Abstract: The article analyzed the CMOS logical gate's electric current characteristic under the active status, explained data and electromagnetic emissions correlation of ICs, established the electromagnetic information leakage hamming dislance model in registers level. Aimed at the data encryption standard (DES) cryptographic system realized by the P89C668 microcomputer, correlation electromagnetic analysis (CEMA) algorithm was described, the choice of attack point D and the computational method were analyzed, an attack experiment was processed by CEMA, thereby which made us obtain 48-bit sulrkey of the 16th round of DES. The result shows that EM information leakage exists in CMOS integrated circuit during work, XOR operation in each round of DES is an attack point. The correlation analysis is more effective than the differential attack. It can provide a basis for implementing protective measures in the cryptographic systems.

Key words: CEMA, EM information leakage, Data correlation, DES, SCAs