470 research outputs found
A Thesis: A CRYPTOGRAPHIC STUDY OF SOME DIGITAL SIGNATURE SCHEMES.
In this thesis, we propose some directed signature schemes. In addition, we have discussed their applications in different situations. In this thesis, we would like to discuss the security aspects during the design process of the proposed directed digital signature schemes. The security of the most digital signature schemes widely use in practice is based on the two difficult problems, viz; the problem of factoring integers (The RSA scheme) and the problem of finding discrete logarithms over finite fields (The ElGamal scheme).
The proposed works in this thesis is divided into seven chapters
Security and Privacy Issues in Wireless Mesh Networks: A Survey
This book chapter identifies various security threats in wireless mesh
network (WMN). Keeping in mind the critical requirement of security and user
privacy in WMNs, this chapter provides a comprehensive overview of various
possible attacks on different layers of the communication protocol stack for
WMNs and their corresponding defense mechanisms. First, it identifies the
security vulnerabilities in the physical, link, network, transport, application
layers. Furthermore, various possible attacks on the key management protocols,
user authentication and access control protocols, and user privacy preservation
protocols are presented. After enumerating various possible attacks, the
chapter provides a detailed discussion on various existing security mechanisms
and protocols to defend against and wherever possible prevent the possible
attacks. Comparative analyses are also presented on the security schemes with
regards to the cryptographic schemes used, key management strategies deployed,
use of any trusted third party, computation and communication overhead involved
etc. The chapter then presents a brief discussion on various trust management
approaches for WMNs since trust and reputation-based schemes are increasingly
becoming popular for enforcing security in wireless networks. A number of open
problems in security and privacy issues for WMNs are subsequently discussed
before the chapter is finally concluded.Comment: 62 pages, 12 figures, 6 tables. This chapter is an extension of the
author's previous submission in arXiv submission: arXiv:1102.1226. There are
some text overlaps with the previous submissio
Identity-based threshold group signature scheme based on multiple hard number theoretic problems
We introduce in this paper a new identity-based threshold signature (IBTHS) technique, which is based on a pair of intractable problems, residuosity and discrete logarithm. This technique relies on two difficult problems and offers an improved level of security relative to an individual hard problem. The majority of the denoted IBTHS techniques are established on an individual difficult problem. Despite the fact that these methods are secure, however, a prospective solution of this sole problem by an adversary will enable him/her to recover the entire private data together with secret keys and configuration values of the associated scheme. Our technique is immune to the four most familiar attack types in relation to the signature schemes. Enhanced performance of our proposed technique is verified in terms of minimum cost of computations required by both of the signing algorithm and the verifying algorithm in addition to immunity to attacks
An Efficient and Provably Secure ID-Based Threshold Signcryption Scheme
Signcryption is a cryptographic primitive that performs digital
signature and public key encryption simultaneously, at a lower
computational costs and communication overheads than the
signature-then-encryption approach. Recently, two identity-based
threshold signcryption schemes[12],[26] have been
proposed by combining the concepts of identity-based threshold
signature and signcryption together. However, the formal models and
security proofs for both schemes are not considered. In this paper,
we formalize the concept of identity-based threshold signcryption
and give a new scheme based on the bilinear pairings. We prove its
confidentiality under the Decisional Bilinear Diffie-Hellman
assumption and its unforgeability under the Computational
Diffie-Hellman assumption in the random oracle model. Our scheme
turns out to be more efficient than the two previously proposed
schemes
EFFICIENT AND SCALABLE NETWORK SECURITY PROTOCOLS BASED ON LFSR SEQUENCES
The gap between abstract, mathematics-oriented research in cryptography and the engineering approach of designing practical, network security protocols is widening. Network researchers experiment with well-known cryptographic protocols suitable for different network models. On the other hand, researchers inclined toward theory often design cryptographic schemes without considering the practical network constraints. The goal of this dissertation is to address problems in these two challenging areas: building bridges between practical network security protocols and theoretical cryptography. This dissertation presents techniques for building performance sensitive security protocols, using primitives from linear feedback register sequences (LFSR) sequences, for a variety of challenging networking applications. The significant contributions of this thesis are:
1. A common problem faced by large-scale multicast applications, like real-time news feeds, is collecting authenticated feedback from the intended recipients. We design an efficient, scalable, and fault-tolerant technique for combining multiple signed acknowledgments into a single compact one and observe that most signatures (based on the discrete logarithm problem) used in previous protocols do not result in a scalable solution to the problem.
2. We propose a technique to authenticate on-demand source routing protocols in resource-constrained wireless mobile ad-hoc networks. We develop a single-round multisignature that requires no prior cooperation among nodes to construct the multisignature and supports authentication of cached routes.
3. We propose an efficient and scalable aggregate signature, tailored for applications like building efficient certificate chains, authenticating distributed and adaptive content management systems and securing path-vector routing protocols.
4. We observe that blind signatures could form critical building blocks of privacypreserving accountability systems, where an authority needs to vouch for the legitimacy of a message but the ownership of the message should be kept secret from the authority. We propose an efficient blind signature that can serve as a protocol building block for performance sensitive, accountability systems.
All special forms digital signaturesāaggregate, multi-, and blind signaturesāproposed in this dissertation are the first to be constructed using LFSR sequences. Our detailed cost analysis shows that for a desired level of security, the proposed signatures outperformed existing protocols in computation cost, number of communication rounds and storage overhead
Adding Query Privacy to Robust DHTs
Interest in anonymous communication over distributed hash tables (DHTs) has
increased in recent years. However, almost all known solutions solely aim at
achieving sender or requestor anonymity in DHT queries. In many application
scenarios, it is crucial that the queried key remains secret from intermediate
peers that (help to) route the queries towards their destinations. In this
paper, we satisfy this requirement by presenting an approach for providing
privacy for the keys in DHT queries.
We use the concept of oblivious transfer (OT) in communication over DHTs to
preserve query privacy without compromising spam resistance. Although our
OT-based approach can work over any DHT, we concentrate on communication over
robust DHTs that can tolerate Byzantine faults and resist spam. We choose the
best-known robust DHT construction, and employ an efficient OT protocol
well-suited for achieving our goal of obtaining query privacy over robust DHTs.
Finally, we compare the performance of our privacy-preserving protocols with
their more privacy-invasive counterparts. We observe that there is no increase
in the message complexity and only a small overhead in the computational
complexity.Comment: To appear at ACM ASIACCS 201
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