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gecko-dev/services/sync/modules/jpakeclient.js

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JavaScript
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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
this.EXPORTED_SYMBOLS = ["JPAKEClient", "SendCredentialsController"];
const {classes: Cc, interfaces: Ci, results: Cr, utils: Cu} = Components;
Cu.import("resource://services-common/log4moz.js");
Cu.import("resource://services-common/rest.js");
Cu.import("resource://services-sync/constants.js");
Cu.import("resource://services-sync/util.js");
const REQUEST_TIMEOUT = 60; // 1 minute
const KEYEXCHANGE_VERSION = 3;
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:
*
*
* Mobile Server Desktop
* ===================================================================
* |
* retrieve channel <---------------|
* generate random secret |
* show PIN = secret + channel | ask user for PIN
* upload Mobile's message 1 ------>|
* |----> retrieve Mobile's message 1
* |<----- upload Desktop's message 1
* retrieve Desktop's message 1 <---|
* upload Mobile's message 2 ------>|
* |----> retrieve Mobile's message 2
* | compute key
* |<----- upload Desktop's message 2
* retrieve Desktop's message 2 <---|
* compute key |
* encrypt known value ------------>|
* |-------> retrieve encrypted value
* | verify against local known value
*
* At this point Desktop knows whether the PIN was entered correctly.
* If it wasn't, Desktop deletes the session. If it was, the account
* setup can proceed. If Desktop doesn't yet have an account set up,
* it will keep the channel open and let the user connect to or
* create an account.
*
* | encrypt credentials
* |<------------- upload credentials
* retrieve credentials <-----------|
* verify HMAC |
* decrypt credentials |
* delete session ----------------->|
* start syncing |
*
*
* Create a client object like so:
*
* let client = new JPAKEClient(controller);
*
* The 'controller' object must implement the following methods:
*
* displayPIN(pin) -- Called when a PIN has been generated and is ready to
* be displayed to the user. Only called on the client where the pairing
* was initiated with 'receiveNoPIN()'.
*
* onPairingStart() -- Called when the pairing has started and messages are
* being sent back and forth over the channel. Only called on the client
* where the pairing was initiated with 'receiveNoPIN()'.
*
* onPaired() -- Called when the device pairing has been established and
* we're ready to send the credentials over. To do that, the controller
* must call 'sendAndComplete()' while the channel is active.
*
* 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. This does not 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.pairWithPIN(pin, true);
*
* Once the pairing has been established, the controller's 'onPaired()' method
* will be called. To then transmit the data, call
*
* client.sendAndComplete(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.
*/
this.JPAKEClient = function JPAKEClient(controller) {
this.controller = controller;
this._log = Log4Moz.repository.getLogger("Sync.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._setClientID();
}
JPAKEClient.prototype = {
_chain: Async.chain,
/*
* Public API
*/
/**
* Initiate pairing and receive data without providing a PIN. The PIN will
* be generated and passed on to the controller to be displayed to the user.
*
* This is typically called on mobile devices where typing is tedious.
*/
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) {
// We fetched the first response from the other client.
// Notify controller of the pairing starting.
Utils.nextTick(this.controller.onPairingStart,
this.controller);
// 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,
function(callback) {
// Allow longer time-out for the last message.
this._maxTries = Svc.Prefs.get("jpake.lastMsgMaxTries");
callback();
},
this._getStep,
this._decryptData,
this._complete)();
},
/**
* Initiate pairing based on the PIN entered by the user.
*
* This is typically called on desktop devices where typing is easier than
* on mobile.
*
* @param pin
* 12 character string (in human-friendly base32) containing the PIN
* entered by the user.
* @param expectDelay
* Flag that indicates that a significant delay between the pairing
* and the sending should be expected. v2 and earlier of the protocol
* did not allow for this and the pairing to a v2 or earlier client
* will be aborted if this flag is 'true'.
*/
pairWithPIN: function pairWithPIN(pin, expectDelay) {
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._chain(this._computeStepOne,
this._getStep,
function (callback) {
// Ensure that the other client can deal with a delay for
// the last message if that's requested by the caller.
if (!expectDelay) {
return callback();
}
if (!this._incoming.version || this._incoming.version < 3) {
return this.abort(JPAKE_ERROR_DELAYUNSUPPORTED);
}
return callback();
},
this._putStep,
this._computeStepTwo,
this._getStep,
this._putStep,
this._computeFinal,
this._getStep,
this._verifyPairing)();
},
/**
* Send data after a successful pairing.
*
* @param obj
* Object containing the data to send. It will be serialized as JSON.
*/
sendAndComplete: function sendAndComplete(obj) {
if (!this._paired || this._finished) {
this._log.error("Can't send data, no active pairing!");
throw "No active pairing!";
}
this._data = JSON.stringify(obj);
this._chain(this._encryptData,
this._putStep,
this._complete)();
},
/**
* Abort the current pairing. The channel on the server will be deleted
* if the abort wasn't due to a network or server error. The controller's
* 'onAbort()' method is notified in all cases.
*
* @param error [optional]
* Error constant indicating the reason for the abort. Defaults to
* user abort.
*/
abort: function abort(error) {
this._log.debug("Aborting...");
this._finished = true;
let self = this;
// Default to "user aborted".
if (!error) {
error = JPAKE_ERROR_USERABORT;
}
if (error == JPAKE_ERROR_CHANNEL ||
error == JPAKE_ERROR_NETWORK ||
error == JPAKE_ERROR_NODATA) {
Utils.nextTick(function() { this.controller.onAbort(error); }, this);
} else {
this._reportFailure(error, function() { self.controller.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("");
},
_newRequest: function _newRequest(uri) {
let request = new RESTRequest(uri);
request.setHeader("X-KeyExchange-Id", this._clientID);
request.timeout = REQUEST_TIMEOUT;
return request;
},
/*
* Steps of J-PAKE procedure
*/
_getChannel: function _getChannel(callback) {
this._log.trace("Requesting channel.");
let request = this._newRequest(this._serverURL + "new_channel");
request.get(Utils.bind2(this, function handleChannel(error) {
if (this._finished) {
return;
}
if (error) {
this._log.error("Error acquiring channel ID. " + error);
this.abort(JPAKE_ERROR_CHANNEL);
return;
}
if (request.response.status != 200) {
this._log.error("Error acquiring channel ID. Server responded with HTTP "
+ request.response.status);
this.abort(JPAKE_ERROR_CHANNEL);
return;
}
try {
this._channel = JSON.parse(request.response.body);
} 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.nextTick(function() { this.controller.displayPIN(pin); }, this);
callback();
}));
},
// Generic handler for uploading data.
_putStep: function _putStep(callback) {
this._log.trace("Uploading message " + this._outgoing.type);
let request = this._newRequest(this._channelURL);
if (this._their_etag) {
request.setHeader("If-Match", this._their_etag);
} else {
request.setHeader("If-None-Match", "*");
}
request.put(this._outgoing, Utils.bind2(this, function (error) {
if (this._finished) {
return;
}
if (error) {
this._log.error("Error uploading data. " + error);
this.abort(JPAKE_ERROR_NETWORK);
return;
}
if (request.response.status != 200) {
this._log.error("Could not upload data. Server responded with HTTP "
+ request.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._my_etag = request.response.headers["etag"];
Utils.namedTimer(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 request = this._newRequest(this._channelURL);
if (this._my_etag) {
request.setHeader("If-None-Match", this._my_etag);
}
request.get(Utils.bind2(this, function (error) {
if (this._finished) {
return;
}
if (error) {
this._log.error("Error fetching data. " + error);
this.abort(JPAKE_ERROR_NETWORK);
return;
}
if (request.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.namedTimer(function() { this._getStep(callback); },
this._pollInterval, this, "_pollTimer");
return;
}
this._pollTries = 0;
if (request.response.status == 404) {
this._log.error("No data found in the channel.");
this.abort(JPAKE_ERROR_NODATA);
return;
}
if (request.response.status != 200) {
this._log.error("Could not retrieve data. Server responded with HTTP "
+ request.response.status);
this.abort(JPAKE_ERROR_SERVER);
return;
}
this._their_etag = request.response.headers["etag"];
if (!this._their_etag) {
this._log.error("Server did not supply ETag for message: "
+ request.response.body);
this.abort(JPAKE_ERROR_SERVER);
return;
}
try {
this._incoming = JSON.parse(request.response.body);
} 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 request = this._newRequest(this._serverURL + "report");
request.setHeader("X-KeyExchange-Cid", this._channel);
request.setHeader("X-KeyExchange-Log", reason);
request.post("", Utils.bind2(this, function (error) {
if (error) {
this._log.warn("Report failed: " + error);
} else if (request.response.status != 200) {
this._log.warn("Report failed. Server responded with HTTP "
+ request.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",
version: KEYEXCHANGE_VERSION,
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",
version: KEYEXCHANGE_VERSION,
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",
version: KEYEXCHANGE_VERSION,
payload: {ciphertext: ciphertext, IV: iv}};
this._log.trace("Generated message " + this._outgoing.type);
callback();
},
_verifyPairing: function _verifyPairing(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;
let ciphertext;
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.debug("Verified pairing!");
this._paired = true;
Utils.nextTick(function () { this.controller.onPaired(); }, this);
callback();
},
_encryptData: function _encryptData(callback) {
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",
version: KEYEXCHANGE_VERSION,
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.nextTick(function () { this.controller.onComplete(this._newData); },
this);
}
};
/**
* Send credentials over an active J-PAKE channel.
*
* This object is designed to take over as the JPAKEClient controller,
* presumably replacing one that is UI-based which would either cause
* DOM objects to leak or the JPAKEClient to be GC'ed when the DOM
* context disappears. This object stays alive for the duration of the
* transfer by being strong-ref'ed as an nsIObserver.
*
* Credentials are sent after the first sync has been completed
* (successfully or not.)
*
* Usage:
*
* jpakeclient.controller = new SendCredentialsController(jpakeclient,
* service);
*
*/
this.SendCredentialsController =
function SendCredentialsController(jpakeclient, service) {
this._log = Log4Moz.repository.getLogger("Sync.SendCredentialsController");
this._log.level = Log4Moz.Level[Svc.Prefs.get("log.logger.service.main")];
this._log.trace("Loading.");
this.jpakeclient = jpakeclient;
this.service = service;
// Register ourselves as observers the first Sync finishing (either
// successfully or unsuccessfully, we don't care) or for removing
// this device's sync configuration, in case that happens while we
// haven't finished the first sync yet.
Services.obs.addObserver(this, "weave:service:sync:finish", false);
Services.obs.addObserver(this, "weave:service:sync:error", false);
Services.obs.addObserver(this, "weave:service:start-over", false);
}
SendCredentialsController.prototype = {
unload: function unload() {
this._log.trace("Unloading.");
try {
Services.obs.removeObserver(this, "weave:service:sync:finish");
Services.obs.removeObserver(this, "weave:service:sync:error");
Services.obs.removeObserver(this, "weave:service:start-over");
} catch (ex) {
// Ignore.
}
},
observe: function observe(subject, topic, data) {
switch (topic) {
case "weave:service:sync:finish":
case "weave:service:sync:error":
Utils.nextTick(this.sendCredentials, this);
break;
case "weave:service:start-over":
// This will call onAbort which will call unload().
this.jpakeclient.abort();
break;
}
},
sendCredentials: function sendCredentials() {
this._log.trace("Sending credentials.");
let credentials = {account: this.service.identity.account,
password: this.service.identity.basicPassword,
synckey: this.service.identity.syncKey,
serverURL: this.service.serverURL};
this.jpakeclient.sendAndComplete(credentials);
},
// JPAKEClient controller API
onComplete: function onComplete() {
this._log.debug("Exchange was completed successfully!");
this.unload();
// Schedule a Sync for soonish to fetch the data uploaded by the
// device with which we just paired.
this.service.scheduler.scheduleNextSync(this.service.scheduler.activeInterval);
},
onAbort: function onAbort(error) {
// It doesn't really matter why we aborted, but the channel is closed
// for sure, so we won't be able to do anything with it.
this._log.debug("Exchange was aborted with error: " + error);
this.unload();
},
// Irrelevant methods for this controller:
displayPIN: function displayPIN() {},
onPairingStart: function onPairingStart() {},
onPaired: function onPaired() {},
};
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