9,248 research outputs found

    Trust-based security for the OLSR routing protocol

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    International audienceThe trust is always present implicitly in the protocols based on cooperation, in particular, between the entities involved in routing operations in Ad hoc networks. Indeed, as the wireless range of such nodes is limited, the nodes mutually cooperate with their neighbors in order to extend the remote nodes and the entire network. In our work, we are interested by trust as security solution for OLSR protocol. This approach fits particularly with characteristics of ad hoc networks. Moreover, the explicit trust management allows entities to reason with and about trust, and to take decisions regarding other entities. In this paper, we detail the techniques and the contributions in trust-based security in OLSR. We present trust-based analysis of the OLSR protocol using trust specification language, and we show how trust-based reasoning can allow each node to evaluate the behavior of the other nodes. After the detection of misbehaving nodes, we propose solutions of prevention and countermeasures to resolve the situations of inconsistency, and counter the malicious nodes. We demonstrate the effectiveness of our solution taking different simulated attacks scenarios. Our approach brings few modifications and is still compatible with the bare OLSR

    Provable Security of Substitution-Permutation Networks

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    Many modern block ciphers are constructed based on the paradigm of substitution-permutation networks (SPNs). But, somewhat surprisingly---especially in comparison with Feistel networks, which have been analyzed by dozens of papers going back to the seminal work of Luby and Rackoff---there are essentially no provable-security results about SPNs. In this work, we initiate a comprehensive study of the security of SPNs as strong pseudorandom permutations when the underlying SS-box is modeled as a public random permutation. We show that 3~rounds of S-boxes are necessary and sufficient for secure linear SPNs, but that even 1-round SPNs can be secure when non-linearity is allowed. Additionally, our results imply security in settings where an SPN structure is used for domain extension of a block cipher, even when the attacker has direct access to the small-domain block cipher

    Обчислення верхніх меж диференціальних імовірностей для деяких класів блочних шифрів

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    Пропонується метод обчислення верхніх меж диференціальних імовірностей для класу немарковських схем Фейстеля, що дозволяє встановити теоретичну стійкість шифрів даного класу до диференціального криптоаналізу.We propose a new technique for estimating upper bounds of differential probabilities for class of non-Markov Feistel networks. These results allow to claim provable security against differential cryptanalysis for ciphers from this class
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