diff --git a/goodchain/src/classes/Transaction.py b/goodchain/src/classes/Transaction.py
index f175606..ed55bde 100644
--- a/goodchain/src/classes/Transaction.py
+++ b/goodchain/src/classes/Transaction.py
@@ -38,33 +38,33 @@ class Tx:
             return True
         
         else:
-            # total_in = 0
-            # total_out = 0
-            # message = self.__gather()
-            # for addr,amount in self.inputs:
-            #     found = False
-            #     for s in self.sigs:
-            #         if Signature.verify(message, s, addr):
-            #             found = True
-            #     if not found:
-            #         return False
-            #     if amount < 0:
-            #         return False
-            #     total_in = total_in + amount
-            # for addr in self.reqd:
-            #     found = False
-            #     for s in self.sigs:
-            #         if Signature.verify(message, s, addr):
-            #             found = True
-            #     if not found:
-            #         return False
-            # for addr,amount in self.outputs:
-            #     if amount < 0:
-            #         return False
-            #     total_out = total_out + amount
+            total_in = 0
+            total_out = 0
+            message = self.__gather()
+            for addr,amount in self.inputs:
+                found = False
+                for s in self.sigs:
+                    if Signature.verify(message, s, addr):
+                        found = True
+                if not found:
+                    return False
+                if amount < 0:
+                    return False
+                total_in = total_in + amount
+            for addr in self.reqd:
+                found = False
+                for s in self.sigs:
+                    if Signature.verify(message, s, addr):
+                        found = True
+                if not found:
+                    return False
+            for addr,amount in self.outputs:
+                if amount < 0:
+                    return False
+                total_out = total_out + amount
 
-            # if total_out > total_in:
-            #     return False        
+            if total_out > total_in:
+                return False        
             return True
 
     def __gather(self):
diff --git a/goodchain/src/helpers/SignatureHelper.py b/goodchain/src/helpers/SignatureHelper.py
index ff185ef..9c00340 100644
--- a/goodchain/src/helpers/SignatureHelper.py
+++ b/goodchain/src/helpers/SignatureHelper.py
@@ -3,6 +3,7 @@ from cryptography.hazmat.primitives.asymmetric import rsa
 from cryptography.hazmat.primitives import serialization
 from cryptography.hazmat.primitives import hashes
 from cryptography.hazmat.primitives.asymmetric import padding
+from cryptography.hazmat.backends import default_backend
 
 def generateKeys():
     private_key = rsa.generate_private_key(public_exponent=65537,key_size=2048)
@@ -43,29 +44,31 @@ def bytesToKeys(private_ser, public_ser):
 
 def publicBytesToKey(public_ser):
     public_key = serialization.load_pem_public_key(
-        public_ser
+        public_ser,
+        backend=default_backend()
     )
     return public_key
 
 def privateBytesToKey(private_ser):
     private_key = serialization.load_pem_private_key(
         private_ser,
-        password=None
+        password=None,
+        backend=default_backend()
     )
     return private_key
 
 def sign(message, private_key):
     message = bytes(str(message), 'utf-8')
-    key = privateBytesToKey(private_key)
-    signature = key.sign(
+    signature = private_key.sign(
         message,
         padding.PSS(mgf=padding.MGF1(hashes.SHA256()), salt_length=padding.PSS.MAX_LENGTH),
         hashes.SHA256()
         )
     return signature
 
-def verify(message, signature, public_key):
+def verify(message, signature, public_ser):
     message = bytes(str(message), 'utf-8')
+    public_key = publicBytesToKey(public_ser)
     try:
         public_key.verify(
             signature,