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Error-correcting codes and matroids have been widely used in the study of ordinary secret sharing schemes. In this paper, the connections between codes, matroids, and a special class of secret sharing schemes, namely, multiplicative linear secret sharing schemes (LSSSs), are studied. Such schemes are known to enable multiparty computation protocols secure(More)
Vehicular ad hoc networks (VANETs) allow vehicleto-vehicle communication and, in particular, vehicle-generated announcements. Provided that the trustworthiness of such announcements can be guaranteed, they can greatly increase the safety of driving. A new system for vehicle-generated announcements is presented that is secure against external and internal(More)
In a threshold broadcast encryption scheme, a sender chooses (ad-hoc) a set of n receivers and a threshold t, and then encrypts a message by using the public keys of all the receivers, in such a way that the original plaintext can be recovered only if at least t receivers cooperate. Previously proposed threshold broadcast encryption schemes have ciphertexts(More)
The fast growth of Radio Frequency IDentification (RFID) implies a deployment challenge, namely how to keep this technology scalable without renouncing security and privacy features. This paper focuses on combining tag privacy and scalability using the hash locks mechanism. Our contribution is twofold: (i) a cell-based architecture is proposed in which the(More)
In a threshold broadcast encryption scheme, a sender chooses (ad-hoc) a set of n receivers and a threshold t, and then encrypts a message by using the public keys of all the receivers, in such a way that the original plaintext can be recovered only if at least t receivers cooperate. This kind of scheme has many applications in mobile ad-hoc networks,(More)
In a threshold signature scheme, a group of players shares some secret information in such a way that only those subsets with a minimum number of players can compute a valid signature. In this paper we propose methods to construct some computationally secure distributed protocols from threshold signature schemes. Namely, we construct metering schemes from(More)
In this paper, we propose some cryptographic techniques to securely set up a mobile ad-hoc network. The process is fully self-managed by the nodes, without any trusted party. New nodes can join the network and are able to obtain the same capabilities as initial nodes; further, each node can obtain a pair of secret/public keys to secure and authenticate its(More)
In this paper we investigate the issues concerning the use of a single server across a network, the key distribution center (KDC) to enable private communications within groups of users. After providing several motivations, showing the advantages related to the distribution of the task accomplished by this server, we describe a model for such a(More)
In [16], Naor, Pinkas and Reingold introduced schemes in which some groups of servers distribute keys among a set of users in a distributed way. They gave some speci c proposals both in the unconditional and in the computational security framework. Their computationally secure scheme is based on the Decisional DiÆe-Hellman Assumption. This model assumes(More)