Adaptive Analysis with HD Model on XOR Operation in Cipher Chips

Power consumption is considered as a kind of cipher chip´s side channel leakage, which is correlation to the internal values in the chips. However, analysis with the side channel leakage built from Hamming-Weight (HW) model of secret key could only retrieve the equivalent Hamming-Weight classes of the key. To solve the problem, a new side channel analysis model is built from the Hamming-Distance (HD) of two operands of XOR operations in cryptographic algorithms and a new adaptive chosen plaintext analysis method is proposed. This method adaptively changes one bit of the chosen plaintext to approach the secret key one bit a step, and retrieves the whole secret key finally. Attack experiment on AES encryption executed in an AT89C52 microcontroller verified that the proposed method is feasible.