Multi-device part 1: make primary account generate and send authorisation to secondary

app/sql.js

@@ -72,6 +72,8 @@ module.exports = {
   removeContactSignedPreKeyByIdentityKey,
   removeAllContactSignedPreKeys,
 
+  createOrUpdatePairingAuthorisation,
+
   createOrUpdateItem,
   getItemById,
   getAllItems,
@@ -737,6 +739,28 @@ async function updateToSchemaVersion11(currentVersion, instance) {
   console.log('updateToSchemaVersion11: success!');
 }
 
+async function updateToSchemaVersion12(currentVersion, instance) {
+  if (currentVersion >= 12) {
+    return;
+  }
+  console.log('updateToSchemaVersion12: starting...');
+  await instance.run('BEGIN TRANSACTION;');
+
+  await instance.run(
+    `CREATE TABLE pairingAuthorisations(
+      id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
+      issuerPubKey VARCHAR(255),
+      secondaryDevicePubKey VARCHAR(255),
+      signature VARCHAR(255),
+      json TEXT
+    );`
+  );
+
+  await instance.run('PRAGMA schema_version = 12;');
+  await instance.run('COMMIT TRANSACTION;');
+  console.log('updateToSchemaVersion12: success!');
+}
+
 const SCHEMA_VERSIONS = [
   updateToSchemaVersion1,
   updateToSchemaVersion2,
@@ -749,6 +773,7 @@ const SCHEMA_VERSIONS = [
   updateToSchemaVersion9,
   updateToSchemaVersion10,
   updateToSchemaVersion11,
+  updateToSchemaVersion12,
 ];
 
 async function updateSchema(instance) {
@@ -1135,6 +1160,54 @@ async function removeAllSignedPreKeys() {
   return removeAllFromTable(SIGNED_PRE_KEYS_TABLE);
 }
 
+const PAIRING_AUTHORISATIONS_TABLE = 'pairingAuthorisations';
+async function getPairingAuthorisation(issuerPubKey, secondaryDevicePubKey) {
+  const row = await db.get(
+    `SELECT * FROM ${PAIRING_AUTHORISATIONS_TABLE} WHERE
+      issuerPubKey = $issuerPubKey AND secondaryDevicePubKey = $secondaryDevicePubKey
+      LIMIT 1;`,
+    {
+      $issuerPubKey: issuerPubKey,
+      $secondaryDevicePubKey: secondaryDevicePubKey,
+    }
+  );
+
+  if (!row) {
+    return null;
+  }
+
+  return jsonToObject(row.json);
+}
+async function createOrUpdatePairingAuthorisation(data) {
+  const { issuerPubKey, secondaryDevicePubKey, signature } = data;
+
+  const existing = await getPairingAuthorisation(issuerPubKey, secondaryDevicePubKey);
+  // prevent adding duplicate entries
+  if (existing) {
+    return;
+  }
+
+  await db.run(
+    `INSERT INTO ${PAIRING_AUTHORISATIONS_TABLE} (
+      issuerPubKey,
+      secondaryDevicePubKey,
+      signature,
+      json
+    ) values (
+      $issuerPubKey,
+      $secondaryDevicePubKey,
+      $signature,
+      $json
+    )`,
+    {
+      $issuerPubKey: issuerPubKey,
+      $secondaryDevicePubKey: secondaryDevicePubKey,
+      $signature: signature,
+      $json: objectToJSON(data),
+    }
+  );
+}
+
 const ITEMS_TABLE = 'items';
 async function createOrUpdateItem(data) {
   return createOrUpdate(ITEMS_TABLE, data);

js/modules/data.js

@@ -12,6 +12,7 @@ const {
   merge,
   set,
   omit,
+  isArrayBuffer,
 } = require('lodash');
 
 const { base64ToArrayBuffer, arrayBufferToBase64 } = require('./crypto');
@@ -88,6 +89,8 @@ module.exports = {
   removeContactSignedPreKeyByIdentityKey,
   removeAllContactSignedPreKeys,
 
+  createOrUpdatePairingAuthorisation,
+
   createOrUpdateItem,
   getItemById,
   getAllItems,
@@ -570,6 +573,23 @@ async function removeAllContactSignedPreKeys() {
   await channels.removeAllContactSignedPreKeys();
 }
 
+async function createOrUpdatePairingAuthorisation(data) {
+  let sig;
+  if (isArrayBuffer(data.signature)) {
+    sig = arrayBufferToBase64(data.signature);
+  } else if (typeof signature === 'string') {
+    sig = data.signature;
+  } else {
+    throw new Error(
+      'Invalid signature provided in createOrUpdatePairingAuthorisation. Needs to be either ArrayBuffer or string.'
+    );
+  }
+  return channels.createOrUpdatePairingAuthorisation({
+    ...data,
+    signature: sig,
+  });
+}
+
 // Items
 
 const ITEM_KEYS = {

libloki/api.js

@@ -63,9 +63,37 @@
     await outgoingMessage.sendToNumber(pubKey);
   }
 
+  async function sendPairingAuthorisation(secondaryDevicePubKey, signature) {
+    const pairingAuthorisation = new textsecure.protobuf.PairingAuthorisationMessage(
+      {
+        signature,
+        primaryDevicePubKey: textsecure.storage.user.getNumber(),
+        secondaryDevicePubKey,
+        type:
+          textsecure.protobuf.PairingAuthorisationMessage.Type.PAIRING_REQUEST,
+      }
+    );
+    const content = new textsecure.protobuf.Content({
+      pairingAuthorisation,
+    });
+    const options = {};
+    // Send a empty message with information about how to contact us directly
+    const outgoingMessage = new textsecure.OutgoingMessage(
+      null, // server
+      Date.now(), // timestamp,
+      [secondaryDevicePubKey], // numbers
+      content, // message
+      true, // silent
+      () => null, // callback
+      options
+    );
+    await outgoingMessage.sendToNumber(secondaryDevicePubKey);
+  }
+
   window.libloki.api = {
     sendBackgroundMessage,
     sendOnlineBroadcastMessage,
     broadcastOnlineStatus,
+    sendPairingAuthorisation,
   };
 })();

libloki/crypto.js

@@ -158,6 +158,47 @@
     }
   }
 
+  async function generateSignatureForPairing(secondaryPubKey, type) {
+    const pubKeyArrayBuffer = StringView.hexToArrayBuffer(secondaryPubKey);
+    // Make sure the signature includes the pairing action (pairing or unpairing)
+    const len = pubKeyArrayBuffer.byteLength;
+    const data = new Uint8Array(len + 1);
+    data.set(new Uint8Array(pubKeyArrayBuffer), 0);
+    data[len] = type;
+
+    const myKeyPair = await textsecure.storage.protocol.getIdentityKeyPair();
+    const signature = await libsignal.Curve.async.calculateSignature(
+      myKeyPair.privKey,
+      data.buffer
+    );
+    return new Uint8Array(signature);
+  }
+
+  async function verifyPairingAuthorisation(
+    issuerPubKey,
+    secondaryPubKey,
+    signature,
+    type
+  ) {
+    const myKeyPair = await textsecure.storage.protocol.getIdentityKeyPair();
+    if (StringView.arrayBufferToHex(myKeyPair.pubKey) !== secondaryPubKey) {
+      throw new Error(
+        'Invalid pairing authorisation: we are not the recipient of the authorisation!'
+      );
+    }
+    const len = myKeyPair.pubKey.byteLength;
+    const data = new Uint8Array(len + 1);
+    data.set(new Uint8Array(myKeyPair.pubKey), 0);
+    data[len] = type;
+    const issuerPubKeyArrayBuffer = StringView.hexToArrayBuffer(issuerPubKey);
+    // Throws for invalid signature
+    await libsignal.Curve.async.verifySignature(
+      issuerPubKeyArrayBuffer,
+      data.buffer,
+      signature
+    );
+  }
+
   const snodeCipher = new LokiSnodeChannel();
 
   window.libloki.crypto = {
@@ -166,6 +207,8 @@
     FallBackSessionCipher,
     FallBackDecryptionError,
     snodeCipher,
+    generateSignatureForPairing,
+    verifyPairingAuthorisation,
     // for testing
     _LokiSnodeChannel: LokiSnodeChannel,
     _decodeSnodeAddressToPubKey: decodeSnodeAddressToPubKey,

libloki/storage.js

@@ -113,11 +113,24 @@
     }
   }
 
+  async function savePairingAuthorisation(
+    issuerPubKey,
+    secondaryDevicePubKey,
+    signature
+  ) {
+    return textsecure.storage.protocol.storePairingAuthorisation(
+      issuerPubKey,
+      secondaryDevicePubKey,
+      signature
+    );
+  }
+
   window.libloki.storage = {
     getPreKeyBundleForContact,
     saveContactPreKeyBundle,
     removeContactPreKeyBundle,
     verifyFriendRequestAcceptPreKey,
+    savePairingAuthorisation,
   };
 
   // Libloki protocol store
@@ -243,4 +256,15 @@
   store.clearContactSignedPreKeysStore = async () => {
     await window.Signal.Data.removeAllContactSignedPreKeys();
   };
+
+  store.storePairingAuthorisation = (
+    issuerPubKey,
+    secondaryDevicePubKey,
+    signature
+  ) =>
+    window.Signal.Data.createOrUpdatePairingAuthorisation({
+      issuerPubKey,
+      secondaryDevicePubKey,
+      signature,
+    });
 })();

libtextsecure/account_manager.js

@@ -2,6 +2,8 @@
   window,
   textsecure,
   libsignal,
+  libloki,
+  Whisper,
   mnemonic,
   btoa,
   Signal,
@@ -553,6 +555,40 @@
 
       this.dispatchEvent(new Event('registration'));
     },
+    async authoriseSecondaryDevice(secondaryDevicePubKey) {
+      if (secondaryDevicePubKey === textsecure.storage.user.getNumber()) {
+        throw new Error(
+          'Cannot register primary device pubkey as secondary device'
+        );
+      }
+
+      // Validate pubKey
+      const c = new Whisper.Conversation({
+        id: secondaryDevicePubKey,
+        type: 'private',
+      });
+      const validationError = c.validateNumber();
+      if (validationError) {
+        throw new Error('Invalid secondary device pubkey provided');
+      }
+      // Ensure there is a conversation existing
+      try {
+        await ConversationController.getOrCreateAndWait(
+          secondaryDevicePubKey,
+          'private'
+        );
+      } catch (e) {
+        window.log.error(e);
+      }
+      const signature = await libloki.crypto.generateSignatureForPairing(
+        secondaryDevicePubKey,
+        textsecure.protobuf.PairingAuthorisationMessage.Type.PAIRING_REQUEST
+      );
+      await libloki.api.sendPairingAuthorisation(
+        secondaryDevicePubKey,
+        signature
+      );
+    },
   });
   textsecure.AccountManager = AccountManager;
 })();

libtextsecure/message_receiver.js

@@ -1022,6 +1022,49 @@ MessageReceiver.prototype.extend({
     }
     return this.removeFromCache(envelope);
   },
+  async handlePairingAuthorisationMessage(envelope, pairingAuthorisation) {
+    const {
+      type,
+      primaryDevicePubKey,
+      secondaryDevicePubKey,
+      signature,
+    } = pairingAuthorisation;
+    const sigArrayBuffer = dcodeIO.ByteBuffer.wrap(signature).toArrayBuffer();
+    if (
+      type ===
+      textsecure.protobuf.PairingAuthorisationMessage.Type.PAIRING_REQUEST
+    ) {
+      window.log.info(
+        `Received pairing authorisation from ${primaryDevicePubKey}`
+      );
+      let validAuthorisation = false;
+      try {
+        await libloki.crypto.verifyPairingAuthorisation(
+          primaryDevicePubKey,
+          secondaryDevicePubKey,
+          sigArrayBuffer,
+          type
+        );
+        validAuthorisation = true;
+      } catch (e) {
+        window.log.error(e);
+      }
+      if (validAuthorisation) {
+        await libloki.storage.savePairingAuthorisation(
+          primaryDevicePubKey,
+          secondaryDevicePubKey,
+          sigArrayBuffer
+        );
+      } else {
+        window.log.warn(
+          'Could not verify pairing authorisation signature. Ignoring message.'
+        );
+      }
+    } else {
+      window.log.warn('Unimplemented pairing authorisation message type');
+    }
+    return this.removeFromCache(envelope);
+  },
   handleDataMessage(envelope, msg) {
     if (!envelope.isP2p) {
       const timestamp = envelope.timestamp.toNumber();
@@ -1133,6 +1176,12 @@ MessageReceiver.prototype.extend({
         content.lokiAddressMessage
       );
     }
+    if (content.pairingAuthorisation) {
+      return this.handlePairingAuthorisationMessage(
+        envelope,
+        content.pairingAuthorisation
+      );
+    }
     if (content.syncMessage) {
       return this.handleSyncMessage(envelope, content.syncMessage);
     }

libtextsecure/outgoing_message.js

@@ -302,12 +302,13 @@ OutgoingMessage.prototype = {
         // Check if we need to attach the preKeys
         let sessionCipher;
         const isFriendRequest = this.messageType === 'friend-request';
+        this.fallBackEncryption = this.fallBackEncryption || isFriendRequest;
         const flags = this.message.dataMessage
           ? this.message.dataMessage.get_flags()
           : null;
         const isEndSession =
           flags === textsecure.protobuf.DataMessage.Flags.END_SESSION;
-        if (isFriendRequest || isEndSession) {
+        if (this.fallBackEncryption || isEndSession) {
           // Encrypt them with the fallback
           const pkb = await libloki.storage.getPreKeyBundleForContact(number);
           const preKeyBundleMessage = new textsecure.protobuf.PreKeyBundleMessage(
@@ -316,7 +317,7 @@ OutgoingMessage.prototype = {
           this.message.preKeyBundleMessage = preKeyBundleMessage;
           window.log.info('attaching prekeys to outgoing message');
         }
-        if (isFriendRequest) {
+        if (this.fallBackEncryption) {
           sessionCipher = fallBackCipher;
         } else {
           sessionCipher = new libsignal.SessionCipher(

protos/SignalService.proto

@@ -36,6 +36,7 @@ message Content {
   optional TypingMessage  typingMessage  = 6;
   optional PreKeyBundleMessage preKeyBundleMessage = 101;
   optional LokiAddressMessage lokiAddressMessage = 102;
+  optional PairingAuthorisationMessage pairingAuthorisation = 103;
 }
 
 message LokiAddressMessage {
@@ -48,6 +49,17 @@ message LokiAddressMessage {
   optional Type   type          = 3;
 }
 
+message PairingAuthorisationMessage {
+  enum Type {
+    PAIRING_REQUEST = 1;
+    UNPAIRING_REQUEST = 2;
+  }
+  optional string primaryDevicePubKey   = 1;
+  optional string secondaryDevicePubKey = 2;
+  optional bytes  signature             = 3;
+  optional Type   type                  = 4;
+}
+
 message PreKeyBundleMessage {
   optional bytes identityKey      = 1;
   optional uint32 deviceId        = 2;