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tacks, confidentiality, non-repudiation, integrity, pri-
vacy, data verification, access control, traceability and
revocability, error detection, liability identification,
flexibility and efficiency despite of timing constraints.
Moreover, VANETs need to be resilient against a se-
ries of attacks including: DoS, malwares, spam, man
in the middle attack, injection of erroneous messages,
cheating with position information, etc.
In fact, cars with selfish behavior and malicious at-
tacks may impact on the expected traffic performance.
For instance, a malicious node can steal frames trans-
mitted from cars or from the infrastructure. A mali-
cious node can also propagate a malicious message to
disturb traffic behavior. Selfish cars can take benefit
of cheating aiming to arrive first. Fortunately, due to
the special characteristics of VANETs and their dy-
namic nature, cheating cars cannot choose which cars
they will interact. Thus, spread lies might become
irrelevant as more participating cars receive recent in-
formation (Lin et al., 2007). However, it is not yet
clear how malicious nodes will influence in intersec-
tion control protocols.
(Lin and Li, 2013) proposed a cooperative authen-
tication scheme for VANETs using a reward approach
implemented by a Trusted Authority (TA). The TA re-
ceives the messages from vehicles when vehicles pass
by the Road Side Units (RSUs), and it sends back new
messages to the vehicles based on their past rewards.
The vehicles obtain a reward as they make contribu-
tion to the network.
A more recent work (Lim and Manivannan, 2016)
presents a protocol for fast dissemination of au-
thenticated messages to propagating phenomena in
VANETs. Phenomena messages are used to prop-
agate accidents, road conditions, etc. RSUs dis-
seminate authenticated messages about the observed
phenomena by vehicles in RSU transmission range.
RSUs are TAs and can verify the authenticity of the
sender and the message integrity before message dis-
semination. Messages sent by vehicles do not require
authentication and verification by other vehicles. The
aim of the protocol is to ensure the anonymity of the
senders and also to allow a mechanism to trace the
messages, when required, for law enforcement agen-
cies, for instance.
Centralized system represents single point of fail-
ures (SPOF) and, therefore, worthwhile targets for at-
tackers. Alternatively, decentralized solutions based
on new technologies can be proposed.
In this direction, blockchain is a promising dis-
tributed architecture to build reliable solutions to In-
telligent Transportation Systems (ITS). In Block-VN
(Sharma et al., 2017), participating entities have dif-
ferent behaviors. Controller nodes provide necessary
services on a large scale communication, miner nodes
deal with communication issues, and other nodes are
just ordinary nodes (vehicles, for instance). Ordinary
nodes send a service request message to other vehi-
cles or for the controller nodes. Using this communi-
cation hierarchy in a distributed way, scalability and
high availability are expected to be achieved. Block-
VN also aims to improve security using trusted inter-
mediary services and by providing distributed, secure,
and shared records of all system actions.
(Leiding et al., 2016) also suggests the application
of blockchain to deal with ITS challenges. Traffic
regulations algorithms can be implemented with the
support of Ethereum high-level languages. Based on
information about cars and traffic conditions, it is pos-
sible to identify and punish misbehaving cars. This
might include high speeding, ignoring traffic lights,
causing an accident, etc. Each car will be identified
by its unique public key. Thus, a punishment can be
imposed to the car (or driver) with such correspond-
ing Ethereum account.
However, the blockchain theory is not yet mature.
Scalability is still a criterion to be more investigated
further. Another important issue is that VANETs are
subject to intense churn (nodes are coming in and out
all the time) and it is not yet known if this behavior
will be efficiently handled by the blockchain technol-
ogy.
3 SECURE TRAFFIC
REGULATION STRATEGY
In this section, we explain the main contribution of
our work using one intersection and a secure way of
data exchange.
3.1 Traffic Regulation Algorithm
The CCC is a TA and communicates with vehicles and
the infrastructure. The used infrastructure is the TL.
The CCC controls the TLs state duration and transi-
tion according to the ratio (rap) between flows. Al-
gorithm 1 represents the used function to regulate the
TL for one intersection. The number of vehicles on
the entrance (E) and the exit (S) of a road for each di-
rection (North, South, East and West) is given in the
following variables: EN, ES, EE, EO, .. ., etc. rap is
computed using the ratio between the vehicle’s num-
ber which is entering to the intersection in a vertical
lane (EN, ES) and the horizontal lane (EE, EO) (see
Figure 3).
The counter shows how long the TL has not
changed its state. GreeenLight (NSALL) and Green-
Preliminary Results for Secure Traffic Regulation
421