A combined countermeasure against DPA and implementation on DES

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 effective countermeasures against DPA attack. This paper propose a novel countermeasure which associating masking with RDI, further, Multi-Masking instead of Transformed Masking is proposed in order to defend DPA attack based on hamming distance model. The combined countermeasure is implemented on Data Encryption Standard (DES). The results show that combined countermeasure defends DPA attack with 10⁵ power traces, and increases 40% ability against DPA.