44,213 research outputs found
Lattice-Based Group Signatures: Achieving Full Dynamicity (and Deniability) with Ease
In this work, we provide the first lattice-based group signature that offers
full dynamicity (i.e., users have the flexibility in joining and leaving the
group), and thus, resolve a prominent open problem posed by previous works.
Moreover, we achieve this non-trivial feat in a relatively simple manner.
Starting with Libert et al.'s fully static construction (Eurocrypt 2016) -
which is arguably the most efficient lattice-based group signature to date, we
introduce simple-but-insightful tweaks that allow to upgrade it directly into
the fully dynamic setting. More startlingly, our scheme even produces slightly
shorter signatures than the former, thanks to an adaptation of a technique
proposed by Ling et al. (PKC 2013), allowing to prove inequalities in
zero-knowledge. Our design approach consists of upgrading Libert et al.'s
static construction (EUROCRYPT 2016) - which is arguably the most efficient
lattice-based group signature to date - into the fully dynamic setting.
Somewhat surprisingly, our scheme produces slightly shorter signatures than the
former, thanks to a new technique for proving inequality in zero-knowledge
without relying on any inequality check. The scheme satisfies the strong
security requirements of Bootle et al.'s model (ACNS 2016), under the Short
Integer Solution (SIS) and the Learning With Errors (LWE) assumptions.
Furthermore, we demonstrate how to equip the obtained group signature scheme
with the deniability functionality in a simple way. This attractive
functionality, put forward by Ishida et al. (CANS 2016), enables the tracing
authority to provide an evidence that a given user is not the owner of a
signature in question. In the process, we design a zero-knowledge protocol for
proving that a given LWE ciphertext does not decrypt to a particular message
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
An Identity-Based Group Signature with Membership Revocation in the Standard Model
Group signatures allow group members to sign an arbitrary number\ud
of messages on behalf of the group without revealing their\ud
identity. Under certain circumstances the group manager holding a\ud
tracing key can reveal the identity of the signer from the\ud
signature. Practical group signature schemes should support\ud
membership revocation where the revoked member loses the\ud
capability to sign a message on behalf of the group without\ud
influencing the other non-revoked members. A model known as\ud
\emph{verifier-local revocation} supports membership revocation.\ud
In this model the trusted revocation authority sends revocation\ud
messages to the verifiers and there is no need for the trusted\ud
revocation authority to contact non-revoked members to update\ud
their secret keys. Previous constructions of verifier-local\ud
revocation group signature schemes either have a security proof in the\ud
random oracle model or are non-identity based. A security proof\ud
in the random oracle model is only a heuristic proof and\ud
non-identity-based group signature suffer from standard Public Key\ud
Infrastructure (PKI) problems, i.e. the group public key is not\ud
derived from the group identity and therefore has to be certified.\ud
\ud
\ud
In this work we construct the first verifier-local revocation group\ud
signature scheme which is identity-based and which has a security proof in the standard model. In\ud
particular, we give a formal security model for the proposed\ud
scheme and prove that the scheme has the\ud
property of selfless-anonymity under the decision Linear (DLIN)\ud
assumption and it is fully-traceable under the\ud
Computation Diffie-Hellman (CDH) assumption. The proposed scheme is based on prime order bilinear\ud
groups
A comprehensive meta-analysis of cryptographic security mechanisms for cloud computing
The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.The concept of cloud computing offers measurable computational or information resources as a service over the Internet. The major motivation behind the cloud setup is economic benefits, because it assures the reduction in expenditure for operational and infrastructural purposes. To transform it into a reality there are some impediments and hurdles which are required to be tackled, most profound of which are security, privacy and reliability issues. As the user data is revealed to the cloud, it departs the protection-sphere of the data owner. However, this brings partly new security and privacy concerns. This work focuses on these issues related to various cloud services and deployment models by spotlighting their major challenges. While the classical cryptography is an ancient discipline, modern cryptography, which has been mostly developed in the last few decades, is the subject of study which needs to be implemented so as to ensure strong security and privacy mechanisms in todayās real-world scenarios. The technological solutions, short and long term research goals of the cloud security will be described and addressed using various classical cryptographic mechanisms as well as modern ones. This work explores the new directions in cloud computing security, while highlighting the correct selection of these fundamental technologies from cryptographic point of view
KeyForge: Mitigating Email Breaches with Forward-Forgeable Signatures
Email breaches are commonplace, and they expose a wealth of personal,
business, and political data that may have devastating consequences. The
current email system allows any attacker who gains access to your email to
prove the authenticity of the stolen messages to third parties -- a property
arising from a necessary anti-spam / anti-spoofing protocol called DKIM. This
exacerbates the problem of email breaches by greatly increasing the potential
for attackers to damage the users' reputation, blackmail them, or sell the
stolen information to third parties.
In this paper, we introduce "non-attributable email", which guarantees that a
wide class of adversaries are unable to convince any third party of the
authenticity of stolen emails. We formally define non-attributability, and
present two practical system proposals -- KeyForge and TimeForge -- that
provably achieve non-attributability while maintaining the important protection
against spam and spoofing that is currently provided by DKIM. Moreover, we
implement KeyForge and demonstrate that that scheme is practical, achieving
competitive verification and signing speed while also requiring 42% less
bandwidth per email than RSA2048
SECMACE: Scalable and Robust Identity and Credential Management Infrastructure in Vehicular Communication Systems
Several years of academic and industrial research efforts have converged to a
common understanding on fundamental security building blocks for the upcoming
Vehicular Communication (VC) systems. There is a growing consensus towards
deploying a special-purpose identity and credential management infrastructure,
i.e., a Vehicular Public-Key Infrastructure (VPKI), enabling pseudonymous
authentication, with standardization efforts towards that direction. In spite
of the progress made by standardization bodies (IEEE 1609.2 and ETSI) and
harmonization efforts (Car2Car Communication Consortium (C2C-CC)), significant
questions remain unanswered towards deploying a VPKI. Deep understanding of the
VPKI, a central building block of secure and privacy-preserving VC systems, is
still lacking. This paper contributes to the closing of this gap. We present
SECMACE, a VPKI system, which is compatible with the IEEE 1609.2 and ETSI
standards specifications. We provide a detailed description of our
state-of-the-art VPKI that improves upon existing proposals in terms of
security and privacy protection, and efficiency. SECMACE facilitates
multi-domain operations in the VC systems and enhances user privacy, notably
preventing linking pseudonyms based on timing information and offering
increased protection even against honest-but-curious VPKI entities. We propose
multiple policies for the vehicle-VPKI interactions, based on which and two
large-scale mobility trace datasets, we evaluate the full-blown implementation
of SECMACE. With very little attention on the VPKI performance thus far, our
results reveal that modest computing resources can support a large area of
vehicles with very low delays and the most promising policy in terms of privacy
protection can be supported with moderate overhead.Comment: 14 pages, 9 figures, 10 tables, IEEE Transactions on Intelligent
Transportation System
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