Stream cipher is one of the most important branches of cryptography that can be implemented by using software and hardware components. In this thesis, the stream cipher (presented by Geff generator) based on the linear feedback shift register technology was implemented by using program written in Borland C++ programming language. Then the data in form of sound wave was recorded by using a microphone on the computer and encrypted file was send to another computers (and the encrypted file) was decrypted. This operation was applied by using a file in image form and (also by using file) was written in (Word 2000) under name (data) and the result of this file (encrypted and decrypted file) was illustrated in the thesis also the hardware circuit was implemented and output bit was recorded for several times, first the data was entered manually, then an analog signal with maximum frequency of 10 kHz was converted to digital form by using the integrated circuit (ADC 574, ADQ585) and the shift register 74174 with frequency of 2MHz that was supported by using 8085 microprocessor. The encrypted data was transmitted using the optical transmitter (HFBR-1402) through optical cable. A multimode optical fiber with attenuation of 0.2 dB/km and received by using optical receiver (HFBR 2402). The power budget and maximum distance and bit rate for the optical design was calculated by using the experimental results and the optical fiber communication circuit proved its efficiency. The comparison between the software and hardware Geff generator was illustrated in the conclusion.