Update 11.md

problems/11.md

@@ -4,7 +4,7 @@ Now that we know about encryption we are ready to make our bank's transaction lo
 
 ## Problem
 
-What we want to is similar to when we added digital signatures. Generate a new encryption if one hasn't already be been generated. Then everytime we save the transaction log to disk encrypt it using the `secret_box` primitive. Remember to generate a new nonce every time you encrypt it and that you don't have to keep the nonce secret, it is perfectly safe to save this together with the cipher text.
+What we want to is similar to when we added digital signatures. Generate a new encryption if one hasn't already been generated. Then everytime we save the transaction log to disk encrypt it using the `secret_box` primitive. Remember to generate a new nonce every time you encrypt it and that you don't have to keep the nonce secret, it is perfectly safe to save this together with the cipher text.
 
 Then when the bank is starting up, read the transaction log from disk and decrypt it.