WIP: Ledger wallets could not sign using ethereum

Users could not use Ledger hardware wallets to sign messages using an Ethereum key.

The command / response scheme used by Ledger to address the device is similar to the ISO/IEC 7816-4 smartcard protocol. Each command / response packet is called an APDU (application protocol data unit).

Each APDU is specific to Ledger application, that adds the support for a chain or functionality.

Solution: Use the Ledgereth library to send the Ethereum APDUs via ledgerblue.

setup.cfg

@@ -99,6 +99,8 @@ solana =
 tezos =
     pynacl
     aleph-pytezos==0.1.1
+ledger =
+    ledgereth==0.9.0
 docs =
     sphinxcontrib-plantuml
 

src/aleph/sdk/wallets/ledger/__init__.py

@@ -0,0 +1,3 @@
+from .ethereum import LedgerETHAccount
+
+__all__ = ["LedgerETHAccount"]

src/aleph/sdk/wallets/ledger/ethereum.py

@@ -0,0 +1,60 @@
+from typing import Dict, List, Optional
+
+from eth_typing import HexStr
+from ledgerblue.Dongle import Dongle
+from ledgereth import find_account, get_account_by_path, get_accounts
+from ledgereth.comms import init_dongle
+from ledgereth.messages import sign_message
+from ledgereth.objects import LedgerAccount, SignedMessage
+
+from ...chains.common import BaseAccount, get_verification_buffer
+
+
+class LedgerETHAccount(BaseAccount):
+    """Account using the Ethereum app on Ledger hardware wallets."""
+
+    CHAIN = "ETH"
+    CURVE = "secp256k1"
+    _account: LedgerAccount
+    _device: Dongle
+
+    def __init__(self, account: LedgerAccount, device: Optional[Dongle]):
+        self._account = account
+        self._device = device or init_dongle()
+
+    @staticmethod
+    def from_address(address: str, device: Dongle) -> Optional[LedgerAccount]:
+        return find_account(address=address, dongle=device, count=5)
+
+    @staticmethod
+    def from_path(path: str, device: Dongle) -> LedgerAccount:
+        return get_account_by_path(path_string=path, dongle=device)
+
+    async def sign_message(self, message: Dict) -> Dict:
+        """Sign a message inplace."""
+        message: Dict = self._setup_sender(message)
+
+        # TODO: Check why the code without a wallet uses `encode_defunct`.
+        msghash: bytes = get_verification_buffer(message)
+        sig: SignedMessage = sign_message(msghash, dongle=self._device)
+
+        signature: HexStr = sig.signature
+
+        message["signature"] = signature
+        return message
+
+    def get_address(self) -> str:
+        return self._account.address
+
+    def get_public_key(self) -> str:
+        raise NotImplementedError()
+
+
+def get_fallback_account() -> LedgerETHAccount:
+    """Returns the first account available on the device first device found."""
+    device: Dongle = init_dongle()
+    accounts: List[LedgerAccount] = get_accounts(dongle=device, count=1)
+    if not accounts:
+        raise ValueError("No account found on device")
+    account = accounts[0]
+    return LedgerETHAccount(account=account, device=device)

tests/unit/test_wallet_ethereum.py

@@ -0,0 +1,38 @@
+from dataclasses import asdict, dataclass
+from pathlib import Path
+from tempfile import NamedTemporaryFile
+
+import pytest
+from ledgereth.comms import init_dongle
+
+from aleph.sdk.chains.common import get_verification_buffer
+from aleph.sdk.chains.ethereum import verify_signature
+from aleph.sdk.exceptions import BadSignatureError
+from aleph.sdk.wallets.ledger.ethereum import LedgerETHAccount, get_fallback_account
+
+
+@dataclass
+class Message:
+    chain: str
+    sender: str
+    type: str
+    item_hash: str
+
+
+@pytest.mark.asyncio
+async def test_LedgerETHAccount(ethereum_account):
+    account: LedgerETHAccount = get_fallback_account()
+
+    message = Message("ETH", account.get_address(), "SomeType", "ItemHash")
+    signed = await account.sign_message(asdict(message))
+    assert signed["signature"]
+    assert len(signed["signature"]) == 132
+
+    address = account.get_address()
+    assert address
+    assert type(address) == str
+    assert len(address) == 42
+
+    pubkey = account.get_public_key()
+    assert type(pubkey) == str
+    assert len(pubkey) == 68