Secure cryptographic communication using ultrasound audio for frictionless payment transactions and secure conversations over a short-range human audible/inaudible spectrum

Background: The aim of the study was to address these challenges by leveraging ultrasound audio as a means for secure cryptographic communication. By utilizing the human audible and inaudible audio spectrum, this approach eliminates the reliance on specialized hardware or traditional network technologies, such as bluetooth, wi-fi, NFC, or RF-based alternatives. Methods: Various mobile phones, tablets, and POS hardware devices with basic microphones and speakers were employed to test the communication channel's performance. The sensitivity of the devices in different environments, such as retail stores or crowded venues like stadiums, was taken into account.   Results: The results demonstrated the viability of the proposed secure cryptographic communication using ultrasound audio. Transactions, including payment processing, were successfully conducted without the need for specialized hardware or network connectivity. Conclusions: The proposed solution offers a reliable and cost-effective method for proximity detection, verification, and frictionless transactions. By leveraging the human audible and inaudible audio spectrum, this technology eliminates the need for specialized hardware or traditional network connectivity.