For people living in urban areas around the world, traffic has unfortunately
become a normal part of daily life. Whether it’s getting to and from
the city itself or traveling within downtown, all kinds of
vehicles—private cars, rideshare services, delivery trucks and even
public buses—clog roadways throughout the day, not just during rush
Round-the-clock congestion makes it harder for people to get where
they’re going and also reduces air quality, making city life harder on
Because traffic is one of the biggest challenges of urban living, it’s
a key focus for many smart city initiatives, and one tool that cities are
using to address the issue is smart road tolling. In city centers, congestion
charges, paid by vehicles entering the city core, limit the number of vehicles
on downtown streets, reduce pollution levels and make the area friendlier to
pedestrians and bicyclists. Electronic road pricing, which adjusts the toll
according to traffic level, uses peak pricing during heavy travel times to
encourage the use of alternate routes and alternative modes of transportation
thereby reducing congestion.
Smart road tolling can also take the form of upgrading traditional tolling
systems so they work more efficiently. Road tolls have always been an
important source of revenue for transport agencies since they help pay for
maintenance and new construction, but traditional toll-collection methods,
which involve stop-and-go plazas, inevitably lead to long lines of cars.
A system for automated toll collection lets vehicles pay tolls without having
to stop or even slow down and, as a result, helps keep traffic flowing
smoothly, with lower pollution levels and a lot less driver frustration. As
one of the various ways to implement automated toll collection, secure passive
long range RFID (also called RAIN RFID) offers a particularly compelling
combination of security and convenience.
When compared to the other two formats most frequently used for automated toll
collection—optical and active RFID—the advantages of secure
passive RFID become clear.
Optical Toll Collection
A camera is used to read the license plate. Software is then used to extract
the plate number and identify the driver so the tolling agency can send a
bill. The positive is that the system works with any car carrying a license
plate, but the negative is that the system isn’t always right. Humans
typically have to check and confirm the readings and the high degree of manual
post-processing is inefficient and costly.
Optical systems need a high level of human supervision
Active RFID Toll Collection
Vehicle owners buy and install an active RFID transponder, which then
interacts with readers mounted at toll plazas. RFID transponders are more
accurate than optical systems, so there’s little, if any manual
post-processing required, but the equipment tends to be expensive, bulky, hard
to moun and has a limited lifetime because the transponder needs a battery to
Active RFID delivers accuracy but at a high cost to drivers
A Better Way—Road Tolling with Secure Passive RAIN (or Long Range) RFID
With secure passive RFID, toll machines read a tag placed somewhere on the
vehicle, such as the license plate, the bumper, inside the windshield or on a
motorcycle’s headlamp. The tag can be issued in a sticker format so
it’s easy to install. The tag doesn’t contain a battery (it
draws power from the reader’s antenna), so it’s relatively
inexpensive to produce and doesn’t require upkeep. The tag also works
even in harsh weather conditions and perhaps even more importantly, uses
encryption to ensure the security and privacy of tag data.
A smart toll-collection system based on secure passive RAIN RFID overcomes the
drawbacks of using optical or active RFID. The setup operates automatically
without human intervention, is accurate yet inexpensive to implement and uses
cryptographic authentication to ensure security and privacy. It also improves
tolling by adding new levels of performance and flexibility.
With secure passive RFID, toll paying is accurate, inexpensive and protected
Protecting Privacy While Ensuring Traffic Flow
Security is an essential aspect of the setup because the toll-collection
system has to process sensitive information, such as the name of the
registered car owner and the payment card details associated with the
registration. The latest passive RFID tags and especially those based on RAIN
RFID (UHF) technology are equipped with special security mechanisms that help
ensure that information stored on the tag remains protected from unauthorized
IC is based on RAIN RFID technology and designed for this kind of protection.
Embedded in a tag for road tolling use cases, it offers security features such
as tag authentication, so only an authorized RFID reader can access tag data.
The toll-payment transaction involves two electronic devices, the tag and the
reader. Both parts of the equation need to be secure, so it’s not
enough for the tag to have built-in security features. For the authentication
process to remain trustworthy, the reader has to be equipped with security
mechanisms, too. A convenient way to provide maximum security inside the
reader is to add a dedicated secure platform, called a secure application
module (SAM) inside the reader.
The SAM increases security by storing and processing system access keys and
enabling encrypted communication. The SAM is a purpose-built IC that delivers
very high levels of security, privacy and speed. The standard microcontroller
memories and software implementations, based on crypto algorithms, typically
can’t match the level of protection provided by a SAM.
MIFARE SAM AV3, for example, is a dedicated, performance-optimized IC and a core element
for a secure reader/writer system. Along with securely storing keys inside the
RFID reader, the MIFARE SAM AV3 computes unique session keys, uses AES-128
encryption to protect the message and enables secure access and communication
with the UCODE DNA tag IC. Upon reception of private data from the RAIN RFID
tag, the MIFARE SAM AV3 handles the decryption and processing of the incoming
message. Because the MIFARE SAM AV3 is designed to work with the UCODE DNA IC,
it simplifies the implementation in a secure reader system and reduces
time to market for the design.
The block diagram shows how the MIFARE SAM AV3 and UCODE DNA IC work
together in a system.
A UCODE DNA IC is embedded in the tag/label the driver attaches to their
windshield or license plate. The MIFARE SAM AV3 is mounted into a slot on the
reader terminal at the toll station where it helps to protect keys and enable
secure transactions. As part of its role in tag authentication and other
privacy use cases, the MIFARE SAM AV3 can store the leader keys used to
generate tag-specific UCODE DNA keys (called “derived keys”).
One advantage of the UCODE DNA and MIFARE SAM AV3 combination is that road
tolling functions can happen offline, without depending on online systems. The
combination also supports the introduction of new use cases, since the UCODE
DNA tag on a vehicle also supports broader smart city programs. For instance,
it can be used for other automatic vehicle identification (AVI) applications,
such as access control, to let certain vehicles enter restricted areas like
parking spaces and for speed control, to issue citations. The UCODE DNA tag
can act as an authentic credential for micropayments so you can pay for gas or
access a paid parking garage without reaching for your wallet. The UCODE DNA
tag can also be used to track loyalty points at gas station shops as part of a
reward system for frequent purchases.
Our next blog will focus on public transport, with a description of how the
MIFARE SAM AV3 protects automated fare collection (AFC) systems and other
transport ticketing use cases.
For more on NXP’s solutions for smart, secure road tolling, we suggest
the following resources:
Product Manager for Dual Interface Smart Card ICs, NXP
Michael Ganzera, marketing manager for MIFARE SAM (Secure
Application Modules), joined NXP in 2001 as product manager for
dual interface smart card ICs before he took over the
responsibility for eGovernment marketing in 2004. Jointly with
his team he supported the role of NXP to become a trusted
supplier for e-Passport projects globally. Michael has around 20
years of experience in contactless identifcation solutions and
devotes his free time to outdoor sports such as mountain biking.