CIP-0008: Allow for signing with stake key directly

In the browser, if a user specifies the stake key as part of CIP-0030
the message returned in JSON has the COSE key as the staking key.  The
verify() method correctly detects this, but the sign() method does not.
This change detects if a stake SigningKey type was passed in and if so,
sign with a stake key.

[ Documentation: pydoc updates ]
[ Testing: python -m build, manual test in CLI ]

Author: thaddeusdiamond

pycardano/cip/cip8.py

@@ -13,6 +13,8 @@
 from pycardano.key import (
     PaymentVerificationKey,
     SigningKey,
+    StakeExtendedSigningKey,
+    StakeSigningKey,
     StakeVerificationKey,
     VerificationKey,
 )
@@ -27,7 +29,9 @@ def sign(
     attach_cose_key: bool = False,
     network: Network = Network.MAINNET,
 ) -> Union[str, dict]:
-    """Sign an arbitrary message with a payment key following CIP-0008.
+    """Sign an arbitrary message with a payment or stake key following CIP-0008.
+    Note that a stake key passed in must be of type StakeSigningKey or
+    StakeExtendedSigningKey to be detected.
 
     Args:
         message (str): Message to be signed
@@ -43,11 +47,16 @@ def sign(
     # derive the verification key
     verification_key = VerificationKey.from_signing_key(signing_key)
 
+    if isinstance(signing_key, StakeSigningKey) or isinstance(signing_key, StakeExtendedSigningKey):
+        address = Address(payment_part=None, staking_part=verification_key.hash(), network=network)
+    else:
+        address = Address(payment_part=verification_key.hash(), staking_part=None, network=network)
+
     # create the message object, attach verification key to the header
     msg = Sign1Message(
         phdr={
             Algorithm: EdDSA,
-            "address": Address(verification_key.hash(), network=network).to_primitive(),
+            "address": address.to_primitive(),
         },
         payload=message.encode("utf-8"),
     )

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "pycardano"
-version = "0.7.2"
+version = "0.7.3"
 classifiers = [
     "Intended Audience :: Developers",
     "License :: OSI Approved :: MIT License",