A data processing system includes an application processor, a memory device, and a channel connecting the application processor and the memory device. The application processor encrypts first data using a first encryption key and a first initialization vector in response to a write command, and transmits first encrypted data to the memory device through the channel. The memory device decrypts the first encrypted data using a second encryption key and a second initialization vector, and stores first decrypted data in a memory core. The second encryption key and the second initialization vector are stored in the memory device. The first encryption key is the same as the second encryption key, and the first initialization vector is the same as the second initialization vector.