diff --git a/pbc_client/__init__.py b/pbc_client/__init__.py
index e3c7d3b..eaf0892 100644
--- a/pbc_client/__init__.py
+++ b/pbc_client/__init__.py
@@ -55,7 +55,7 @@ def shard_id_for_address(address: str | Address) -> str:
     if address is None:
         msg = 'Address must not be None'
         raise TypeError(msg)
-    if address.endswith('a'):
+    if address.endswith(('a','d', 'c')):
         return 'shards/Shard0/'
     if address.endswith('2'):
         return 'shards/Shard1/'
@@ -81,7 +81,10 @@ class SenderAuthentication:
         return Address(b'\0' + hashed._bytes[-20:])
 
     def sign_hash(self, _hash: HashSha256) -> Signature:
-        return Signature(self._signing_key().sign(_hash._bytes))
+        signing_key = self._signing_key()
+        signature = signing_key.sign_digest_deterministic(_hash._bytes)
+
+        return Signature(b'\0' + signature)
 
     def _signing_key(self):
         secret_exponent = int(self.secret_key, 16)
@@ -102,6 +105,7 @@ def sign_transaction(
     contract_address: Address | str,
     transaction_rpc: bytes,
 ) -> SignedTransaction:
+    print(contract_address)
     sender = sender_authentication.sender_address
     valid_to_time: int = int(time.time() + TRANSACTION_VALIDITY_DURATION) * 1000
 
@@ -112,11 +116,9 @@ def sign_transaction(
         Transaction(Address.from_string(contract_address), transaction_rpc),
     )
 
-    transaction_hash_bytes = inner.rpc_serialize() + chain_id.encode('utf8')
-
-    transaction_hash: HashSha256 = HashSha256.of_bytes(transaction_hash_bytes)
-    signature: Signature = sender_authentication.sign_hash(transaction_hash)
-    return SignedTransaction(inner, signature, transaction_hash)
+    signature: Signature = sender_authentication.sign_hash(inner.hash(chain_id))
+    print(signature)
+    return SignedTransaction(inner, signature)
 
 
 @dataclasses.dataclass(frozen=True)
@@ -146,6 +148,14 @@ class PbcClient:
             rpc,
         )
 
+        print('RPC', signed_transaction.rpc_serialize())
+        print('RPC length', len(signed_transaction.rpc_serialize()))
+
+        assert len(signed_transaction.inner.transaction.rpc_serialize()) == 25
+        assert len(signed_transaction.signature.rpc_serialize()) == 65
+        assert len(signed_transaction.inner.rpc_serialize()) == 49
+        assert len(signed_transaction.rpc_serialize()) == 114
+
         return self.send_signed_transaction(signed_transaction)
 
     def send_signed_transaction(self, signed_transaction: SignedTransaction):
@@ -156,9 +166,11 @@ class PbcClient:
             ),
         )
 
+        print(signed_transaction)
         transaction_payload: str = base64.b64encode(
             signed_transaction.rpc_serialize(),
         ).decode('utf8')
+        print(transaction_payload)
         self._get_json(
             url,
             data={'transactionPayload': transaction_payload},
@@ -248,6 +260,7 @@ class PbcClient:
             shard=shard_id_for_address(address),
             address=address,
         )
+        print(url)
         return self._get_json(url, method='GET')[0]['nonce']
 
     def get_contract_state(self, address: str) -> tuple[dict, datetime.datetime]:
diff --git a/pbc_client/pbc_types.py b/pbc_client/pbc_types.py
index b6941d6..392cae9 100644
--- a/pbc_client/pbc_types.py
+++ b/pbc_client/pbc_types.py
@@ -31,7 +31,7 @@ class Signature:
     _bytes: bytes
 
     def __post_init__(self):
-        assert len(self._bytes) == 64, len(self._bytes)
+        assert len(self._bytes) == 65, len(self._bytes)
 
     def rpc_serialize(self) -> bytes:
         return self._bytes
@@ -81,22 +81,26 @@ class SignedTransactionInnerPart:
 
     def rpc_serialize(self) -> bytes:
         return (
-            self.nonce.to_bytes(4, 'big')
+            self.nonce.to_bytes(8, 'big')
             + self.valid_to_time.to_bytes(8, 'big')
             + self.gas_cost.to_bytes(8, 'big')
             + self.transaction.rpc_serialize()
         )
 
+    def hash(self, chain_id: str) -> HashSha256:
+        return HashSha256.of_bytes(self.rpc_serialize() + chain_id.encode('utf8'))
+
 
 @dataclasses.dataclass(frozen=True)
 class SignedTransaction:
     inner: SignedTransactionInnerPart
     signature: Signature
-    hash: HashSha256
+
+    def hash(self, chain_id: str) -> HashSha256:
+        return self.inner.hash(chain_id)
 
     def rpc_serialize(self) -> bytes:
         return (
-            self.inner.rpc_serialize()
-            + self.signature.rpc_serialize()
-            + self.hash.rpc_serialize()
+            self.signature.rpc_serialize()
+            + self.inner.rpc_serialize()
         )