Security in the Shell (SSh) describes a highly interdisciplinary and ambitious research project that poses, to both scientific fields that it connects, intellectual and scientific challenges that are as fascinating as they are unprecedented. The name and acronym play with one of the most important concepts in modern security technology, while at the same time embracing the physical object that is at the heart of the project: a shell of Cholesteric Liquid Crystal (CLC). This shell is not a virtual computing construct but a real physical object, constituting, first, a fascinating playground for fundamental soft matter physics experiments. It differs from standard sample geometries through the lack of edges and the tight confinement with curved boundaries between two immiscible liquids, impacting the liquid crystal self-assembly in profound ways. At the same time, an array of such shells holds great potential for providing a potentially game-changing security tool, of value for authenticating persons, objects of high value like artworks, and even drugs and foods, the authenticity of which can be a matter of life and death. The truly innovative cut of SSh is that this new authentication solution, based on the unique dynamic optical patterns that the shell array generates (in security terminology, it is an optical Physical Unclonable Function, or PUF), can be applied to objects of almost any kind and sizes.To harness this rich potential, we propose a transdisciplinary, yet highly focused, research thrust, to better understand the behavior of CLCs under the unorthodox conditions that the shell topology provides, to move to food-grade cellulose-based materials to allow incorporation in objects that will be ingested, and to analyze from a computer science point of view their features as a security element, their strengths and weaknesses in this role, and to propose protocols for ensuring a secure and reliable authentication process. In this way SSh aims not just to carry out stimulating materials and computer science research, but by combining these two domains it can give a major contribution to the fight of the plague of counterfeit goods.
Figure 2: Cholesteric liquid crystal shells made from polymerizable mesogenic materials, just after production, viewed using transmission polarizing microscopy. Scale bar: 500 μm.
