![](bg8.png)
certificate, described in the previous Section 3.3. We
do not show the code here, but we remind the readers
that it is publicly available online.
4.3 Security Properties
In Tamarin, security properties are defined as 1st-
order logic formulas, which we use to define the prop-
erties that must be true in order to guarantee ”end-
to-end security” for the communications protected by
OSCORE: (i) The OSCORE master secret actually
remains secret (from the point of view of the adver-
sary) during the certificate enrollment process and the
establishment of the Security Context. (ii) The mes-
sages between services and end-devices are secret, i.e.
no one except the destination of a message can de-
crypt its payload. (iii) The messages between services
and end-devices are authenticated, i.e. both the ser-
vice and the device are certain they talk to each other,
and replay-protected, i.e. an adversary cannot record
an encrypted message and send it a second time to
trick its recipient. Altogether, it ensures that a de-
vice can establish a secure end-to-end channel with
a service and that they can communicate safely even
through an untrusted C-ITS network. No man-in-the-
middle can spy on their communication or imperson-
ate them, and no replay attack is possible.
5 CONCLUSION
In this paper, we present a solution, compatible with
the C-ITS automotive standards and entirely based
on standardized (or soon-to-be standardized) open-
source protocols, to get end-to-end security between
a resource-constrained IoT device and a distant back-
end server, including through an un-trusted vehic-
ular network. It leverages the newly standardized
OSCORE protocol as an application-layer encryption
mechanism to secure a payload even through relays
and proxy forwarding, and it covers the whole life-
cycle of a device, from the original Certificate Enroll-
ment to the communication between service and end-
device through the initial OSCORE Security Context
establishment. Further, we analyzed our solution us-
ing the Tamarin Prover, a well-known and reputable
security analysis tool, and guarantee that our specifi-
cations provide authenticity and secrecy even against
an adversary in full control of the network.
ACKNOWLEDGMENT
This research has partly been funded by the H2020
ECSEL SECREDAS (Grant ID: 783119) and partly
by the H2020 CONCORDIA (Grant ID: 830927).
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