Provably secure group key exchange

The rapid and promising development of applications and communication systems designed for groups of participants implies exigence of mechanisms providing adequate security properties. These mechanisms can be designed based on the foundations of cryptography. Group Key Exchange (GKE) protocols are multi-party cryptographic protocols those participants compute a shared secret key that can then be used in conjunction with cryptographic encryption schemes and message authentication codes for the purpose of privacy, confidentiality and group authentication. Security confidence of modern cryptographic constructions can be increased via adequate security proofs. The paradigm of provable security gains in importance for all kinds of cryptographic schemes, including GKE protocols those security issues represent the scope of this dissertation.

We give an analytical overview of the state-of-the-art research in this area and identify strengths and weaknesses of many previous approaches. We suggest a new approach in form of a security model those stronger definitions provide background for more confident security analyzes and proofs. Additionally, we present a number of generic solutions - compilers - that can be applied to independently designed GKE protocols in order to enhance security thereof. Finally, we present a concrete GKE protocol that provably satisfies the apparently strongest currently available formally specified security requirements.