raise new BadSignatureError exception instead of boolean check for ve…

…rify_signature()

src/aleph/sdk/chains/ethereum.py

@@ -4,7 +4,9 @@
 from eth_account import Account
 from eth_account.messages import encode_defunct
 from eth_account.signers.local import LocalAccount
+from eth_keys.exceptions import BadSignature as EthBadSignatureError
 
+from ..exceptions import BadSignatureError
 from .common import (
     BaseAccount,
     get_fallback_private_key,
@@ -47,13 +49,15 @@ def verify_signature(
     signature: Union[bytes, str],
     public_key: Union[bytes, str],
     message: Union[bytes, str],
-) -> bool:
+):
     """
     Verifies a signature.
     Args:
         signature: The signature to verify. Can be a hex encoded string or bytes.
         public_key: The sender's public key to use for verification. Can be a checksummed, hex encoded string or bytes.
         message: The message to verify. Can be an utf-8 string or bytes.
+    Raises:
+        BadSignatureError: If the signature is invalid.
     """
     if isinstance(signature, str):
         if signature.startswith("0x"):
@@ -71,9 +75,7 @@ def verify_signature(
     message_hash = encode_defunct(text=message)
     try:
         address = Account.recover_message(message_hash, signature=signature)
-        if address == public_key:
-            return True
-        else:
-            return False
-    except Exception:
-        return False
+        if address != public_key:
+            raise BadSignatureError
+    except (EthBadSignatureError, BadSignatureError) as e:
+        raise BadSignatureError from e

src/aleph/sdk/chains/sol.py

@@ -4,11 +4,12 @@
 from typing import Dict, Optional, Union
 
 import base58
-from nacl.exceptions import BadSignatureError
+from nacl.exceptions import BadSignatureError as NaclBadSignatureError
 from nacl.public import PrivateKey, SealedBox
 from nacl.signing import SigningKey, VerifyKey
 
 from ..conf import settings
+from ..exceptions import BadSignatureError
 from .common import BaseAccount, get_verification_buffer
 
 
@@ -88,13 +89,15 @@ def verify_signature(
     signature: Union[bytes, str],
     public_key: Union[bytes, str],
     message: Union[bytes, str],
-) -> bool:
+):
     """
     Verifies a signature.
     Args:
         signature: The signature to verify. Can be a base58 encoded string or bytes.
         public_key: The public key to use for verification. Can be a base58 encoded string or bytes.
         message: The message to verify. Can be an utf-8 string or bytes.
+    Raises:
+        BadSignatureError: If the signature is invalid.
     """
     if isinstance(signature, str):
         signature = base58.b58decode(signature)
@@ -104,6 +107,5 @@ def verify_signature(
         public_key = base58.b58decode(public_key)
     try:
         VerifyKey(public_key).verify(message, signature)
-        return True
-    except BadSignatureError:
-        return False
+    except NaclBadSignatureError as e:
+        raise BadSignatureError from e

src/aleph/sdk/exceptions.py

@@ -34,3 +34,11 @@ class InvalidMessageError(BroadcastError):
     """
 
     pass
+
+
+class BadSignatureError(Exception):
+    """
+    The signature of a message is invalid.
+    """
+
+    pass

tests/unit/test_chain_ethereum.py

@@ -6,6 +6,7 @@
 
 from aleph.sdk.chains.common import get_verification_buffer
 from aleph.sdk.chains.ethereum import get_fallback_account, verify_signature
+from aleph.sdk.exceptions import BadSignatureError
 
 
 @dataclass
@@ -58,11 +59,33 @@ async def test_verify_signature(ethereum_account):
     await account.sign_message(message)
     assert message["signature"]
 
-    assert verify_signature(
+    verify_signature(
         message["signature"], message["sender"], get_verification_buffer(message)
     )
 
 
+@pytest.mark.asyncio
+async def test_verify_signature_with_forged_signature(ethereum_account):
+    account = ethereum_account
+
+    message = asdict(
+        Message(
+            "ETH",
+            account.get_address(),
+            "POST",
+            "SomeHash",
+        )
+    )
+    await account.sign_message(message)
+    assert message["signature"]
+
+    forged_signature = "0x" + "0" * 130
+    with pytest.raises(BadSignatureError):
+        verify_signature(
+            forged_signature, message["sender"], get_verification_buffer(message)
+        )
+
+
 @pytest.mark.asyncio
 async def test_decrypt_secp256k1(ethereum_account):
     account = ethereum_account

tests/unit/test_chain_solana.py

@@ -9,6 +9,7 @@
 
 from aleph.sdk.chains.common import get_verification_buffer
 from aleph.sdk.chains.sol import SOLAccount, get_fallback_account, verify_signature
+from aleph.sdk.exceptions import BadSignatureError
 
 
 @dataclass
@@ -87,6 +88,23 @@ async def test_verify_signature(solana_account):
     raw_signature = json.loads(message["signature"])["signature"]
     assert type(raw_signature) == str
 
-    assert verify_signature(
-        raw_signature, message["sender"], get_verification_buffer(message)
+    verify_signature(raw_signature, message["sender"], get_verification_buffer(message))
+
+
+@pytest.mark.asyncio
+async def test_verify_signature_with_forged_signature(solana_account):
+    message = asdict(
+        Message(
+            "SOL",
+            solana_account.get_address(),
+            "POST",
+            "SomeHash",
+        )
     )
+    await solana_account.sign_message(message)
+    assert message["signature"]
+    # create forged 64 bit signature from random bytes
+    forged = base58.b58encode(bytes(64)).decode("utf-8")
+
+    with pytest.raises(BadSignatureError):
+        verify_signature(forged, message["sender"], get_verification_buffer(message))