Cyber Security Challenges and Solutions for V2X Communications: A Survey

1. Introduction

• IoT connects smart devices that sense their surroundings and share information wirelessly; vehicles joining this network face attacks from authorized and unauthorized nodes.The survey identifies internal attacks as coming from authorized nodes that can bypass authentication, and external attacks as coming from unauthorized nodes.Source: §1 · pp. 2–3

1.1. Relations to Existing Surveys

• Earlier surveys covered general vehicular-network structure or security, or focused on specific mechanisms; this survey examines IEEE 802.11p and LTE-V2X defenses and security-method challenges.The authors aim for the resulting overview to guide future research on vehicular-network challenges.Source: §1.1 · pp. 3–4, §1 · p. 3

1.2. Contributions and Structure

• The paper contributes a security-solutions taxonomy, threat analysis for IEEE 802.11p and LTE-V2X, and evaluation across attacks, message types, latency limits, and model structures.The authors describe their analysis of threats in these technologies as the first of its kind, to their knowledge.Source: §1.2 · p. 4

2. Vehicle-to-Everything (V2X) communication Technology

• V2X connects road entities—including vehicles, pedestrians, cycles, motorcycles, and infrastructure—to share traffic information across the network.The paper associates this connectivity with more accurate traffic information and reports a 2015 dynamic system on Germany’s A9 highway with 35% fewer accidents and 31% fewer people injured (Siemens (2015)).Source: §2 · p. 4

2.1. Architecture

• The heterogeneous ITS architecture separates intra-vehicle sensor networks from inter-vehicle links connecting vehicles with surrounding devices and infrastructure.On-board units process collected data and interact with surrounding entities; roadside units provide local-topology information.Source: §2.1 · pp. 5–6

2.2. Communications

• V2X supports V2S, V2V, V2P, V2G, and V2I links, covering communication among vehicle sensors, vehicles, roadside users, the electric grid, and infrastructure.The communication type depends on the entities establishing the link.Source: §2.2 · p. 6
• Local event messages serve nearby entities over V2V/V2P links with about 100 ms latency, while global event and emergency-vehicle messages address wider-area or road-clearing needs.Periodic beacons report status such as speed, location, and direction at intervals of 100 ms to 1 s, and are described as not time-critical (300 ms).Source: §2.2 · pp. 6–7

2.3. Applications

• ITS applications are grouped into safety, traffic-management, and infotainment uses, including warnings, traffic-data analysis, internet access, and video streaming.Safety applications exchange status and warning messages; traffic applications send collected information to a remote server for analysis.Source: §2.3 · pp. 7–8

3. Security for V2X Enabling Technologies

• IEEE 802.11p has been standardized, implemented, and examined to support safety-related V2X applications.Source: §3 · p. 8
• LTE standardization addresses interoperability among heterogeneous devices and aims to support different V2X communication types through one standard.Release 8 appeared in 2008, and LTE Advanced Pro Release 14 standardization was finalized in early 2017.Source: §3 · p. 8
• Because commuter safety relies on technology performance, the authors argue that the security services of these enabling technologies should be analyzed.Source: §3 · p. 8

3.1.1. Overview

• IEEE 802.11p supports communication between mobile nodes despite obstacles, dynamic topology, and intermittent connections, including V2V and V2I links.It was designed to support non-line-of-sight communication and intelligent-transportation applications.Source: §3.1.1 · p. 8
• IEEE 802.11p is inexpensive to deploy but lacks scalability and QoS, has unlimited delays, and offers only intermittent V2I connectivity because of its short radio range.Source: §3.1.1 · p. 8

3.1.2. Security Measures

• IEEE P1609.2 signs broadcast safety messages with the sender’s certificate and encrypts unicast transaction messages using a symmetric key protected through elliptic-curve encryption.The standard uses ECDSA for signatures; transaction-message keys are random and encrypted with an elliptic curve integrated encryption scheme.Source: §3.1.2 · p. 9

3.2.1. Overview

• LTE-V2X is described as supporting low-latency, high-reliability use cases through components including UEs, eNBs, an application server, and a control function.The control function handles authorization and revocation of V2X services.Source: §3.2.1 · p. 9
• Multimedia broadcast multicast service delivers across multiple cells, while single-cell point-to-multipoint delivers multicast services within one cell.Source: §3.2.1 · pp. 9–10
• LTE-V2X uses cellular links for UE–eNB communication, with uplink to the eNB and downlink from it; the eNB can support one-to-many delivery.Source: §3.2.1 · p. 10
• D2D creates a direct sidelink between UEs, supporting short-range, low-latency and multi-hop communication, including when UEs are outside network coverage.Inband underlay reuses cellular resources but risks collisions; outband uses unlicensed spectrum and requires an extra Wi-Fi Direct or Bluetooth interface.Source: §3.2.1 · p. 11
• An RSU can operate as a stationary UE receiving V2X messages over sidelink, or as an eNB receiving them over the LTE radio interface.In the eNB implementation, the UE's V2X application communicates with the application server in the eNB.Source: §3.2.1 · pp. 11–12

3.2.2. Security Measures

• For cellular communication, UE and core-network mutual authentication generates ciphering and integrity keys, with separate session keys derived for different sessions.Signalling packets use pre-shared symmetric ciphering and integrity algorithms, while user-plane data is ciphered between UE and eNB.Source: §3.2.2 · pp. 12–13
• D2D security depends on network coverage: out-of-coverage UEs use stored authentication vectors or group keys, but shared group integrity keys leave user data without integrity protection.Stored authentication parameters are time-limited and may be revoked; group encryption keys provide confidentiality, but their shared integrity key does not protect user data.Source: §3.2.2 · pp. 13–14

3.3.1. Threats on Availability

• Internal attackers can disrupt availability through blackhole or greyhole forwarding and coordinated attacks; IEEE 802.11p authentication does not prevent internal attackers from joining routes.LTE-V2X can face compromised relays in partial D2D coverage that drop packets and block communication with the eNB.Source: §3.3.1 · pp. 14–16
• Flooding can exploit IEEE 802.11p channel access, LTE-V2X resource scheduling or active-mode transmissions, and forged buffer reports that make an eNB treat a cell as full.Jamming remains unprevented by current solutions for both technologies; directional antennas may reduce its effect or help vehicles avoid the jamming area.Source: §3.3.1 · pp. 15–16

3.3.2. Threats on Integrity

• IEEE 802.11p signatures hinder external false-message injection but do not stop authenticated insiders from signing false safety messages; LTE-V2X likewise leaves user-data integrity unprotected.Replay defenses use message caches in IEEE 802.11p and timestamps, nonces, and short lifetimes in LTE-V2X, while GPS spoofing can undermine location and time checks.Source: §3.3.2 · pp. 16–17

3.3.3. Threats on Confidentiality

• Confidentiality risks include internal eavesdropping, unencrypted messages used to reduce latency and computation costs, and location tracking through identifiable certificates or mappable temporary identifiers.In LTE-V2X, temporary identifiers change continuously but are sent in plaintext; tracking requires mapping identifiers to a UE.Source: §3.3.3 · p. 18

3.3.4. Threats on Authenticity

• Certificate replication, Sybil, and impersonation attacks challenge authenticity; LTE-V2X mutual authentication can reject unauthorized UEs, but out-of-coverage UEs may lack updated revocation lists.Source: §3.3.4 · p. 19

3.3.5. Threats on Non-repudiation

• In cooperative D2D, trust can undermine non-repudiation because a node may communicate with another despite its fake identity.IEEE 802.11p signs periodic and warning messages, while LTE-V2X encrypts UE–eNB exchanges and applies integrity protection to signalling packets.Source: §3.3.5 · pp. 19–20

• Out-of-coverage LTE-V2X D2D is the most exposed protocol because the core network does not manage the link; IEEE 802.11p has more security services for ad-hoc links.Source: §3.4 · p. 20

4. Security Solutions for V2X communications

• The survey classifies security solutions into cryptography-based, behavior-based, and identity-based categories to frame the challenges of V2X security design.The authors present this classification as a basis for studying security models for V2X.Source: §4 · p. 20

4.1. Cryptography-based Solutions

• Cryptography-based solutions use encryption, key management, and authentication to protect communications, with examples addressing privacy, key exchange, and V2X resource and latency constraints.The surveyed approaches include channel-based key generation and cryptographic mix-zones for privacy.Source: §4.1 · pp. 20, 22, 23

4.2. Behavior-based/Trust-based Solutions

• Behavior-based solutions complement cryptography by monitoring node behavior; surveyed approaches include weighted trust, rewards, fuzzy rules, learning, and intrusion detection.Trust may be based on direct monitoring and recommendations from neighboring nodes.Source: §4.2 · pp. 24, 26, 27

4.3. Identity-based Solutions

• Identity-based solutions seek to preserve privacy while retaining trust or accountability, using anonymous identities, pseudonyms, and threshold mechanisms.The surveyed approaches include group IDs and frequently changing pseudonyms.Source: §4.3 · pp. 29–30

4.4. Summary

• The survey concludes that most models use flat networks, often focus on one attack type, and frequently rely on centralized security measures that are unsuitable beyond network coverage.The authors identify out-of-coverage nodes as a boundary for centralized models.Source: §4.4 · p. 31

5. Comparison and Discussion

• Methods are compared by attack coverage, message type, latency limit, and security-model structure.Source: §5 · pp. 31–32

5.1. The considered attacks

• Traditional cryptography can burden distributed networks through key-distribution delay, asymmetric-cryptography latency, and costly group-signature revocation.The survey also notes that most external attacks are already considered by protocol security services, so added cryptography increases network overhead.Source: §5.1 · p. 32
• Behavior-based methods supplement cryptography against legitimate insiders; lightweight weighted sums suit low latency, while rewarding methods target selfish behavior.Fuzzy logic may require training and suits predictable environments; weighted-sum methods face challenges in choosing weights and trust thresholds.Source: §5.1 · p. 32
• Identity-based methods address tracking and false-identity attacks where protocols lack anonymous identities, while hybrid schemes combine checks and signatures for internal and external threats.Examples include plausibility checks for internal attacks and digital signatures for external attacks.Source: §5.1 · pp. 32–33

5.2.1. The event-based messages

• Event messages need not be encrypted when broadcast for rapid local decisions, but sender authentication and behavior-based checks address false alarms, including those from authorized nodes.Encryption can negatively affect network performance; event-based messages are directed to all nodes in an area.Source: §5.2.1 · p. 33

5.2.2. periodic messages

• Periodic beacons expose location, speed, and direction, creating tracking and false-status risks; random identities can be mapped, while synchronized pseudonym changes improve privacy.Beacon-based trust methods assess the validity of beacon messages.Source: §5.2.2 · p. 34

5.3. The latency limit

• Vehicular messages have an approximately 300 ms delivery target; complex trust and machine-learning models can add delay, while pseudonym- and group-ID methods are described as lightweight.Double encryption is cited as increasing computation overhead.Source: §5.3 · pp. 34–35

5.4. The Model structure

• Centralized schemes depend on roadside units that may be unavailable; distributed schemes lack global vehicle history, and a hybrid model reports non-stable detection accuracy.The described hybrid switches to distributed operation when vehicles are outside central-unit coverage.Source: §5.4 · p. 35

6.1. Security attacks

• Trust-based systems remain susceptible to whitewashing, on-off, and good/bad-mouthing attacks; most surveyed works do not address them in vehicular networks.Li et al. (2013) considered intelligent compromised nodes that behave maliciously intermittently.Source: §6.1 · p. 36
• Wireless intra-vehicle networks such as trains, metro systems, and buses are also exposed to cyber-attacks, motivating security models for those subnetworks.Liyanage et al. (2016) proposed a host-identity-protocol-based system against common IP attacks.Source: §6.1 · p. 36
• Centralized solutions relying on trusted RSUs are constrained by roadside coverage and RSU vulnerability, which can impair performance when RSUs are attacked.Hao et al. (2008) developed key-distribution protocols able to detect compromised RSUs and collusion with malicious vehicles.Source: §6.1 · p. 36

6.2. Security vs. QoS management

• V2X must balance security with QoS and device resources because infrastructure and topology are inconsistent and some roadside entities have limited battery capacity.The survey notes that safety warnings require low delay, while encryption can protect confidentiality at a cost to QoS; other proposals consume bandwidth or increase packet size.Source: §6.2 · pp. 36–37
• Existing evaluations omit road settings, realistic propagation and mobility, and malfunction or communication conditions; vehicular edge computing's security and privacy also remain open challenges.Edge computing processes data near its source to reduce transmission delay for latency-sensitive uses such as warning messages.Source: §6.2 · p. 37

7. Conclusion

• The survey clarifies V2X features and architecture, analyzes threats to enabling technologies, and classifies and compares existing vehicular-network security solutions.Source: §7 · p. 38
• It identifies main challenges and future research directions for V2X security.Source: §7 · p. 38
• The paper concludes that combining cryptography and trust strategies will protect networks from internal and external attacks and guarantee a high security level.Source: §7 · p. 38