2 research outputs found
Securing IP Mobility Management for Vehicular Ad Hoc Networks
The proliferation of Intelligent Transportation Systems (ITSs) applications, such as
Internet access and Infotainment, highlights the requirements for improving the underlying
mobility management protocols for Vehicular Ad Hoc Networks (VANETs). Mobility
management protocols in VANETs are envisioned to support mobile nodes (MNs), i.e.,
vehicles, with seamless communications, in which service continuity is guaranteed while
vehicles are roaming through different RoadSide Units (RSUs) with heterogeneous wireless
technologies.
Due to its standardization and widely deployment, IP mobility (also called Mobile IP
(MIP)) is the most popular mobility management protocol used for mobile networks including
VANETs. In addition, because of the diversity of possible applications, the Internet
Engineering Task Force (IETF) issues many MIP's standardizations, such as MIPv6 and
NEMO for global mobility, and Proxy MIP (PMIPv6) for localized mobility. However,
many challenges have been posed for integrating IP mobility with VANETs, including the
vehicle's high speeds, multi-hop communications, scalability, and ef ficiency. From a security
perspective, we observe three main challenges: 1) each vehicle's anonymity and location
privacy, 2) authenticating vehicles in multi-hop communications, and 3) physical-layer
location privacy.
In transmitting mobile IPv6 binding update signaling messages, the mobile node's Home
Address (HoA) and Care-of Address (CoA) are transmitted as plain-text, hence they can
be revealed by other network entities and attackers. The mobile node's HoA and CoA
represent its identity and its current location, respectively, therefore revealing an MN's HoA
means breaking its anonymity while revealing an MN's CoA means breaking its location
privacy. On one hand, some existing anonymity and location privacy schemes require
intensive computations, which means they cannot be used in such time-restricted seamless
communications. On the other hand, some schemes only achieve seamless communication
through low anonymity and location privacy levels. Therefore, the trade-off between the
network performance, on one side, and the MN's anonymity and location privacy, on the
other side, makes preservation of privacy a challenging issue. In addition, for PMIPv6
to provide IP mobility in an infrastructure-connected multi-hop VANET, an MN uses a
relay node (RN) for communicating with its Mobile Access Gateway (MAG). Therefore,
a mutual authentication between the MN and RN is required to thwart authentication
attacks early in such scenarios. Furthermore, for a NEMO-based VANET infrastructure,
which is used in public hotspots installed inside moving vehicles, protecting physical-layer
location privacy is a prerequisite for achieving privacy in upper-layers such as the IP-layer. Due to the open nature of the wireless environment, a physical-layer attacker can easily
localize users by employing signals transmitted from these users.
In this dissertation, we address those security challenges by proposing three security
schemes to be employed for different mobility management scenarios in VANETs, namely,
the MIPv6, PMIPv6, and Network Mobility (NEMO) protocols.
First, for MIPv6 protocol and based on the onion routing and anonymizer, we propose
an anonymous and location privacy-preserving scheme (ALPP) that involves two complementary
sub-schemes: anonymous home binding update (AHBU) and anonymous return
routability (ARR). In addition, anonymous mutual authentication and key establishment
schemes have been proposed, to authenticate a mobile node to its foreign gateway and
create a shared key between them. Unlike existing schemes, ALPP alleviates the tradeoff
between the networking performance and the achieved privacy level. Combining onion
routing and the anonymizer in the ALPP scheme increases the achieved location privacy
level, in which no entity in the network except the mobile node itself can identify this
node's location. Using the entropy model, we show that ALPP achieves a higher degree of
anonymity than that achieved by the mix-based scheme. Compared to existing schemes,
the AHBU and ARR sub-schemes achieve smaller computation overheads and thwart both
internal and external adversaries. Simulation results demonstrate that our sub-schemes
have low control-packets routing delays, and are suitable for seamless communications.
Second, for the multi-hop authentication problem in PMIPv6-based VANET, we propose
EM3A, a novel mutual authentication scheme that guarantees the authenticity of both
MN and RN. EM3A thwarts authentication attacks, including Denial of service (DoS), collusion,
impersonation, replay, and man-in-the-middle attacks. EM3A works in conjunction
with a proposed scheme for key establishment based on symmetric polynomials, to generate
a shared secret key between an MN and an RN. This scheme achieves lower revocation
overhead than that achieved by existing symmetric polynomial-based schemes. For a PMIP
domain with n points of attachment and a symmetric polynomial of degree t, our scheme
achieves t x 2^n-secrecy, whereas the existing symmetric polynomial-based authentication
schemes achieve only t-secrecy. Computation and communication overhead analysis as well
as simulation results show that EM3A achieves low authentication delay and is suitable
for seamless multi-hop IP communications. Furthermore, we present a case study of a
multi-hop authentication PMIP (MA-PMIP) implemented in vehicular networks. EM3A
represents the multi-hop authentication in MA-PMIP to mutually authenticate the roaming
vehicle and its relay vehicle. Compared to other authentication schemes, we show that our
MA-PMIP protocol with EM3A achieves 99.6% and 96.8% reductions in authentication
delay and communication overhead, respectively.
Finally, we consider the physical-layer location privacy attacks in the NEMO-based
VANETs scenario, such as would be presented by a public hotspot installed inside a moving
vehicle. We modify the obfuscation, i.e., concealment, and power variability ideas and
propose a new physical-layer location privacy scheme, the fake point-cluster based scheme,
to prevent attackers from localizing users inside NEMO-based VANET hotspots. Involving
the fake point and cluster based sub-schemes, the proposed scheme can: 1) confuse
the attackers by increasing the estimation errors of their Received Signal Strength (RSSs)
measurements, and 2) prevent attackers' monitoring devices from detecting the user's transmitted
signals. We show that our scheme not only achieves higher location privacy, but
also increases the overall network performance. Employing correctness, accuracy, and certainty
as three different metrics, we analytically measure the location privacy achieved by
our proposed scheme. In addition, using extensive simulations, we demonstrate that the
fake point-cluster based scheme can be practically implemented in high-speed VANETs'
scenarios
The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance
INTRODUCTION
Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic.
RATIONALE
We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs).
RESULTS
Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants.
CONCLUSION
Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century