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
