Audio encryption using polarized light beam

In recent years, the security of audio data has become paramount in terms of personal information, national security, and forensic evidence. However, most reported systems use digital algorithms and lack their implementation in the optical domain, which can provide better security due to the use of physical keys and high speed. In addition, recently developed phase-encoded audio encryption schemes in the optical domain have quality limitations due to precise wavefront measurement and control. Perfect experimental alignment to achieve good quality retrieved data is very challenging, due to which no optical implementation of voice security has been reported. This work introduces a robust audio encryption scheme using the polarization property of a light beam. Initially, one-dimensional (1D) audio combined with a random dataset acts as an encryption key and converts it to 1D cipher audio, which is transformed into a two-dimensional (2D) cipher-audio map. Subsequently, this is fragmented into several 2D segments, which are then encoded into the light beam using binary polarization states. An arbitrary sequence is maintained during encoding of the 2D segments into binary polarization states. The demonstrated technique is a non-interferometric method, and the decryption can be achieved through intensity recording only.