<p>This paper presents an attack detection approach using data encryption for the cyber-physical systems with the purpose of (i) detecting the false data injection (FDI) attacks, and (ii) significantly improving the attack detection rate without sacrificing any system performance. To this end, a dynamic encryption scheme (DES) is designed to realize the encrypted transmission of measurement output, in which the secret key is updated dynamically using historical measurement outputs. Then, the effectiveness of DES in detecting FDI attacks is discussed through the theoretical analysis. It is certified that, the attack detection approach proposed in this paper can increase the anomaly detector’s attack detection rate by accumulating the effects of FDI attacks on the estimation residual. When there are no attacks, the DES can restore the original measurement output. In this case, such a scheme would not deteriorate the system performance. Moreover, the proposed attack detection approach can also be used to detect replay attacks. Finally, the effectiveness of the proposed attack detection approach is demonstrated on an IEEE 6 bus power system.</p>