: 20 // see IETF draft: https://tools.ietf.org/html/draft-ford-openpgp-format-00#section-2.2.1
   },
 
   /** Data types in the literal packet

src/message.js

@@ -96,15 +96,23 @@ Message.prototype.decrypt = function(privateKey, sessionKey, password) {
   if (!keyObj || !util.isUint8Array(keyObj.data) || !util.isString(keyObj.algorithm)) {
     throw new Error('Invalid session key for decryption.');
   }
-  var symEncryptedPacketlist = this.packets.filterByTag(enums.packet.symmetricallyEncrypted, enums.packet.symEncryptedIntegrityProtected);
+
+  var symEncryptedPacketlist = this.packets.filterByTag(
+    enums.packet.symmetricallyEncrypted,
+    enums.packet.symEncryptedIntegrityProtected,
+    enums.packet.symEncryptedAEADProtected
+  );
+
   if (symEncryptedPacketlist.length !== 0) {
     var symEncryptedPacket = symEncryptedPacketlist[0];
-    symEncryptedPacket.decrypt(keyObj.algorithm, keyObj.data);
+    return symEncryptedPacket.decrypt(keyObj.algorithm, keyObj.data).then(() => {
       var resultMsg = new Message(symEncryptedPacket.packets);
       // remove packets after decryption
       symEncryptedPacket.packets = new packet.List();
       return resultMsg;
+    });
   }
+  return Promise.resolve();
 };
 
 /**
@@ -219,18 +227,21 @@ Message.prototype.encrypt = function(keys, passwords) {
   var packetlist = msg.packets;
 
   var symEncryptedPacket;
-  if (config.integrity_protect) {
+  if (config.aead_protect) {
+    symEncryptedPacket = new packet.SymEncryptedAEADProtected();
+  } else if (config.integrity_protect) {
     symEncryptedPacket = new packet.SymEncryptedIntegrityProtected();
   } else {
     symEncryptedPacket = new packet.SymmetricallyEncrypted();
   }
   symEncryptedPacket.packets = this.packets;
-  symEncryptedPacket.encrypt(enums.read(enums.symmetric, symAlgo), sessionKey);
+
+  return symEncryptedPacket.encrypt(enums.read(enums.symmetric, symAlgo), sessionKey).then(() => {
     packetlist.push(symEncryptedPacket);
     // remove packets after encryption
     symEncryptedPacket.packets = new packet.List();
-
     return msg;
+  });
 };
 
 /**

src/openpgp.js

@@ -169,17 +169,16 @@ export function decryptKey({ privateKey, passphrase }) {
 export function encrypt({ data, publicKeys, privateKeys, passwords, filename, armor=true }) {
   checkData(data); publicKeys = toArray(publicKeys); privateKeys = toArray(privateKeys); passwords = toArray(passwords);
 
-  if (asyncProxy) { // use web worker if available
+  if (!util.getWebCrypto() && asyncProxy) { // use web worker if web crypto apis are not supported
     return asyncProxy.delegate('encrypt', { data, publicKeys, privateKeys, passwords, filename, armor });
   }
 
-  return execute(() => {
-
   let message = createMessage(data, filename);
   if (privateKeys) { // sign the message only if private keys are specified
     message = message.sign(privateKeys);
   }
-    message = message.encrypt(publicKeys, passwords);
+
+  return message.encrypt(publicKeys, passwords).then(message => {
 
     if(armor) {
       return {
@@ -190,7 +189,7 @@ export function encrypt({ data, publicKeys, privateKeys, passwords, filename, ar
       message: message
     };
 
-  }, 'Error encrypting message');
+  }).catch(onError.bind(null, 'Error encrypting message'));
 }
 
 /**
@@ -209,20 +208,19 @@ export function encrypt({ data, publicKeys, privateKeys, passwords, filename, ar
 export function decrypt({ message, privateKey, publicKeys, sessionKey, password, format='utf8' }) {
   checkMessage(message); publicKeys = toArray(publicKeys);
 
-  if (asyncProxy) { // use web worker if available
+  if (!util.getWebCrypto() && asyncProxy) { // use web worker if web crypto apis are not supported
     return asyncProxy.delegate('decrypt', { message, privateKey, publicKeys, sessionKey, password, format });
   }
 
-  return execute(() => {
+  return message.decrypt(privateKey, sessionKey, password).then(message => {
 
-    message = message.decrypt(privateKey, sessionKey, password);
     const result = parseMessage(message, format);
     if (publicKeys && result.data) { // verify only if publicKeys are specified
       result.signatures = message.verify(publicKeys);
     }
     return result;
 
-  }, 'Error decrypting message');
+  }).catch(onError.bind(null, 'Error decrypting message'));
 }
 
 

src/packet/all_packets.js

@@ -12,6 +12,8 @@ import * as packets from './all_packets.js'; // re-import module to parse packet
 export { default as Compressed } from './compressed.js';
 /** @see module:packet/sym_encrypted_integrity_protected */
 export { default as SymEncryptedIntegrityProtected } from './sym_encrypted_integrity_protected.js';
+/** @see module:packet/sym_encrypted_aead_protected */
+export { default as SymEncryptedAEADProtected } from './sym_encrypted_aead_protected.js';
 /** @see module:packet/public_key_encrypted_session_key */
 export { default as PublicKeyEncryptedSessionKey } from './public_key_encrypted_session_key.js';
 /** @see module:packet/sym_encrypted_session_key */

src/packet/sym_encrypted_aead_protected.js

@@ -0,0 +1,66 @@
+// OpenPGP.js - An OpenPGP implementation in javascript
+// Copyright (C) 2016 Tankred Hase
+//
+// 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 3.0 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
+
+/**
+ * Implementation of the Symmetrically Encrypted AEAD Protected Data Packet <br/>
+ * <br/>
+ * {@link https://tools.ietf.org/html/draft-ford-openpgp-format-00#section-2.1}: AEAD Protected Data Packet
+ */
+
+'use strict';
+
+import util from '../util.js';
+import crypto from '../crypto';
+import enums from '../enums.js';
+
+const IV_LEN = crypto.gcm.ivLength;
+
+/**
+ * @constructor
+ */
+export default function SymEncryptedAEADProtected() {
+  this.tag = enums.packet.symEncryptedAEADProtected;
+  this.iv = null;
+  this.encrypted = null;
+  /** Decrypted packets contained within.
+   * @type {module:packet/packetlist} */
+  this.packets =  null;
+}
+
+SymEncryptedAEADProtected.prototype.read = function (bytes) {
+  this.iv = bytes.subarray(0, IV_LEN);
+  this.encrypted = bytes.subarray(IV_LEN, bytes.length);
+};
+
+SymEncryptedAEADProtected.prototype.write = function () {
+  return util.concatUint8Array([this.iv, this.encrypted]);
+};
+
+SymEncryptedAEADProtected.prototype.decrypt = function (sessionKeyAlgorithm, key) {
+  return crypto.gcm.decrypt(sessionKeyAlgorithm, this.encrypted, key, this.iv).then(decrypted => {
+    this.packets.read(decrypted);
+  });
+};
+
+SymEncryptedAEADProtected.prototype.encrypt = function (sessionKeyAlgorithm, key) {
+  var data = this.packets.write();
+  this.iv = crypto.random.getRandomValues(new Uint8Array(IV_LEN));
+
+  return crypto.gcm.encrypt(sessionKeyAlgorithm, data, key, this.iv).then(encrypted => {
+    this.encrypted = encrypted;
+  });
+};