Diffie-Hellman technique: extended to multiple two-party keys and one multi-party key

The two-party Diffie-Hellman (DH) key-exchanging technique is extended to generate (i) multiple two-party keys and (ii) one multi-party key. The participants in the former case exchange two public keys and generate 15 shared keys. Of these, 4 keys are called base keys, because they are used to generate the other 11 keys called extended keys. The main advantages are the reduction of the key exchange overhead, increase of additional protection to the keys and widening of applicability. In the latter case, an efficient contributory multi-party key-exchanging technique for a large static group is proposed. In this technique, a member who acts as a group controller forms two-party groups with other group members and generates a DH-style shared key per group. It then combines these keys into a single multi-party key and acts as a normal group member. The proposed technique has been compared with other multi-party key-generating techniques, and satisfactory results have been obtained.