A side-channel analysis resistant reconfigurable cryptographic coprocessor is designed and fabricated in 0.18μm CMOS with 1.8V supply and 100MHz frequency, supporting multiple block cipher algorithms of AES, DES, RC6 and IDEA. Our countermeasure utilizes idle processing elements existed in reconfigurable array to do dummy operations to hide leakage information. This method has little impact on area and frequency, and it is flexible after silicon. It resists SPA and DPA without distinguishing the encryption region. And by correlation-based electromagnetic analysis, measurement to disclosure of DES enhances 36 times with partial countermeasures and AES discloses no subkey after more than one million electromagnetic traces with full countermeasures.