pjs/services/sync/modules/jpakeclient.js

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JavaScript

/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Firefox Sync.
*
* The Initial Developer of the Original Code is
* Mozilla Foundation.
* Portions created by the Initial Developer are Copyright (C) 2010
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Philipp von Weitershausen <philipp@weitershausen.de>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
const Cc = Components.classes;
const Ci = Components.interfaces;
const Cr = Components.results;
const Cu = Components.utils;
Cu.import("resource://services-sync/log4moz.js");
Cu.import("resource://services-sync/resource.js");
Cu.import("resource://services-sync/constants.js");
Cu.import("resource://services-sync/util.js");
const EXPORTED_SYMBOLS = ["JPAKEClient"];
const JPAKE_SIGNERID_SENDER = "sender";
const JPAKE_SIGNERID_RECEIVER = "receiver";
const JPAKE_LENGTH_SECRET = 8;
const JPAKE_LENGTH_CLIENTID = 256;
const JPAKE_VERIFY_VALUE = "0123456789ABCDEF";
/*
* Client to exchange encrypted data using the J-PAKE algorithm.
* The exchange between two clients of this type looks like this:
*
*
* Client A Server Client B
* ==================================================================
* |
* retrieve channel <---------------|
* generate random secret |
* show PIN = secret + channel | ask user for PIN
* upload A's message 1 ----------->|
* |--------> retrieve A's message 1
* |<---------- upload B's message 1
* retrieve B's message 1 <---------|
* upload A's message 2 ----------->|
* |--------> retrieve A's message 2
* | compute key
* |<---------- upload B's message 2
* retrieve B's message 2 <---------|
* compute key |
* upload sha256d(key) ------------>|
* |---------> retrieve sha256d(key)
* | verify against own key
* | encrypt data
* |<------------------- upload data
* retrieve data <------------------|
* verify HMAC |
* decrypt data |
*
*
* Create a client object like so:
*
* let client = new JPAKEClient(observer);
*
* The 'observer' object must implement the following methods:
*
* displayPIN(pin) -- Display the PIN to the user, only called on the client
* that didn't provide the PIN.
*
* onComplete(data) -- Called after transfer has been completed. On
* the sending side this is called with no parameter and as soon as the
* data has been uploaded, which this doesn't mean the receiving side
* has actually retrieved them yet.
*
* onAbort(error) -- Called whenever an error is encountered. All errors lead
* to an abort and the process has to be started again on both sides.
*
* To start the data transfer on the receiving side, call
*
* client.receiveNoPIN();
*
* This will allocate a new channel on the server, generate a PIN, have it
* displayed and then do the transfer once the protocol has been completed
* with the sending side.
*
* To initiate the transfer from the sending side, call
*
* client.sendWithPIN(pin, data)
*
* To abort the process, call
*
* client.abort();
*
* Note that after completion or abort, the 'client' instance may not be reused.
* You will have to create a new one in case you'd like to restart the process.
*/
function JPAKEClient(observer) {
this.observer = observer;
this._log = Log4Moz.repository.getLogger("Service.JPAKEClient");
this._log.level = Log4Moz.Level[Svc.Prefs.get(
"log.logger.service.jpakeclient", "Debug")];
this._serverUrl = Svc.Prefs.get("jpake.serverURL");
this._pollInterval = Svc.Prefs.get("jpake.pollInterval");
this._maxTries = Svc.Prefs.get("jpake.maxTries");
if (this._serverUrl.slice(-1) != "/")
this._serverUrl += "/";
this._jpake = Cc["@mozilla.org/services-crypto/sync-jpake;1"]
.createInstance(Ci.nsISyncJPAKE);
this._auth = new NoOpAuthenticator();
this._setClientID();
}
JPAKEClient.prototype = {
_chain: Utils.asyncChain,
/*
* Public API
*/
receiveNoPIN: function receiveNoPIN() {
this._my_signerid = JPAKE_SIGNERID_RECEIVER;
this._their_signerid = JPAKE_SIGNERID_SENDER;
this._secret = this._createSecret();
// Allow a large number of tries first while we wait for the PIN
// to be entered on the other device.
this._maxTries = Svc.Prefs.get("jpake.firstMsgMaxTries");
this._chain(this._getChannel,
this._computeStepOne,
this._putStep,
this._getStep,
function(callback) {
// Now we can switch back to the smaller timeout.
this._maxTries = Svc.Prefs.get("jpake.maxTries");
callback();
},
this._computeStepTwo,
this._putStep,
this._getStep,
this._computeFinal,
this._computeKeyVerification,
this._putStep,
this._getStep,
this._decryptData,
this._complete)();
},
sendWithPIN: function sendWithPIN(pin, obj) {
this._my_signerid = JPAKE_SIGNERID_SENDER;
this._their_signerid = JPAKE_SIGNERID_RECEIVER;
this._channel = pin.slice(JPAKE_LENGTH_SECRET);
this._channelUrl = this._serverUrl + this._channel;
this._secret = pin.slice(0, JPAKE_LENGTH_SECRET);
this._data = JSON.stringify(obj);
this._chain(this._computeStepOne,
this._getStep,
this._putStep,
this._computeStepTwo,
this._getStep,
this._putStep,
this._computeFinal,
this._getStep,
this._encryptData,
this._putStep,
this._complete)();
},
abort: function abort(error) {
this._log.debug("Aborting...");
this._finished = true;
let self = this;
if (error == JPAKE_ERROR_CHANNEL
|| error == JPAKE_ERROR_NETWORK
|| error == JPAKE_ERROR_NODATA) {
Utils.delay(function() { this.observer.onAbort(error); }, 0,
this, "_timer_onAbort");
} else {
this._reportFailure(error, function() { self.observer.onAbort(error); });
}
},
/*
* Utilities
*/
_setClientID: function _setClientID() {
let rng = Cc["@mozilla.org/security/random-generator;1"]
.createInstance(Ci.nsIRandomGenerator);
let bytes = rng.generateRandomBytes(JPAKE_LENGTH_CLIENTID / 2);
this._clientID = [("0" + byte.toString(16)).slice(-2)
for each (byte in bytes)].join("");
},
_createSecret: function _createSecret() {
// 0-9a-z without 1,l,o,0
const key = "23456789abcdefghijkmnpqrstuvwxyz";
let rng = Cc["@mozilla.org/security/random-generator;1"]
.createInstance(Ci.nsIRandomGenerator);
let bytes = rng.generateRandomBytes(JPAKE_LENGTH_SECRET);
return [key[Math.floor(byte * key.length / 256)]
for each (byte in bytes)].join("");
},
/*
* Steps of J-PAKE procedure
*/
_getChannel: function _getChannel(callback) {
this._log.trace("Requesting channel.");
let resource = new AsyncResource(this._serverUrl + "new_channel");
resource.authenticator = this._auth;
resource.setHeader("X-KeyExchange-Id", this._clientID);
resource.get(Utils.bind2(this, function handleChannel(error, response) {
if (this._finished)
return;
if (error) {
this._log.error("Error acquiring channel ID. " + error);
this.abort(JPAKE_ERROR_CHANNEL);
return;
}
if (response.status != 200) {
this._log.error("Error acquiring channel ID. Server responded with HTTP "
+ response.status);
this.abort(JPAKE_ERROR_CHANNEL);
return;
}
let channel;
try {
this._channel = response.obj;
} catch (ex) {
this._log.error("Server responded with invalid JSON.");
this.abort(JPAKE_ERROR_CHANNEL);
return;
}
this._log.debug("Using channel " + this._channel);
this._channelUrl = this._serverUrl + this._channel;
// Don't block on UI code.
let pin = this._secret + this._channel;
Utils.delay(function() { this.observer.displayPIN(pin); }, 0,
this, "_timer_displayPIN");
callback();
}));
},
// Generic handler for uploading data.
_putStep: function _putStep(callback) {
this._log.trace("Uploading message " + this._outgoing.type);
let resource = new AsyncResource(this._channelUrl);
resource.authenticator = this._auth;
resource.setHeader("X-KeyExchange-Id", this._clientID);
resource.put(this._outgoing, Utils.bind2(this, function (error, response) {
if (this._finished)
return;
if (error) {
this._log.error("Error uploading data. " + error);
this.abort(JPAKE_ERROR_NETWORK);
return;
}
if (response.status != 200) {
this._log.error("Could not upload data. Server responded with HTTP "
+ response.status);
this.abort(JPAKE_ERROR_SERVER);
return;
}
// There's no point in returning early here since the next step will
// always be a GET so let's pause for twice the poll interval.
this._etag = response.headers["etag"];
Utils.delay(function () { callback(); }, this._pollInterval * 2, this,
"_pollTimer");
}));
},
// Generic handler for polling for and retrieving data.
_pollTries: 0,
_getStep: function _getStep(callback) {
this._log.trace("Retrieving next message.");
let resource = new AsyncResource(this._channelUrl);
resource.authenticator = this._auth;
resource.setHeader("X-KeyExchange-Id", this._clientID);
if (this._etag)
resource.setHeader("If-None-Match", this._etag);
resource.get(Utils.bind2(this, function (error, response) {
if (this._finished)
return;
if (error) {
this._log.error("Error fetching data. " + error);
this.abort(JPAKE_ERROR_NETWORK);
return;
}
if (response.status == 304) {
this._log.trace("Channel hasn't been updated yet. Will try again later.");
if (this._pollTries >= this._maxTries) {
this._log.error("Tried for " + this._pollTries + " times, aborting.");
this.abort(JPAKE_ERROR_TIMEOUT);
return;
}
this._pollTries += 1;
Utils.delay(function() { this._getStep(callback); },
this._pollInterval, this, "_pollTimer");
return;
}
this._pollTries = 0;
if (response.status == 404) {
this._log.error("No data found in the channel.");
this.abort(JPAKE_ERROR_NODATA);
return;
}
if (response.status != 200) {
this._log.error("Could not retrieve data. Server responded with HTTP "
+ response.status);
this.abort(JPAKE_ERROR_SERVER);
return;
}
try {
this._incoming = response.obj;
} catch (ex) {
this._log.error("Server responded with invalid JSON.");
this.abort(JPAKE_ERROR_INVALID);
return;
}
this._log.trace("Fetched message " + this._incoming.type);
callback();
}));
},
_reportFailure: function _reportFailure(reason, callback) {
this._log.debug("Reporting failure to server.");
let resource = new AsyncResource(this._serverUrl + "report");
resource.authenticator = this._auth;
resource.setHeader("X-KeyExchange-Id", this._clientID);
resource.setHeader("X-KeyExchange-Cid", this._channel);
resource.setHeader("X-KeyExchange-Log", reason);
resource.post("", Utils.bind2(this, function (error, response) {
if (error)
this._log.warn("Report failed: " + error);
else if (response.status != 200)
this._log.warn("Report failed. Server responded with HTTP "
+ response.status);
// Do not block on errors, we're done or aborted by now anyway.
callback();
}));
},
_computeStepOne: function _computeStepOne(callback) {
this._log.trace("Computing round 1.");
let gx1 = {};
let gv1 = {};
let r1 = {};
let gx2 = {};
let gv2 = {};
let r2 = {};
try {
this._jpake.round1(this._my_signerid, gx1, gv1, r1, gx2, gv2, r2);
} catch (ex) {
this._log.error("JPAKE round 1 threw: " + ex);
this.abort(JPAKE_ERROR_INTERNAL);
return;
}
let one = {gx1: gx1.value,
gx2: gx2.value,
zkp_x1: {gr: gv1.value, b: r1.value, id: this._my_signerid},
zkp_x2: {gr: gv2.value, b: r2.value, id: this._my_signerid}};
this._outgoing = {type: this._my_signerid + "1", payload: one};
this._log.trace("Generated message " + this._outgoing.type);
callback();
},
_computeStepTwo: function _computeStepTwo(callback) {
this._log.trace("Computing round 2.");
if (this._incoming.type != this._their_signerid + "1") {
this._log.error("Invalid round 1 message: "
+ JSON.stringify(this._incoming));
this.abort(JPAKE_ERROR_WRONGMESSAGE);
return;
}
let step1 = this._incoming.payload;
if (!step1 || !step1.zkp_x1 || step1.zkp_x1.id != this._their_signerid
|| !step1.zkp_x2 || step1.zkp_x2.id != this._their_signerid) {
this._log.error("Invalid round 1 payload: " + JSON.stringify(step1));
this.abort(JPAKE_ERROR_WRONGMESSAGE);
return;
}
let A = {};
let gvA = {};
let rA = {};
try {
this._jpake.round2(this._their_signerid, this._secret,
step1.gx1, step1.zkp_x1.gr, step1.zkp_x1.b,
step1.gx2, step1.zkp_x2.gr, step1.zkp_x2.b,
A, gvA, rA);
} catch (ex) {
this._log.error("JPAKE round 2 threw: " + ex);
this.abort(JPAKE_ERROR_INTERNAL);
return;
}
let two = {A: A.value,
zkp_A: {gr: gvA.value, b: rA.value, id: this._my_signerid}};
this._outgoing = {type: this._my_signerid + "2", payload: two};
this._log.trace("Generated message " + this._outgoing.type);
callback();
},
_computeFinal: function _computeFinal(callback) {
if (this._incoming.type != this._their_signerid + "2") {
this._log.error("Invalid round 2 message: "
+ JSON.stringify(this._incoming));
this.abort(JPAKE_ERROR_WRONGMESSAGE);
return;
}
let step2 = this._incoming.payload;
if (!step2 || !step2.zkp_A || step2.zkp_A.id != this._their_signerid) {
this._log.error("Invalid round 2 payload: " + JSON.stringify(step1));
this.abort(JPAKE_ERROR_WRONGMESSAGE);
return;
}
let aes256Key = {};
let hmac256Key = {};
try {
this._jpake.final(step2.A, step2.zkp_A.gr, step2.zkp_A.b, HMAC_INPUT,
aes256Key, hmac256Key);
} catch (ex) {
this._log.error("JPAKE final round threw: " + ex);
this.abort(JPAKE_ERROR_INTERNAL);
return;
}
this._crypto_key = aes256Key.value;
let hmac_key = Utils.makeHMACKey(Utils.safeAtoB(hmac256Key.value));
this._hmac_hasher = Utils.makeHMACHasher(Ci.nsICryptoHMAC.SHA256, hmac_key);
callback();
},
_computeKeyVerification: function _computeKeyVerification(callback) {
this._log.trace("Encrypting key verification value.");
let iv, ciphertext;
try {
iv = Svc.Crypto.generateRandomIV();
ciphertext = Svc.Crypto.encrypt(JPAKE_VERIFY_VALUE,
this._crypto_key, iv);
} catch (ex) {
this._log.error("Failed to encrypt key verification value.");
this.abort(JPAKE_ERROR_INTERNAL);
return;
}
this._outgoing = {type: this._my_signerid + "3",
payload: {ciphertext: ciphertext, IV: iv}};
this._log.trace("Generated message " + this._outgoing.type);
callback();
},
_encryptData: function _encryptData(callback) {
this._log.trace("Verifying their key.");
if (this._incoming.type != this._their_signerid + "3") {
this._log.error("Invalid round 3 data: " +
JSON.stringify(this._incoming));
this.abort(JPAKE_ERROR_WRONGMESSAGE);
return;
}
let step3 = this._incoming.payload;
try {
ciphertext = Svc.Crypto.encrypt(JPAKE_VERIFY_VALUE,
this._crypto_key, step3.IV);
if (ciphertext != step3.ciphertext)
throw "Key mismatch!";
} catch (ex) {
this._log.error("Keys don't match!");
this.abort(JPAKE_ERROR_KEYMISMATCH);
return;
}
this._log.trace("Encrypting data.");
let iv, ciphertext, hmac;
try {
iv = Svc.Crypto.generateRandomIV();
ciphertext = Svc.Crypto.encrypt(this._data, this._crypto_key, iv);
hmac = Utils.bytesAsHex(Utils.digestUTF8(ciphertext, this._hmac_hasher));
} catch (ex) {
this._log.error("Failed to encrypt data.");
this.abort(JPAKE_ERROR_INTERNAL);
return;
}
this._outgoing = {type: this._my_signerid + "3",
payload: {ciphertext: ciphertext, IV: iv, hmac: hmac}};
this._log.trace("Generated message " + this._outgoing.type);
callback();
},
_decryptData: function _decryptData(callback) {
this._log.trace("Verifying their key.");
if (this._incoming.type != this._their_signerid + "3") {
this._log.error("Invalid round 3 data: "
+ JSON.stringify(this._incoming));
this.abort(JPAKE_ERROR_WRONGMESSAGE);
return;
}
let step3 = this._incoming.payload;
try {
let hmac = Utils.bytesAsHex(
Utils.digestUTF8(step3.ciphertext, this._hmac_hasher));
if (hmac != step3.hmac)
throw "HMAC validation failed!";
} catch (ex) {
this._log.error("HMAC validation failed.");
this.abort(JPAKE_ERROR_KEYMISMATCH);
return;
}
this._log.trace("Decrypting data.");
let cleartext;
try {
cleartext = Svc.Crypto.decrypt(step3.ciphertext, this._crypto_key,
step3.IV);
} catch (ex) {
this._log.error("Failed to decrypt data.");
this.abort(JPAKE_ERROR_INTERNAL);
return;
}
try {
this._newData = JSON.parse(cleartext);
} catch (ex) {
this._log.error("Invalid data data: " + JSON.stringify(cleartext));
this.abort(JPAKE_ERROR_INVALID);
return;
}
this._log.trace("Decrypted data.");
callback();
},
_complete: function _complete() {
this._log.debug("Exchange completed.");
this._finished = true;
Utils.delay(function () { this.observer.onComplete(this._newData); },
0, this, "_timer_onComplete");
}
};