<![CDATA[The controller area network (CAN) communication protocol used in vehicles relies on fixed message identifiers, which makes it vulnerable against frame injection and replay attacks. This study proposes an efficient lightweight hardware method that randomizes the identifier while preserving the priority rules that control bus arbitration. The design is implemented in a hardware description language (Verilog) and uses a linear feedback shift register (LFSR) as the randomization engine. The upper four bits of the identifier are kept unchanged to retain priority, where the lower seven bits are randomized. The module supports reseeding from a cryptographically secure random source. However, for the baseline statistical evaluation, reseeding was intentionally disabled to measure the intrinsic distribution. The design was evaluated using Xilinx Vivado environment. Statistical analysis was performed on 8,188 randomized ID, achieving a Shannon entropy of 6.999978 bits (maximum 7), and a chi‑square goodness‑of‑fit test that showed no detectable deviation from a uniform distribution ( = 0.2482, -value ≈ 1). Synthesis to a Artix-7 field‑programmable device reported only 15 lookup tables and 23 flip-flops (<0.1% of resources), with a maximum operating frequency of 482 MHz, indicating a minimal hardware footprint. The mechanism was further validated on a physical CAN testbed confirming protection against replay and spoofing attempts, while the mechanism added no measurable bus or timing overhead. These results show that simple, hardware‑level identifier randomization can strengthen in‑vehicle communication while keeping arbitration behaviour intact and without requiring protocol changes.]]>
