A Secure Audio Interface to Prevent Spying of Audio Data on Voice Controlled Devices

The advent of voice based digital assistants has made life simpler for the current generation. Devices such as Amazon Echo and google home assists humans to perform user instructed actions from the comfort of their couch. Utilizing interfaces such as speakers and microphones, the voice based assistants accept and process the voice commands using Host Application Processor (AP). However, these devices turned out to be a victim of cyber-crime attacks, when connected to the network. By rooting into the AP, the attacker can manipulate the speaker or microphone and gain the samples of user's audio data. In this research, a secure subsystem for voice based devices has been developed to prevent eavesdropping of audio samples. The secure subsystem contains an I2S and AES controller, where the audio data captured by I2S is encrypted using AES engine. The encrypted audio data is loaded into the application space, ensuring the confidentiality. The playback of audio data is performed in reverse fashion. The results of the developed subsystem corroborate the integrity and security of audio data during encryption and decryption.