This paper provides a developed cryptosystem for data encryption based on using the Discrete Fourier Transform (DFT). The encryption side using the DFT method for performing the main security development that is considered as the main encryption process in the developed cryptosystem. The primary ciphered plaintext data must be prepared as a block of (N) data, and entered to the DFT part. The decryption side uses as an inverse DFT method, to get back the primary ciphered plaintext from the received cipher text. The proposed method applied to classical encryption method, and can be applied to a stream cipher method. The validity of the developed encryption process is illustrated through many numerical examples.