Secure voice communication via GSM network

In this study, a system is developed which communicates through GSM mobile phones and provides protection for interviews against third parties including with service providers developed. GSM line is sensitive to human speech to be more efficient and provide more quality for transmission. In addition, a tool should be used to compress speech to transmit speech over GSM. For these reasons, speech cannot be transmitted to the GSM line directly after encrypted. In this study, the encrypted speech which is a digital data stream, formed speech like waveform by the designed coder to transmit through the GSM line. FPGA implementation of AES is used for encryption of digital data stream. Desired speech characteristics are obtained by scanning the database of NTIMIT, and then LBG algorithm is used to design codebooks which include speech parameters. A coder is designed to synthesize speech like waveforms from the encrypted digital data stream.