From ccfca49ea091a718be822c654c6a5314ec899276 Mon Sep 17 00:00:00 2001
From: John Peterson <98187317+John-peterson-coinbase@users.noreply.github.com>
Date: Tue, 1 Oct 2024 19:25:02 -0400
Subject: [PATCH] feat(PSDK-499): Message Hashing Utilities for EIP-191/712
 (#23)

---
 CHANGELOG.md             |  1 +
 cdp/__init__.py          |  3 +++
 cdp/hash_utils.py        | 40 ++++++++++++++++++++++++++++++++++++
 tests/test_hash_utils.py | 44 ++++++++++++++++++++++++++++++++++++++++
 4 files changed, 88 insertions(+)
 create mode 100644 cdp/hash_utils.py
 create mode 100644 tests/test_hash_utils.py

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 585a06a..de6e6e6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@
 - Contract invocation support.
 - Arbitrary message signing support.
 - Deploy ERC20, ERC721, and ERC1155 smart contracts.
+- Hashing utilities for EIP-191 / EIP-712 data messages.
 
 ### Fixed
 
diff --git a/cdp/__init__.py b/cdp/__init__.py
index 0c2f049..33a4168 100644
--- a/cdp/__init__.py
+++ b/cdp/__init__.py
@@ -6,6 +6,7 @@
 from cdp.cdp import Cdp
 from cdp.contract_invocation import ContractInvocation
 from cdp.faucet_transaction import FaucetTransaction
+from cdp.hash_utils import hash_message, hash_typed_data_message
 from cdp.payload_signature import PayloadSignature
 from cdp.smart_contract import SmartContract
 from cdp.sponsored_send import SponsoredSend
@@ -34,4 +35,6 @@
     "SponsoredSend",
     "PayloadSignature",
     "SmartContract",
+    "hash_message",
+    "hash_typed_data_message",
 ]
diff --git a/cdp/hash_utils.py b/cdp/hash_utils.py
new file mode 100644
index 0000000..70879c6
--- /dev/null
+++ b/cdp/hash_utils.py
@@ -0,0 +1,40 @@
+from typing import Any
+
+from eth_account.messages import _hash_eip191_message, encode_defunct, encode_typed_data
+from eth_utils import to_hex
+
+
+def hash_message(message_text: str) -> str:
+    """Hashes a message according to EIP-191 and returns the hash as a 0x-prefixed hexadecimal string.
+
+    This function prefixes the message with the standard Ethereum message prefix and hashes it using Keccak-256.
+
+    Args:
+        message_text (str): The message to hash.
+
+    Returns:
+        str: The 0x-prefixed hexadecimal string of the message hash.
+
+    """
+    message = encode_defunct(text=message_text)
+    message_hash = _hash_eip191_message(message)
+
+    return to_hex(message_hash)
+
+
+def hash_typed_data_message(typed_data: dict[str, Any]) -> str:
+    """Hashes typed data according to EIP-712 and returns the hash as a 0x-prefixed hexadecimal string.
+
+    This function encodes the typed data as per EIP-712 and hashes it using Keccak-256.
+
+    Args:
+        typed_data (dict): The typed data to hash, following the EIP-712 specification.
+
+    Returns:
+        str: The 0x-prefixed hexadecimal string of the typed data hash.
+
+    """
+    typed_data_message = encode_typed_data(full_message=typed_data)
+    typed_data_message_hash = _hash_eip191_message(typed_data_message)
+
+    return to_hex(typed_data_message_hash)
diff --git a/tests/test_hash_utils.py b/tests/test_hash_utils.py
new file mode 100644
index 0000000..318d7ff
--- /dev/null
+++ b/tests/test_hash_utils.py
@@ -0,0 +1,44 @@
+from cdp.hash_utils import hash_message, hash_typed_data_message
+
+
+def test_hash_message():
+    """Test hash_message utility method."""
+    message_hash = hash_message("Hello, EIP-191!")
+    assert message_hash == "0x54c2490066f5b62dd2e2ea2310c2b3d63039bbce5e3f96175a1b66a0c484e74f"
+
+
+def test_hash_typed_data_message():
+    """Test hash_typed_data_message utility method."""
+    typed_data = {
+        "types": {
+            "EIP712Domain": [
+                {"name": "name", "type": "string"},
+                {"name": "version", "type": "string"},
+                {"name": "chainId", "type": "uint256"},
+                {"name": "verifyingContract", "type": "address"},
+            ],
+            "Person": [{"name": "name", "type": "string"}, {"name": "wallet", "type": "address"}],
+            "Mail": [
+                {"name": "from", "type": "Person"},
+                {"name": "to", "type": "Person"},
+                {"name": "contents", "type": "string"},
+            ],
+        },
+        "primaryType": "Mail",
+        "domain": {
+            "name": "Ether Mail",
+            "version": "1",
+            "chainId": 1,
+            "verifyingContract": "0xCcCCccccCCCCcCCCCCCcCcCccCcCCCcCcccccccC",
+        },
+        "message": {
+            "from": {"name": "Alice", "wallet": "0xCD2a3d9F938E13CD947Ec05AbC7FE734Df8DD826"},
+            "to": {"name": "Bob", "wallet": "0xbBbBBBBbbBBBbbbBbbBbbbbBBbBbbbbBbBbbBBbB"},
+            "contents": "Hello, Bob!",
+        },
+    }
+    typed_data_message_hash = hash_typed_data_message(typed_data)
+    assert (
+        typed_data_message_hash
+        == "0x4644890d40a2ebb8cbf599801c4412c03f8027f04044d0dd12a0605fbd72bb8b"
+    )