# Physical cryptographic primitives by chemical vapor deposition of layered MoS2

## TL;DR

This paper presents a novel physical cryptographic primitive based on layered MoS2 films synthesized via chemical vapor deposition, leveraging their random layer distribution and optical properties to generate secure cryptographic keys.

## Contribution

The study introduces a new class of cryptographic primitives using MoS2 monolayer films with engineered speckle density, demonstrating their potential for security applications.

## Key findings

- The MoS2 film exhibits complete spatial randomness of multilayer islands.
- Optical responses depend on the random layer distribution, enabling key generation.
- Security tests confirm the keys' uniqueness, reliability, and uniformity.

## Abstract

Development of physical cryptographic primitives for generating strong security keys is central to combating security threats such as counterfeiting and unauthorized access to electronic devices. We introduce a new class of physical cryptographic primitives from layered molybdenum disulfide (MoS2) which leverages the unique properties of this material system. Using chemical vapor deposition, we synthesize a MoS2 monolayer film covered with speckles of multilayer islands, where the growth process is engineered for an optimal speckle density. The physical cryptographic primitive is an array of 2048 pixels fabricated from this film. Using the Clark-Evans test, we confirm that the distribution of islands on the film exhibits complete spatial randomness, making this cryptographic primitive ideal for security applications. A unique optical response is generated by applying an optical stimulus to the structure. The basis for this unique response is the dependence of the photoemission on the number of MoS2 layers which by design is random throughout the film. The optical response is used to generate cryptographic keys. Standard security tests confirm the uniqueness, reliability, and uniformity of these keys. This study reveals a new opportunity for generating strong and versatile nano-engineered security primitives from layered transition metal dichalcogenides.