Add support for signing messages using LedgerHQ wallet on Ethereum (#51)

Feature: 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.

README.md

@@ -43,3 +43,31 @@ or
 ```shell
 $ python setup.py develop
 ```
+
+## Usage with LedgerHQ hardware
+
+The SDK supports signatures using [app-ethereum](https://github.com/LedgerHQ/app-ethereum),
+the Ethereum app for the Ledger hardware wallets.
+
+This has been tested successfully on Linux (amd64).
+Let us know if it works for you on other operating systems.
+
+Using a Ledger device on Linux requires root access or the setup of udev rules.
+
+Unlocking the device is required before using the relevant SDK functions.
+
+### Debian / Ubuntu
+
+Install [ledger-wallets-udev](https://packages.debian.org/bookworm/ledger-wallets-udev).
+
+`sudo apt-get install ledger-wallets-udev`
+
+### On NixOS
+
+Configure `hardware.ledger.enable = true`.
+
+### Other Linux systems
+
+See https://github.com/LedgerHQ/udev-rules
+
+

docker/python-3.10.dockerfile

@@ -29,7 +29,7 @@ USER root
 RUN chown -R user:user /opt/aleph-sdk-python
 
 RUN git config --global --add safe.directory /opt/aleph-sdk-python
-RUN pip install -e .[testing,ethereum,solana,tezos]
+RUN pip install -e .[testing,ethereum,solana,tezos,ledger]
 
 RUN mkdir /data
 RUN chown user:user /data

docker/python-3.11.dockerfile

@@ -29,7 +29,7 @@ USER root
 RUN chown -R user:user /opt/aleph-sdk-python
 
 RUN git config --global --add safe.directory /opt/aleph-sdk-python
-RUN pip install -e .[testing,ethereum,solana,tezos]
+RUN pip install -e .[testing,ethereum,solana,tezos,ledger]
 
 RUN mkdir /data
 RUN chown user:user /data

docker/python-3.9.dockerfile

@@ -29,7 +29,7 @@ USER root
 RUN chown -R user:user /opt/aleph-sdk-python
 
 RUN git config --global --add safe.directory /opt/aleph-sdk-python
-RUN pip install -e .[testing,ethereum,solana,tezos]
+RUN pip install -e .[testing,ethereum,solana,tezos,ledger]
 
 RUN mkdir /data
 RUN chown user:user /data

docker/ubuntu-20.04.dockerfile

@@ -34,7 +34,7 @@ USER root
 RUN chown -R user:user /opt/aleph-sdk-python
 
 RUN git config --global --add safe.directory /opt/aleph-sdk-python
-RUN pip install -e .[testing,ethereum,solana,tezos]
+RUN pip install -e .[testing,ethereum,solana,tezos,ledger]
 
 RUN mkdir /data
 RUN chown user:user /data

docker/ubuntu-22.04.dockerfile

@@ -34,7 +34,7 @@ USER root
 RUN chown -R user:user /opt/aleph-sdk-python
 
 RUN git config --global --add safe.directory /opt/aleph-sdk-python
-RUN pip install -e .[testing,ethereum,solana,tezos]
+RUN pip install -e .[testing,ethereum,solana,tezos,ledger]
 
 RUN mkdir /data
 RUN chown user:user /data

setup.cfg

@@ -99,6 +99,8 @@ solana =
 tezos =
     pynacl
     aleph-pytezos==0.1.1
+ledger =
+    ledgereth==0.9.0
 docs =
     sphinxcontrib-plantuml
 
@@ -124,12 +126,14 @@ extras = True
 addopts =
     --cov aleph.sdk --cov-report term-missing
     --verbose
+    -m "not ledger_hardware"
 norecursedirs =
     dist
     build
     .tox
 testpaths = tests
-
+markers =
+    "ledger_hardware: marks tests as requiring ledger hardware"
 [aliases]
 dists = bdist_wheel
 

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 +1,88 @@
+from __future__ import annotations
+
+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: Dongle):
+        """Initialize an aleph.im account instance that relies on a LedgerHQ
+        device and the Ethereum Ledger application for signatures.
+
+        See the static methods `self.from_address(...)` and `self.from_path(...)`
+        for an easier method of instantiation.
+        """
+        self._account = account
+        self._device = device
+
+    @staticmethod
+    def from_address(
+        address: str, device: Optional[Dongle] = None
+    ) -> Optional[LedgerETHAccount]:
+        """Initialize an aleph.im account from a LedgerHQ device from
+        a known wallet address.
+        """
+        device = device or init_dongle()
+        account = find_account(address=address, dongle=device, count=5)
+        return LedgerETHAccount(
+            account=account,
+            device=device,
+        )
+
+    @staticmethod
+    def from_path(path: str, device: Optional[Dongle] = None) -> LedgerETHAccount:
+        """Initialize an aleph.im account from a LedgerHQ device from
+        a known wallet account path."""
+        device = device or init_dongle()
+        account = get_account_by_path(path_string=path, dongle=device)
+        return LedgerETHAccount(
+            account=account,
+            device=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:
+        """Obtaining the public key is not supported by the ledgereth library
+        we use, and may not be supported by LedgerHQ devices at all.
+        """
+        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 +1,46 @@
+from dataclasses import asdict, dataclass
+
+import pytest
+
+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.ledger_hardware
+@pytest.mark.asyncio
+async def test_ledger_eth_account():
+    account: LedgerETHAccount = get_fallback_account()
+
+    address = account.get_address()
+    assert address
+    assert type(address) is str
+    assert len(address) == 42
+
+    message = Message("ETH", account.get_address(), "SomeType", "ItemHash")
+    signed = await account.sign_message(asdict(message))
+    assert signed["signature"]
+    assert len(signed["signature"]) == 132
+
+    verify_signature(
+        signed["signature"], signed["sender"], get_verification_buffer(signed)
+    )
+
+    with pytest.raises(BadSignatureError):
+        signed["signature"] = signed["signature"][:-8] + "cafecafe"
+
+        verify_signature(
+            signed["signature"], signed["sender"], get_verification_buffer(signed)
+        )
+
+    with pytest.raises(NotImplementedError):
+        account.get_public_key()