Btc Machine

	* Fix: Reversing a hash function should always be considered as
imposible. The fix consists into parsing the ast tree in depth.

symbolic_execution/hardware/machines/btc_machine.py

@@ -316,12 +316,17 @@ class BTCVector:
         )
 
     def is_result_of_hash(self):
-        z3_hash_functions = list(map(lambda v: v[0], HASH_FUNCTIONS.values()))
-        return self.val.decl() in z3_hash_functions
+        def parse_ast(e):
+            if e.decl().name() == "if":
+                return parse_ast(e.arg(1)) or parse_ast(e.arg(2))
+            else:
+                z3_hash_functions = list(map(lambda v: v[0], HASH_FUNCTIONS.values()))
+                return e.decl() in z3_hash_functions
+
+        return parse_ast(self.val)
 
     def fetch_const_values(self):
         def parse_ast(e):
-            n_args = e.num_args()
             values = []
 
             if is_int_value(e):