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FPGA-based 128-bit Chaotic Encryption Method for Voice Communication

In communication exchange, the requirement for secure channel is high, notably to prevent unintended parties to take the private or classified messages. We developed a prototype of secure voice channel using 128-bit Chaotic cryptographic algorithm employing Cipher Feedback as an alternative for small but reliable algorithm. Two Spartan-3 FPGA boards were employed to implement the prototype of the encryption and decryption modules on both ends of a simplex voice channel. The channel was tested in four scenarios: unsecure channel, fully secure channel, eavesdropping and decrypted unsecure messages. The testing result shows that the Mean Square Error (MSE) and Total Harmonic Distortion with Noise (THD-N) in fully secure channel is very low compared to eavesdropping scenario. Moreover, the test also reveals that the quality of recovered encrypted message is very similar with message in unsecure channel. Therefore, these confirms that the cryptographic algorithm works well in securing the channel for asynchronous communication.