Fixed incorrect signature payload for extrinsics > 256 bytes; signatu…

…re payload should be a 32 bytes blake2b hash #49

substrateinterface/__init__.py

@@ -15,6 +15,8 @@
 # limitations under the License.
 
 import asyncio
+from hashlib import blake2b
+
 import binascii
 import json
 import logging
@@ -1105,6 +1107,9 @@ def generate_signature_payload(self, call, era=None, nonce=0, tip=0, include_cal
 
         signature_payload.encode(payload_dict)
 
+        if signature_payload.data.length > 256:
+            return ScaleBytes(data=blake2b(signature_payload.data.data, digest_size=32).digest())
+
         return signature_payload.data
 
     def create_signed_extrinsic(self, call, keypair: Keypair, era=None, nonce=None, tip=0, signature=None):

test/test_create_extrinsics.py

@@ -148,6 +148,34 @@ def test_payment_info(self):
 
         self.assertGreater(payment_info['partialFee'], 0)
 
+    def test_generate_signature_payload_lte_256_bytes(self):
+
+        call = self.kusama_substrate.compose_call(
+            call_module='System',
+            call_function='remark',
+            call_params={
+                '_remark': '0x' + ('01' * 177)
+            }
+        )
+
+        signature_payload = self.kusama_substrate.generate_signature_payload(call=call)
+
+        self.assertEqual(signature_payload.length, 256)
+
+    def test_generate_signature_payload_gt_256_bytes(self):
+
+        call = self.kusama_substrate.compose_call(
+            call_module='System',
+            call_function='remark',
+            call_params={
+                '_remark': '0x' + ('01' * 178)
+            }
+        )
+
+        signature_payload = self.kusama_substrate.generate_signature_payload(call=call)
+
+        self.assertEqual(signature_payload.length, 32)
+
 
 if __name__ == '__main__':
     unittest.main()