Abstract: Publio-key cryptography, such as RSA and DSA, adopt sliding window method for modular exponentiation, from which sidcchannel information can be leaked while accessing Cache during execution, thus private key can be de- crypted. Exponent analysis algorithm is the key point to improve the efficiency of the attack. I3y analyzing the shortco- ming of previous work,this paper farther analyzed the relationship between Cacho-access trace and precomputed multi- pliers and proposed an improved exponent analysis algorithm based on window-value identifying. Experiments were made to prove the efficiency the improved algorithm and results showed that the improved algorithm was able to recover 60 0 o exponential bits, which is better than the previous result 47 0 o. In the end, the application of the improved algo- rithm was showed on RSA and DSA.

Key words: Sliding window algorithm, Modular exponentiation, RSA, DSA, Cache timing attack