feat(account): Signing plain, defunct messages (for EIP-191) (refs: e…

…th-brownie#1163)

CHANGELOG.md

@@ -6,6 +6,7 @@ This changelog format is based on [Keep a Changelog](https://keepachangelog.com/
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased](https://github.com/eth-brownie/brownie)
+- Added `LocalAccount.sign_defunct_message` method to sign `EIP-191` text messages ([#1163](https://github.com/eth-brownie/brownie/pull/1163))
 
 ## [1.15.1](https://github.com/eth-brownie/brownie/tree/v1.15.1) - 2021-07-23
 ### Fixed

brownie/network/account.py

@@ -15,6 +15,7 @@
 from eip712.messages import EIP712Message, _hash_eip191_message
 from eth_account._utils.signing import sign_message_hash
 from eth_account.datastructures import SignedMessage
+from eth_account.messages import defunct_hash_message
 from eth_utils import keccak
 from eth_utils.applicators import apply_formatters_to_dict
 from hexbytes import HexBytes
@@ -815,6 +816,27 @@ def save(self, filename: str, overwrite: bool = False) -> str:
             json.dump(encrypted, fp)
         return str(json_file)
 
+    def sign_defunct_message(self, message: str) -> SignedMessage:
+        """Signs an `EIP-191` using this account's private key.
+
+        Args:
+            message: An text
+
+        Returns:
+            An eth_account `SignedMessage` instance.
+        """
+        msg_hash_bytes = defunct_hash_message(text=message)
+        eth_private_key = eth_keys.keys.PrivateKey(HexBytes(self.private_key))
+        (v, r, s, eth_signature_bytes) = sign_message_hash(eth_private_key, msg_hash_bytes)
+        return SignedMessage(
+            messageHash=msg_hash_bytes,
+            r=r,
+            s=s,
+            v=v,
+            signature=HexBytes(eth_signature_bytes),
+        )
+
+
     def sign_message(self, message: EIP712Message) -> SignedMessage:
         """Signs an `EIP712Message` using this account's private key.
 

docs/account-management.rst

@@ -94,6 +94,20 @@ To do so, add the account to the ``unlock`` setting in a project's :ref:`configu
 The unlocked accounts are automatically added to the :func:`Accounts <brownie.network.account.Accounts>` container.
 Note that you might need to fund the unlocked accounts manually.
 
+Signing Raw Text Messages (EIP-191)
+================
+
+To sign an EIP-191 message, use the :func:`LocalAccount.sign_defunct_message <brownie.network.account.LocalAccount.sign_defunct_message>` method to produce an ``eth_account`` `SignableMessage <https://eth-account.readthedocs.io/en/stable/eth_account.html#eth_account.messages.SignableMessage>`_ object:
+
+.. code-block:: python
+
+    >>> msg = f"It is my permission to spent 1000 SHIB from {local.address.lower()}"
+    >>> signed = local.sign_defunct_message(msg)
+    >>> type(signed)
+    <class 'eth_account.datastructures.SignedMessage'>
+    >>> signed.messageHash.hex()
+    '0x2a180b353c317ae903c063141592ec360b25be9f75c60ae16ca19f5578f70a50'
+
 Signing Messages
 ================
 

tests/network/account/test_accounts.py

@@ -152,3 +152,13 @@ class TestMessage(EIP712Message):
         signed.messageHash.hex()
         == "0x131c497d4b815213752a2a00564dcf667c3bf3f85a410ef8cb50050b51959c26"
     )
+
+
+def test_sign_defunct_message(accounts):
+    local = accounts.add(priv_key)
+    msg = f'I authorize Foundation to migrate my account to {local.address.lower()}'
+    signed = local.sign_defunct_message(msg)
+    assert (
+        signed.messageHash.hex()
+        == "0xb9bb14ce5c17b2b7217cfa638031a542b95fc25b18d42a61409066001d01351d"
+    )