Add unsafe_sign_hash migration path

eth_account/account.py

@@ -592,8 +592,9 @@ def signHash(self, message_hash, private_key):
             Instead, prefer :meth:`~eth_account.account.Account.sign_message`,
             which cannot accidentally sign a transaction.
 
-        .. CAUTION:: Deprecated for :meth:`~eth_account.account.Account.sign_message`.
-            This method will be removed in v0.6
+        .. CAUTION:: Deprecated for
+            :meth:`~eth_account.account.Account.unsafe_sign_hash`.
+            This method will be removed in v0.13
 
         :param message_hash: the 32-byte message hash to be signed
         :type message_hash: hex str, bytes or int
@@ -604,12 +605,34 @@ def signHash(self, message_hash, private_key):
         :rtype: ~eth_account.datastructures.SignedMessage
         """
         warnings.warn(
-            "signHash is deprecated in favor of sign_message",
+            "signHash is deprecated in favor of sign_message or unsafe_sign_hash"
+            " depending on your use case",
             category=DeprecationWarning,
             stacklevel=2,
         )
         return self._sign_hash(message_hash, private_key)
 
+    @combomethod
+    def unsafe_sign_hash(self, message_hash, private_key):
+        """
+        Sign the provided hash.
+
+        .. WARNING:: *Never* sign a hash that you didn't generate,
+            it can be an arbitrary transaction. For example, it might
+            send all of your account's ether to an attacker.
+            Instead, prefer :meth:`~eth_account.account.Account.sign_message`,
+            which cannot accidentally sign a transaction.
+
+        :param message_hash: the 32-byte message hash to be signed
+        :type message_hash: hex str, bytes or int
+        :param private_key: the key to sign the message with
+        :type private_key: hex str, bytes, int or :class:`eth_keys.datatypes.PrivateKey`
+        :returns: Various details about the signature - most
+          importantly the fields: v, r, and s
+        :rtype: ~eth_account.datastructures.SignedMessage
+        """
+        return self._sign_hash(message_hash, private_key)
+
     @combomethod
     def _sign_hash(
         self,

eth_account/messages.py

@@ -331,8 +331,9 @@ def defunct_hash_message(
     """
     Convert the provided message into a message hash, to be signed.
 
-    .. CAUTION:: Intended for use with the deprecated
-        :meth:`eth_account.account.Account.signHash`.
+    .. CAUTION:: Intended for use with
+        :meth:`eth_account.account.Account.unsafe_sign_hash`.
+        or the deprecated :meth:`eth_account.account.Account.signHash`.
         This is for backwards compatibility only. All new implementations
         should use :meth:`encode_defunct` instead.
 

eth_account/signers/base.py

@@ -53,8 +53,26 @@ def signHash(self, message_hash):
         but without specifying the private key.
 
         .. CAUTION:: Deprecated for
-            :meth:`~eth_account.signers.base.BaseAccount.sign_message`.
-            To be removed in v0.6
+            :meth:`~eth_account.signers.base.BaseAccount.unsafe_sign_hash`.
+            To be removed in v0.13
+
+        :param bytes message_hash: 32 byte hash of the message to sign
+        """
+
+    @abstractmethod
+    def unsafe_sign_hash(self, message_hash):
+        """
+        Sign the hash of a message.
+
+        .. WARNING:: *Never* sign a hash that you didn't generate,
+            it can be an arbitrary transaction. For example, it might
+            send all of your account's ether to an attacker.
+            Instead, prefer :meth:`~eth_account.account.Account.sign_message`,
+            which cannot accidentally sign a transaction.
+
+        This uses the same structure
+        as in :meth:`~eth_account.account.Account.unsafe_sign_hash`
+        but without specifying the private key.
 
         :param bytes message_hash: 32 byte hash of the message to sign
         """

eth_account/signers/local.py

@@ -70,6 +70,12 @@ def signHash(self, message_hash):
             private_key=self.key,
         )
 
+    def unsafe_sign_hash(self, message_hash):
+        return self._publicapi.unsafe_sign_hash(
+            message_hash,
+            private_key=self.key,
+        )
+
     def sign_message(self, signable_message):
         """
         Generate a string with the encrypted key.

newsfragments/263.deprecation.rst

@@ -0,0 +1 @@
+Provide an upgrade path to remove ``signHash``

tests/core/test_accounts.py

@@ -441,6 +441,46 @@ def test_sign_message_against_sign_hash_as_hex(keyed_acct, message_bytes):
     assert signed_via_hash_hex == signed_via_message_hex
 
 
+@given(st.binary())
+def test_sign_message_against_unsafe_sign_hash_as_bytes(keyed_acct, message_bytes):
+    # sign via hash
+    msg_hash = defunct_hash_message(message_bytes)
+    signed_via_hash = keyed_acct.unsafe_sign_hash(msg_hash)
+
+    # sign via message
+    signable_message = encode_defunct(message_bytes)
+    signed_via_message = keyed_acct.sign_message(signable_message)
+
+    assert signed_via_hash == signed_via_message
+
+
+@given(st.binary())
+def test_sign_message_against_unsafe_sign_hash_as_hex(keyed_acct, message_bytes):
+    message_hex = to_hex(message_bytes)
+
+    # sign via hash
+    msg_hash_hex = defunct_hash_message(hexstr=message_hex)
+    signed_via_hash_hex = keyed_acct.unsafe_sign_hash(msg_hash_hex)
+
+    # sign via message
+    signable_message_hex = encode_defunct(hexstr=message_hex)
+    signed_via_message_hex = keyed_acct.sign_message(signable_message_hex)
+
+    assert signed_via_hash_hex == signed_via_message_hex
+
+
+@given(st.text())
+def test_sign_message_against_unsafe_sign_hash_as_text(keyed_acct, message_text):
+    # sign via hash
+    msg_hash = defunct_hash_message(text=message_text)
+    signed_via_hash = keyed_acct.unsafe_sign_hash(msg_hash)
+
+    # sign via message
+    signable_message = encode_defunct(text=message_text)
+    signed_via_message = keyed_acct.sign_message(signable_message)
+    assert signed_via_hash == signed_via_message
+
+
 @pytest.mark.parametrize(
     "message, key, expected_bytes, expected_hash, v, r, s, signature",
     (