A novel power attack resistant cryptosystem is presented. Security in digital computing and communication is becoming increasingly important. Design techniques that can protect cryptosystems from leaking information have been studied by several groups. Power attacks, which infer program behavior from observing power supply current into a processor core, are important forms of attack. Various methods have been proposed to counter the popular and efficient power attacks. However, these methods do not adequately protect against power attacks and may introduce new vulnerabilities. We address a novel approach against power attacks, i.e., dynamic voltage and frequency switching (DVFS). Three designs, naive, improved and advanced implementations, have been studied to test the efficiency of DVFS against power attacks. A final advanced realization of our novel cryptosystem is presented; it achieves enough high power trace entropy and time trace entropy to block all kinds of power attacks, with 27% energy reduction and 16% time overhead for DES encryption and decryption algorithms.