AHardware implementation of DES with combined countermeasure against DPA

Differential Power Analysis (DPA) reveals the secret key from the cryptographic device by side channel power leakage. Masking and Random Delay Insertion (RDI) are two countermeasures against DPA attack. But masking or RDI alone does not prevent DPA attack, they only enhance the difficulty of the attack. This paper proposes a novel countermeasure which associating masking with RDI. Furthermore, multi-masking instead of transformed masking is proposed in order to defend DPA attack based on hamming distance model. The combined countermeasure is implemented and verified on Data Encryption Standard (DES) algorithm. The results show that the combined countermeasure defends DPA attack with 10⁵ power traces, and increases 40% ability against DPA with only 28% performance penalty.