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We motivate and present two designs for the composition of the authentication protocol, Kerberos, and the key transport protocol, Multimedia Internet KEYing (MIKEY) for authenticated transport of cryptographic keys for secure group-communication in enterprise and public-safety settings. A technical challenge, and our main contribution, is the analysis of the security of the composition. Towards this, we design our compositions to have intuitive appeal and thereby less prone to security vulnerabilities. We then employ protocol composition logic (PCL), a state-of-the-art approach for analyzing our composition. For this, we first articulate two properties that are of interest. Both properties are on the group key that is transported; we call them Group Key Confidentiality and Acquisition. Group Key Confidentiality is the property that if a principal possesses the key, then it is an authorized member of the group. Group Key Acquisition is the property that if a principal is a member of the group, then it is able to acquire the group key. In the course of our rigorous analysis, we discovered a flaw in our first design, which we point out, and which lead us to our second design. We have implemented both designs starting with the publicly available reference implementation of Kerberos, and an open-source implementation of MIKEY. Our implementations are available as open-source. We discuss our experience from the implementation, and present empirical results. [ABSTRACT FROM PUBLISHER]

This paper presents a secure protocol for spontaneous wireless ad hoc networks which uses an hybrid symmetric/asymmetric scheme and the trust between users in order to exchange the initial data and to exchange the secret keys that will be used to encrypt the data. Trust is based on the first visual contact between users. Our proposal is a complete self-configured secure protocol that is able to create the network and share secure services without any infrastructure. The network allows sharing resources and offering new services among users in a secure environment. The protocol includes all functions needed to operate without any external support. We have designed and developed it in devices with limited resources. Network creation stages are detailed and the communication, protocol messages, and network management are explained. Our proposal has been implemented in order to test the protocol procedure and performance. Finally, we compare the protocol with other spontaneous ad hoc network protocols in order to highlight its features and we provide a security analysis of the system. [ABSTRACT FROM PUBLISHER]

A robust group key agreement protocol (GKA) allows a set of players to establish a shared secret key, regardless of network/node failures. Current constant-round GKA protocols are either efficient and nonrobust or robust but not efficient; assuming a reliable broadcast communication medium, the standard encryption-based group key agreement protocol can be robust against arbitrary number of node faults, but the size of the messages broadcast by every player is proportional to the number of players. In contrast, nonrobust group key agreement can be achieved with each player broadcasting just constant-sized messages. We propose a novel 2-round group key agreement protocol, which tolerates up to T node failures, using O(T)-sized messages for any T. We show that the new protocol implies a fully-robust group key agreement with logarithmic-sized messages and expected round complexity close to 2, assuming random node faults. The protocol can be extended to withstand malicious insiders at small constant factor increases in bandwidth and computation. The proposed protocol is secure under the (standard) Decisional Square Diffie-Hellman assumption. [ABSTRACT FROM AUTHOR]