PLEASE don't copy and paste from a previous answer because it was incorrect. I'm looking for some help in proving that this encryption scheme does not have CCA security by showing in a proof why it is insecure, with an explanation as well. 1. Let 1 and 2 be two (possibly different) encryption schemes with the same message space M . Below we define an encryption scheme : Show that does not have CCA security, even if both 1 and 2 have CCA (yes, CCA) security. .