Securing LAN Communications with Blockchain-Inspired Mechanisms

Securing LAN Communications with Blockchain Principles EL YOUSSOUFI SALMAN ESIN, International University of Rabat [email protected] Abstract—This work proposes a novel blockchain-inspired protocol to enhance the security of Local Area Network (LAN) communications against Man-in-the-Middle (MITM) attacks such as ARP spoofing. Conventional LAN protocols lack mechanisms to ensure packet integrity and authenticity, making them vulnerable to tampering and eavesdropping. In response, this protocol introduces a decentralized messaging framework where each encrypted packet is broadcast to all LAN nodes and includes a cryptographic hash of the previous message. This hash chaining approach mirrors blockchain’s immutable ledger model, enabling all nodes to validate message integrity collaboratively. Only the intended recipient can decrypt the content, preserving confidentiality. By distributing verification responsibilities across the LAN, the system eliminates the need for a central authority, thereby increasing resilience to insider threats. While inspired by blockchain’s structure, the proposed method avoids heavy consensus mechanisms, offering a lightweight yet tamper-evident communication model. Performance considerations and scalability limits are also addressed, including potential bandwidth, latency, and storage overheads. I. INTRODUCTION Man-in-the-Middle (MITM) attacks on local networks often exploit weak link-layer protocols (e.g. ARP spoofing) to intercept and modify traffic. For example, ARP poisoning is “a Man-in-the-Middle (MitM) attack that allows attackers to intercept communication between network devices” [1]. Conventional LAN communications (e.g. Ethernet or Wi-Fi) do not inherently prevent a malicious node from eavesdropping or tampering with packets. To counter this, a novel proposal adapts blockchain principles at the LAN level: every packet is broadcast to all nodes, encrypted for confidentiality, and chained by hashes for integrity. In this way, only the intended recipient can decrypt the data (protecting confidentiality), and each message includes a hash of the previous one (creating a tamper-evident log). If any packet were altered, the hash chain would break, immediately signaling interference. II. BLOCKCHAIN FUNDAMENTALS Blockchain is a distributed, tamper-evident ledger that links data in a chain by cryptographic hashes [2]. In such a ledger, no central authority is needed: each participant has a full copy of the chain and independently verifies new blocks. “Blockchains are tamper evident and tamper resistant digital ledgers implemented in a distributed fashion,” and once a transaction is published, it “can be changed [only] with difficulty” [2]. Each block contains a hash pointer to the previous block, so any alteration to past data invalidates all following hashes [3]. This hash-chain property is the core of blockchain’s integrity guarantee. Another key feature is decentralization: the system requires “a decentralized data management system for storing and sharing the data and transactions” across all nodes [3]. In essence, blockchain provides a community-wide, append-only log: everyone sees all entries, and no single node can secretly rewrite history without detection. III. BLOCKCHAIN PRINCIPLES FOR NETWORK SECURITY To apply blockchain ideas to network traffic, each communication packet must be treated as a blockchain transaction. Each LAN node takes part in message validation and recording rather than a central router or server authorizing or logging traffic. Single points of vulnerability are eliminated by this decentralization (no single node is ”trusted” more than others). In actuality, it is possible to see every node keeping a local log of every witnessed (encrypted) message together with the hash of the most recent message it deems legitimate. . By broadcasting packets to all peers, a node cannot quietly drop or alter a message without other nodes noticing a broken hash link. Prior work has noted these benefits: for instance, Yao et al. propose a blockchain-based WLAN authentication where “decentralization and tamper resistant characteristics of the blockchain” make the network information transparent and secure [4]. Similarly, blockchain-based schemes have been studied for detecting MITM in industrial IoT networks: Ahmad et al. show that a private blockchain can form a “zero-trust ecosystem” where tampering with in-transit data is quickly evident [5]. In both cases, blockchain’s cryptographic links ensure that any unauthorized message modification is detectable. IV. PROPOSED BLOCKCHAIN-BASED LAN PROTOCOL The envisioned protocol works as follows. When a node (Alice) wants to send a packet to another (Bob), it encrypts the payload with a key known only to Bob (e.g. using Bob’s public key or a shared secret). It then broadcasts this ciphertext to all LAN nodes. Since only Bob can decrypt it, confidentiality is preserved. Simultaneously, Alice includes in the packet a cryptographic hash of the previous message in the conversation (this could be a hash of the last packet’s contents or of the last blockchain entry). Upon receiving the broadcast, every node records the new hash and checks that it correctly chains to the last hash they saw. Bob decrypts and uses the data if needed. Because everyone sees the same hashed pointer, Feature Technique/Algorithm Purpose Encryption RSA with OAEP padding Confidentiality Digital Signature RSA signature (PKCS#1 v1.5) + SHA-256 hash Authenticity & integrity Packet Hashing SHA-256 Integrity & blockchain chaining Blockchain Linked hash chain of packets Tamper-evident immutable log Sequence Number Incrementing integer Order & replay protection any attempt by an attacker to inject or alter a message would break the chain consistency and be immediately apparent. This is akin to building a blockchain of network packets: each new “block” (packet) includes the hash of its predecessor, creating a continuous, immutable log. As NIST observes, this ensures that “no transaction can be changed once published” under normal operations [2]. In effect, the entire LAN acts as a distributed consensus system for message integrity, even without heavy consensus algorithms: the shared log and hash pointers suffice to verify authenticity and order. Key security properties follow naturally. Confidentiality is enforced by encryption: even though packets are broadcast, only the intended recipient (and any authorized auditors) can decrypt them. This is similar in spirit to broadcast encryption schemes, where a message is sent to many but only target users can open it. Integrity and tamper-evidence come from the hash chaining: any changed byte in packet k would alter its hash, so when node Alice sends packet k+1 including H(pkt k), everyone sees a mismatch. As the TechScience review explains, “the chain between blocks makes any alteration or change to any block affect all subsequent blocks,” so “records cannot be altered retroactively without the alteration of all subsequent blocks” [3]. In our LAN context, that means an attacker cannot slip in or change a packet without immediately invalidating all following hashes—something that all honest nodes would notice. Because every node maintains the history, trust is fully decentralized. There is no single router or server that must be trusted to forward packets faithfully. Instead, nodes cooperatively maintain a shared ledger of communication. As Singh et al. discuss for IoT, blockchain requires “a community of users to record transactions in a shared ledger” without a central authority. Analogously, our LAN protocol has each node act like a blockchain peer: everyone stores and verifies the log of messages. In Yao et al.’s WLAN blockchain system, for example, “everyone [knows] exactly information about the WLAN” through the shared ledger, enhancing transparency and security [4]. This means that if any device were compromised or a rogue device attempted a MITM attack, it could not hide its actions—any unexpected hash or missing log entry would reveal the tampering. V. PRIOR WORK AND RELATED SCHEMES Blockchain research for network security is expanding. In order to replace centralized Access Point trust and make credential leaks significantly more difficult, Yao and Xie (2019) created a blockchain-based authentication mechanism for WLANs. Similar concepts have been put up by others in IoT and smart grid situations. In order to detect illegal data alterations, Ahmad et al. (2021 IEEE DMC) create a Alice (Sender) Bob (Receiver) LAN Segment Eve (MITM) Encrypted Packet + Hash Intercept Attempt H1 H2 H3 Hash Chain Fig. 1. Blockchain-Based LAN Protocol: Packet encryption, hash chaining, and MITM detection private blockchain for solar systems. They demonstrate that when an MITM modifies an inverter instruction, the ledger ”clearly shows” tampering. Similarly, in their evaluation of blockchain’s function in IoT security, Saurabh et al. stress that the technology is specifically suited to distributed networks and ”requires a decentralized data management system” for integrity. According to a different study, adding blockchain protections to an authentication payload (e.g., by using its block hash and consensus) significantly improved resistance to MITM. The payload became ”well encrypted and safe enough,” improving security test results against MITM by 95%. These pieces support the main thesis, which is that blockchain techniques can identify or stop MITM-style manipulation by chaining and replicating communication records. VI. PERFORMANCE AND SCALABILITY CONSIDERATIONS Blockchain implementation at the LAN layer is expensive, despite its potential for security. Every transaction in traditional blockchain networks is broadcast from peer to peer, which can take a lot of bandwidth. To ensure that ”messages percolate across the network over many paths,” for instance, blockchain nodes usually replay each message to all of their peers. According to GhostVolt, ”the ’broadcast’ communication style of the blockchain means that it requires a large amount of bandwidth.” This broadcast-heavy architecture uses a lot of bandwidth. Performance may be strained by this overhead in a crowded LAN with numerous packets. Furthermore, compared to local networks, which often process hundreds of transactions per second, public blockchains like Ethereum only process 10 to 15 transactions per second. While our LAN protocol might not use full blockchain consensus (no mining is proposed), each node still must compute hashes and process every message, which adds latency and computational load. Additionally, there are storage and state issues: every node needs to have the most recent hash log (or whole ledger), and it might be difficult to securely manage key distribution such that only the designated recipient can decode. Without additional optimization, the technique might not scale well to very high-throughput or huge LANs in practice due to these overheads. Throughput constraints are being actively addressed by researchers working on ”Blockchain3.0” systems, and methods such as off-chain channels (Lightning networks) have been proposed to lessen on-chain stress. Performance bottlenecks could be avoided by adapting similar concepts to LAN blockchains (e.g., local sub-channels for frequent short messages). VII. CONCLUSION Using blockchain principles at the LAN layer offers a novel defense against MITM attacks by broadcasting encrypted messages and linking them via hashes. This creates a decentralized, tamper-evident log of all communication: every node in the LAN holds a copy and verifies the integrity chain, making it almost impossible for an attacker to alter packets undetected. Prior studies have shown that such tamper-proof logging and decentralization markedly increase resistance to MITM threats. However, the approach also introduces nontrivial overhead in bandwidth, computation, and storage, which must be weighed against its security gains. Overall, the literature indicates that while promising, blockchain-based LAN protocols will require careful engineering (e.g. efficient hashing, selective broadcasting, or off-chain techniques) to be practical. As a research direction, it merges distributed ledger technology with network protocol design, and has parallels in recent blockchain-security systems. REFERENCES [1] Imperva, ”What is ARP Spoofing”, [Online]. Available: https://www. imperva.com/learn/application-security/arp-spoofing/ [2] NIST, ”Blockchain Technology Overview,” NIST IR 8202, 2018. [3] TechScience, ”Using Blockchain Technology in Mobile Network,” 2022. [4] Yao and Xie, ”A Blockchain-Based Authentication Mechanism in WLAN,” CNCI, 2019. [5] S. Ahmad et al., ”Blockchain-Based MITM Detection for Photovoltaic Systems,” IEEE DMC, 2021.