It is possible that an adversary may attack to conventional key encapsulation mechanism (KEM) and data encapsulation mechanism (DEM) structure, if any weakness exists in these algorithms. In order to prevent such kind of attacks and to make the KEM-DEM structure secure in a very strong sense, we propose a scramble algorithm in which KEM and DEM are combined and permuted, then encrypted with symmetric key driving into one block. In addition, for a long term communication between two nodes, we propose a new scheme Combined KEM-DEM which provides message integrity and sender's identity control via an integrated session key. In this method, each message is encrypted with different symmetric key and whole communication traffic is controlled. Simulations made using RSA with different key lengths (256, 512, and 1024 bits) show that by employing the Combined KEM-DEM scheme, computation times of KEM for the encryption and decryption are reduced by 40% as compared to Tag-KEM/DEM  and Fujisaki-Okamoto's KEM-DEM  schemes.