Wallet won't show request details

[Svechnikov]

Hello!

I'm developing a dapp Flutter application for V1 WalletConnect protocol and having difficulties with pairing with wallets.

I couldn't find a sample app on Flutter (I only found apps that act like wallets, receiving requests), so I decided to write my own code, using the specifications and WalletConnectKotlinV2 sample (I'm aware it is for version 2, but still it helped me).

Basically, I'm doing everything described in the specification diagram:

1. Generate a key and a topic
2. Create a WaletConnect format URI with those key and topic
3. Open a socket to the bridge server and subscribe for topic messages
4. Send wc_sessionRequest to the socket
5. Open the WaletConnect format URI in the MetaMask wallet

I expect MetaMask to show request details, but it just opens the app and nothing happens. Also, I receive no messages from the socket.

Here's an example of the actions I do in the chronological order:

Sending the topic subscription request to the socket:

{
  "topic": "85391ed942cd06511fda5251c4d648873678eb6acace41a0a56cb1d5aa114dca",
  "type": "sub",
  "payload": ""
}

Sending the peerId subscription request to the socket (not sure if it's needed, but I saw it in some sample):

{
  "topic": "9ca7ec3b-55d9-4aa3-a354-65e005404c28",
  "type": "sub",
  "payload": ""
}

Sending the session request to the socket:

{
  "topic": "85391ed942cd06511fda5251c4d648873678eb6acace41a0a56cb1d5aa114dca",
  "type": "pub",
  "payload": "{\"data\":\"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\",\"hmac\":\"3bcda663eb3f9219c26d0de0e5997aaf112e899a655ac11754d4bd130e3b4764\",\"iv\":\"e0a9555894282c91b44b168326199d24\"}"
}

Opening the uri in MetaMask (this is an android shell command):

adb shell am start -a android.intent.action.VIEW -d "wc:85391ed942cd06511fda5251c4d648873678eb6acace41a0a56cb1d5aa114dca@1?bridge=https%3A%2F%2Fj.bridge.walletconnect.org&key=2c2841852c7a42fb6a3fe821bae5fd8bcfbaedb64a064a06170860fe5ff570cb"

I think the reason might be in encrypting (or signing).

Can you please help me figure this out? Thanks in advance!

And here's the code:

import 'dart:convert';
import 'dart:math';
import 'dart:typed_data';

import 'package:crypto/crypto.dart';
import 'package:encrypt/encrypt.dart';
import 'package:hex/hex.dart';
import 'package:uuid/uuid.dart';
import 'package:web_socket_channel/web_socket_channel.dart';

List<int> generateRandomKey() {
  final random = Random();
  return List.generate(32, (i) => random.nextInt(256));
}

void main() async {
  const walletConnectProjectId = "my-project-id";
  const bridgeHost = "j.bridge.walletconnect.org";
  const bridge = "https://$bridgeHost";

  final key = generateRandomKey();
  final topic = HEX.encode(generateRandomKey());

  // this uri is used like the following:
  // adb shell am start -a android.intent.action.VIEW -d URI
  final uri = "wc:$topic@1?bridge=${Uri.encodeComponent(bridge)}&key=${HEX.encode(key)}";
  print(uri);

  const jsonEncoder = JsonEncoder();

  final peerId = const Uuid().v4();
  // Session request, will be encrypted
  final requestString = jsonEncoder.convert({
    "id": 1,
    "jsonrpc": "2.0",
    "method": "wc_sessionRequest",
    "params": [
      {
        "peerId": peerId,
        "peerMeta": {
          "name": "Kotlin Wallet",
          "description": "Wallet description",
          "url": "example.wallet",
          "icons": ["https://gblobscdn.gitbook.com/spaces%2F-LJJeCjcLrr53DcT1Ml7%2Favatar.png?alt=media"]
        },
        "chainId": null,
      }
    ]
  });
  // AES-256-CBC, as specified in the specs
  final encoder = AES(
    Key(Uint8List.fromList(key)),
    mode: AESMode.cbc,
    padding: "PKCS7",
  );
  final iv = IV.fromSecureRandom(16);
  final encrypted = encoder.encrypt(
    Uint8List.fromList(utf8.encode(requestString)),
    iv: iv,
  ).bytes;
  final hmac = Hmac(sha256, key);

  // Encrypted payload
  final payload = jsonEncoder.convert({
    "data": HEX.encode(encrypted),
    "hmac": hmac.convert(encrypted).toString(),
    "iv": HEX.encode(iv.bytes),
  });

  // Opening the WalletConnect socket
  final channel = WebSocketChannel.connect(
      Uri.parse("wss://$bridgeHost?projectId=$walletConnectProjectId"),
  );

  // Listen for socket messages (but they won't come)
  channel.stream.listen((event) {
    print("Got wss message: $event");
  }, onError: (error) => {
    print("Got wss error: $error")
  }, onDone: () => {
    print("Got wss done event")
  });

  // Subscribing to the topic messages
  channel.sink.add(jsonEncoder.convert({
    "topic": topic,
    "type": "sub",
    "payload": "",
  }));

  // Subscribing to the peerId topic. Not sure if it's needed, I saw it in some sample
  channel.sink.add(jsonEncoder.convert({
    "topic": peerId,
    "type": "sub",
    "payload": "",
  }));

  // Sending the session request
  final pubRequest = jsonEncoder.convert({
    "topic": topic,
    "type": "pub",
    "payload": payload,
  });
  print(pubRequest);
  channel.sink.add(pubRequest);
}

[Svechnikov]

I made it work, here's the code, in case someone needs it:

import 'dart:convert';
import 'dart:math';
import 'dart:typed_data';

import 'package:crypto/crypto.dart';
import 'package:encrypt/encrypt.dart';
import 'package:hex/hex.dart';
import 'package:web_socket_channel/web_socket_channel.dart';

List<int> generateRandomKey() {
  final random = Random();
  return List.generate(32, (i) => random.nextInt(256));
}

void main() async {
  const bridgeHost = "bridge.walletconnect.org";
  const bridge = "https://$bridgeHost";

  final key = generateRandomKey();
  final topic = HEX.encode(generateRandomKey());

  final uri = "https://metamask.app.link/wc?uri=${Uri.encodeComponent("wc:$topic@1?bridge=$bridge&key=${HEX.encode(key)}")}";
  print(uri);

  const jsonEncoder = JsonEncoder();

  final requestString = jsonEncoder.convert({
    "id": 1,
    "jsonrpc": "2.0",
    "method": "wc_sessionRequest",
    "params": [
      {
        "peerId": topic,
        "peerMeta": {
          "name": "ShopSwipe",
          "description": "ShopSwipe marketplace",
          "url": "theping.co",
          "icons": ["https://gblobscdn.gitbook.com/spaces%2F-LJJeCjcLrr53DcT1Ml7%2Favatar.png?alt=media"]
        },
        "chainId": null,
      }
    ]
  });
  final encoder = AES(
    Key(Uint8List.fromList(key)),
    mode: AESMode.cbc,
    padding: "PKCS7",
  );
  final iv = IV.fromSecureRandom(16);
  final encrypted = encoder.encrypt(
    Uint8List.fromList(utf8.encode(requestString)),
    iv: iv,
  ).bytes;
  final hmac = Hmac(sha256, key);

  final payload = jsonEncoder.convert({
    "data": HEX.encode(encrypted),
    "hmac": HEX.encode(hmac.convert(encrypted + iv.bytes).bytes).toLowerCase(),
    "iv": HEX.encode(iv.bytes),
  });

  final channel = WebSocketChannel.connect(
      Uri.parse("wss://$bridgeHost"),
  );
  
  channel.stream.listen((event) {
    print("Got wss message: $event");
  }, onError: (error) => {
    print("Got wss error: $error")
  }, onDone: () => {
    print("Got wss done event")
  });

  channel.sink.add(jsonEncoder.convert({
    "topic": topic,
    "type": "sub",
    "payload": "",
  }));
  final pubRequest = jsonEncoder.convert({
    "topic": topic,
    "type": "pub",
    "payload": payload,
  });
  channel.sink.add(pubRequest);
}