An Optical Pointing Telescope for Radio Astronomy

Design details are given for a stable optical pointing telescope for radio astronomy. The telescope is a 100 mm f/15 refractor with the objective glued to a ring of three blade flexures, an insulated and vented Invar tube mounted on flexures, and an axially symmetric camera mount. For a pair of identical telescopes, the rms differential pointing stability is 0.1" hr^(-1) over 2 hr, 0.05" day^(-1) over 3 days, 0.03" K^(-1), and 0.1″ after a 90° change in elevation

Physical key-protected one-time pad

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

Reconfigurable random bit storage using polymer-dispersed liquid crystal

We present an optical method of storing random cryptographic keys, at high densities, within an electronically reconfigurable volume of polymer-dispersed liquid crystal (PDLC) film. We demonstrate how temporary application of a voltage above PDLC's saturation threshold can completely randomize (i.e., decorrelate) its optical scattering potential in less than a second. A unique optical setup is built around this resettable PDLC film to non-electronically save many random cryptographic bits, with minimal error, over a period of one day. These random bits, stored at an unprecedented density (10 Gb/mm^3), can then be erased and transformed into a new random key space in less than one second. Cryptographic applications of such a volumetric memory device include use as a crypto-currency wallet and as a source of resettable “fingerprints" for time-sensitive authentication

Physically secure and fully reconfigurable data storage using optical scattering

This paper presents an optical method of storing random cryptographic keys within a reconfigurable volume of polymer-dispersed liquid crystal (PDLC). We suggest a PDLC-based device that functions as an integrated optical physical unclonable function (PUF). Our device can selectively access a dense set (up to 10 Gb/mm^3 in theory) of non-electronically saved random bits. Furthermore, this optical PUF can fully erase and transform these bits into a new random configuration in less than one second, via a simple electrical signal. When a short voltage spike is applied across the PDLC film interface, its optical scattering potential completely decorrelates. We confirm this phenomenon with detailed experiments on a proof-of-concept device, thereby suggesting the security use of a new class of optical materials as (i) securely and efficiently reconfigurable PUFs, and (ii) an erasable storage medium for random cryptographic keys. Our work can eventually help address the challenge of quickly and completely erasing sensitive digital electronic memory and/or key material. It also establishes a new and hopefully fruitful connection between security questions and the material sciences

Physical key-protected one-time pad

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 mm3 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