78,411 research outputs found
An efficient certificateless authenticated key agreement protocol without bilinear pairings
Certificateless public key cryptography simplifies the complex certificate
management in the traditional public key cryptography and resolves the key
escrow problem in identity-based cryptography. Many certificateless
authenticated key agreement protocols using bilinear pairings have been
proposed. But the relative computation cost of the pairing is approximately
twenty times higher than that of the scalar multiplication over elliptic curve
group. Recently, several certificateless authenticated key agreement protocols
without pairings were proposed to improve the performance. In this paper, we
propose a new certificateless authenticated key agreement protocol without
pairing. The user in our just needs to compute five scale multiplication to
finish the key agreement. We also show the proposed protocol is secure in the
random oracle model
Strengths and Weaknesses of Near Field Communication (NFC) Technology
This paper gives a comprehensive analysis of security with respect to NFC. We propose a
protocol that can be used between an RFID tag and a reader to exchange a secret without
performing any expensive computation. The paper introduced an NFC specific key agreement
mechanism, which provides cheap and fast secure key agreement. Key agreement techniques
without authentication can be used to provide a standard secure channel. This resistance against
Man-in-the-Middle attacks makes NFC an ideal method for secure pairing of devices. The paper
lists some of threats, which are applicable to NFC, and describes solutions to protect against these threats
On the Security of an Efficient Group Key Agreement Scheme for MANETs
Yang et al. have proposed an efficient group key agreement scheme for
Mobile Adhoc Networks. The scheme is efficient as only one bilinear
computation is required for group members to obtain the session key. The scheme is analyzed for security without random oracle model. However, we prove that their scheme is not secure. In particular, we show that any passive adversary (or non-group member) can compute the
session key without having access to the individual secret keys of the group members. Hence, Yang et al. scheme cannot be used for secure group communication. We also show that, the scheme cannot be used for
secure group communication unless there exists a central entity, and hence cannot be used for secure communication in mobile adhoc networks
On the Power of an Honest Majority in Three-Party Computation Without Broadcast
Fully secure multiparty computation (MPC) allows a set of parties to compute some function of their inputs, while guaranteeing correctness, privacy, fairness, and output delivery. Understanding the necessary and sufficient assumptions that allow for fully secure MPC is an important goal. Cleve (STOC\u2786) showed that full security cannot be obtained in general without an honest majority. Conversely, by Rabin and Ben-Or (STOC\u2789), assuming a broadcast channel and an honest majority enables a fully secure computation of any function.
Our goal is to characterize the set of functionalities that can be computed with full security, assuming an honest majority, but no broadcast. This question was fully answered by Cohen et al. (TCC\u2716) -- for the restricted class of symmetric functionalities (where all parties receive the same output). Instructively, their results crucially rely on agreement and do not carry over to general asymmetric functionalities. In this work, we focus on the case of three-party asymmetric functionalities, providing a variety of necessary and sufficient conditions to enable fully secure computation.
An interesting use-case of our results is server-aided computation, where an untrusted server helps two parties to carry out their computation. We show that without a broadcast assumption, the resource of an external non-colluding server provides no additional power. Namely, a functionality can be computed with the help of the server if and only if it can be computed without it. For fair coin tossing, we further show that the optimal bias for three-party (server-aided) -round protocol remains (as in the two-party setting)
Secure two-party computation in applied pi-calculus:models and verification
Secure two-party computation allows two mutually distrusting parties to compute a function together, without revealing their secret inputs to each other. Traditionally, the security properties desired in this context, and the corresponding security proofs, are based on a notion of simulation, which can be symbolic or computational. Either way, the proofs of security are intricate, requiring first to find a simulator, and then to prove a notion of indistinguishability. Furthermore, even for classic protocols such as Yao’s (based on garbled circuits and oblivious transfer), we do not have adequate symbolic models for cryptographic primitives and protocol roles, that can form the basis for automated security proofs. We therefore propose new models in applied pi-calculus in order to address these gaps. Our contributions, formulated in the context of Yao’s protocol, include: an equational theory for specifying the primitives of garbled computation and oblivious trans-fer; process specifications for the roles of the two parties in Yao’s protocol; definitions of security that are more clear and direct: result integrity, input agreement (both based on correspondence assertions) and input privacy (based on observational equivalence). We put these models together and illustrate their use with ProVerif, providing a first automated verification of security for Yao’s two-party computation protocol.
Peer-to-Peer Secure Multi-Party Numerical Computation Facing Malicious Adversaries
We propose an efficient framework for enabling secure multi-party numerical
computations in a Peer-to-Peer network. This problem arises in a range of
applications such as collaborative filtering, distributed computation of trust
and reputation, monitoring and other tasks, where the computing nodes is
expected to preserve the privacy of their inputs while performing a joint
computation of a certain function. Although there is a rich literature in the
field of distributed systems security concerning secure multi-party
computation, in practice it is hard to deploy those methods in very large scale
Peer-to-Peer networks. In this work, we try to bridge the gap between
theoretical algorithms in the security domain, and a practical Peer-to-Peer
deployment.
We consider two security models. The first is the semi-honest model where
peers correctly follow the protocol, but try to reveal private information. We
provide three possible schemes for secure multi-party numerical computation for
this model and identify a single light-weight scheme which outperforms the
others. Using extensive simulation results over real Internet topologies, we
demonstrate that our scheme is scalable to very large networks, with up to
millions of nodes. The second model we consider is the malicious peers model,
where peers can behave arbitrarily, deliberately trying to affect the results
of the computation as well as compromising the privacy of other peers. For this
model we provide a fourth scheme to defend the execution of the computation
against the malicious peers. The proposed scheme has a higher complexity
relative to the semi-honest model. Overall, we provide the Peer-to-Peer network
designer a set of tools to choose from, based on the desired level of security.Comment: Submitted to Peer-to-Peer Networking and Applications Journal (PPNA)
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Toward an RSU-unavailable lightweight certificateless key agreement scheme for VANETs
Vehicle ad-hoc networks have developed rapidly these years, whose security and privacy issues are always concerned widely. In spite of a remarkable research on their security solutions, but in which there still lacks considerations on how to secure vehicle-to-vehicle communications, particularly when infrastructure is unavailable. In this paper, we propose a lightweight certificateless and one-round key agreement scheme without pairing, and further prove the security of the proposed scheme in the random oracle model. The proposed scheme is expected to not only resist known attacks with less computation cost, but also as an efficient way to relieve the workload of vehicle-to-vehicle authentication, especially in no available infrastructure circumstance. A comprehensive evaluation, including security analysis, efficiency analysis and simulation evaluation, is presented to confirm the security and feasibility of the proposed scheme
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