The security of CPU smart cards, which are widely used throughout China, is currently being threatened by side-channel analysis. Typical countermeasures to side-channel analysis involve adding noise and filtering the power consumption signal. In this paper, we integrate appropriate preprocessing methods with an improved attack strategy to generate a key recovery solution to the shortcomings of these countermeasures. Our proposed attack strategy improves the attack result by combining information leaked from two adjacent clock cycles. Using our laboratory-based power analysis system, we verified the proposed key recovery solution by performing a successful correlation power analysis on a Triple Data Encryption Standard (3DES) hardware module in a real-life 32-bit CPU smart card. All 112 key bits of the 3DES were recovered with about 80 000 power traces.