International Core Journal of Engineering 2020-26 | Page 179

in its perfect hybrid encryption authentication
mechanism and diversified network access mode,
which can adapt to different IoT scenarios.
IPsec VPN is an industry-standard network security
protocol. IPsec can protect the information exchanged
between sites with confidentiality and integrity, and support
authentication to effectively defend against network attacks.
IPsec can provide transparent security services for IP
network communication [13] and protect against TCP attacks
by protecting TCP/IP communications from eavesdropping
and tampering. It provides identity authentication, data
integrity checking, and confidentiality mechanisms for data
sources to protect against data attacks. At the same time,
IPsec is also a complete network security solution that is
easy to expand. To ensure the security of data transmission,
IPSec VPN usually uses SHA1, MD5, DES, AES and other
algorithms to authenticate and encrypt data to ensure the
integrity, confidentiality and availability of network data
transmission. China Cryptography Authority introduced the
technical specification of IPsec VPN in 2010 [14], which
stipulates that the symmetric algorithm uses SM1/SM4, the
asymmetric algorithm uses SM2, and the digest algorithm
uses SM3.
x The experimental results show that the gateway can
meet the communication rate requirements and
security requirements in the IoT environment, and can
conduct diverse access, with low power consumption
and strong stability.
II. R ELATED T ECGNICAL O VERVIEW
A. PUF Technology
PUF [9] can be uniquely identified by its inherent
physical structure and has evolved into one of the important
technologies in the field of hardware security. The challenge
response pair (CRP) is an important concept in PUF. The
PUF circuit can generate a stable set of CRPs. For a specific
PUF chip, CRPs can remain stable even if external
conditions (such as voltage, temperature, etc.) change to
some extent. At the same time, due to the physical
randomness caused by the process deviation between the
internal logic gate and the wiring during the manufacturing
process of the chip, even if the circuit design is the same,
each chip has a unique corresponding feature quantity, and
the feature quantity cannot be copied. So it can be immune to
invasive attacks [10].
III. S ECURITY M ECHANISM D ESIGN
A. Perceptual Layer Security Mechanism Design
Due to the self-organizing nature of wireless sensor
networks, nodes located at the sensing layer are vulnerable to
different forms of attacks, such as passive listening networks,
topology detection, and active blocking, collision, and
spoofing. IoT protocol itself lacks perfect security
mechanisms. For example, the MQTT V3.1 protocol
specification does not define any security management
scheme for MQTT communication [15]. The ZigBee
protocol follows the IEEE802.15.4 standard and inherently
inherits some security risks[16]. The Bluetooth V4.0
specification also faces security threats such as
eavesdropping, tampering, and replay, and is not resistant to
replication attacks[17]. At the same time, as a limited device,
the terminal node of the Internet of Things is difficult to copy
the security solution for the Internet. If the pre-shared key is
used, when the chip is lost, it is vulnerable to copying attacks
and reverse engineering cracking. The key is cracked,
creating a huge security risk. The attacker can forge the node
to communicate with the coordinator. If the digital certificate
is used, it needs multiplied operation, and its calculation
amount is relatively large for the sensor node. Although the
method of using the two-line pair authentication reduces the
resource overhead to a certain extent, it is still relatively
unsuitable for deployment in resource-sensitive sensing
nodes.
The sensing node equipped with the PUF circuit is
unforgeable. After obtaining a stable set of CRPs, the output
port of the PUF circuit will be blown, making it impossible
for an attacker to copy the node carrying the PUF circuit.
Thereby it solves the problem of illegal intrusion and
spoofing attacks on nodes. In the authentication process, the
PUF circuit generates a corresponding session key, which
can effectively avoid the drawbacks of the key being stolen
after the key is stored in the non-volatile memory in the
traditional encryption mechanism, and can effectively resist
the spoofing attack.[11-12]
B. VPN Technology
Virtual private network (VPN) is a logical network built
on the public network Internet. A virtual private tunnel is
established between two gateway devices for data
transmission. Because of its advantages in network flexibility,
security, economy, and scalability, it has become the best
choice for building a remote secure access network. From the
perspective of access methods, VPN technology is mainly
divided into site-to-site connection mode and remote access
connection mode. Site-to-site VPN technologies include
Generic Routing Encapsulation(GRE), Internet Protocol
Security(IPSec) and Multi-Protocol Label Switching(MPLS).
The data of the GRE VPN and the MPLS VPN are
transmitted in plain text, and security risks such as illegal
access and internal attacks cannot be avoided. Remote access
VPN technology includes IPSec, Virtual Private Dialˉup
Networks(VPDN) and Secure Sockets Layer(SSL). In these
modes, VPDN is a relatively traditional technology, and SSL
is used to encrypt HTTP data streams. But SSL does not
provide non-repudiation protection. As a comprehensive
technology, IPSec is not only suitable for site-to-site VPN
connections, but also for remote access VPN. Therefore,
IPsec VPN technology is used to implement secure
communication between the gateway and the server.
Secure communication is divided into three phases. Phase
1 completes the identity authentication and status
discrimination for both parties. Phase 2 completes the
negotiation of the session key by exchanging the encrypted
Nonce value, and Phase 3 uses the negotiated session key for
the confidential message transmission. Specific steps are as
follows:
Step 1: The node and the coordinator join the sensing
network and establish initial communication, and both
parties publish their own identity in the WSN.
Step 2: The coordinator sends a specific incentive to the
node according to the identity issued in the WSN, and the
incentive is selected from the stored CRPs. The response of
the incentive is taken out from the database, which is defined
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