Towards Semantic-Preserving Obfuscation for Analysis-Resistant EVM Bytecode

Abstract

With the transparency of the Ethereum platform, deployed smart contracts remain permanently public, exposing their virtual machine code to risks such as reverse engineering, control-flow analysis and malicious behavior identification. Although several obfuscation approaches for the EVM have been proposed, existing solutions often suffer from limited resistance against advanced analysis techniques, insufficient structural transformation capability or excessive execution overhead. In this work, we propose a novel obfuscation framework for EVM bytecode that enhances security by combining semantic-aware transformations with control-flow perturbation techniques. The proposed framework significantly increases structural complexity, hinders Control Flow Graph (CFG) recovery and alters discriminative virtual machine code characteristics while preserving the semantic correctness of smart contracts. Experimental results demonstrate that the proposed framework achieves a 100% obfuscation success rate with an average cyclomatic complexity of 90.80. Across all 15 evaluated transformation combinations, the framework introduces an overall mean virtual machine code size increase of 15.99% and a mean gas overhead of 7.04%. Notably, the complete multi-layer pipeline (T1+T2+T3+T4) exhibits overheads of 29.73% for virtual machine code size and 12.58% for gas, which remain acceptable considering the achieved robust resistance against reverse engineering and automated static analysis.