title: Physical key-protected one-time pad.
abstract: We describe an encrypted communication principle that forms a secure link between two parties without electronically saving either of their keys. Instead, random cryptographic bits are kept safe within the unique mesoscopic randomness of two volumetric scattering materials. We demonstrate how a shared set of patterned optical probes can generate 10 gigabits of statistically verified randomness between a pair of unique 2 mm(3) scattering objects. This shared randomness is used to facilitate information-theoretically secure communication following a modified one-time pad protocol. Benefits of volumetric physical storage over electronic memory include the inability to probe, duplicate or selectively reset any bits without fundamentally altering the entire key space. Our ability to securely couple the randomness contained within two unique physical objects can extend to strengthen hardware required by a variety of cryptographic protocols, which is currently a critically weak link in the security pipeline of our increasingly mobile communication culture.
authors.affiliation: Departments of Electrical Engineering and Bioengineering, California Institute of Technology, Pasadena, CA 91125.
authors.forename: Roarke
authors.initials: R
authors.lastname: Horstmeyer
authors.affiliation: Departments of Electrical Engineering and Bioengineering, California Institute of Technology, Pasadena, CA 91125.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Judkewitz
authors.affiliation: Biomedical Photonic Imaging Group, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, P.O. Box 217, 7500 AE Enschede, the Netherlands.
authors.forename: Ivo M
authors.initials: IM
authors.lastname: Vellekoop
authors.affiliation: Departments of Electrical Engineering and Bioengineering, California Institute of Technology, Pasadena, CA 91125.
authors.forename: Sid
authors.initials: S
authors.lastname: Assawaworrarit
authors.affiliation: Departments of Electrical Engineering and Bioengineering, California Institute of Technology, Pasadena, CA 91125.
authors.forename: Changhuei
authors.initials: C
authors.lastname: Yang