Exploiting the acousto-optic effect for developing secure digital identifiers

Cybersecurity is rooted in hardware to achieve high security. Physical unclonable functions (PUFs) are cryptographic primitives that implement one-way functions to generate cryptographic keys on-demand. Current approaches implement PUFs using microelectronic circuits that exploit the random manufacturing variabilities. Other alternatives exploit optical principles to offer higher security. However, their reliability is compromised by environmental effects and integrated systems are still to be realized. Here a novel approach is proposed to enhance reliability and potentially enable integration in digital security systems. The proposed method uses the acousto-optical effect to interrogate optical PUFs, avoiding precision alignment of moving parts and bulky equipment. This way of interrogating the PUF can also be miniaturized in a photonic integrated circuit. The experimental results demonstrate the feasibility of this approach and the potential for generating a large number of truly random cryptographic keys.