Physical Encryption of Sensitive Gamma-Ray Templates

A warhead template that is derived from a gamma-ray spectrum would be considered sensitive information if used in an arms-control application. Any system that captures spectral information, even if an information barrier is used, will have an associated risk of information loss. This work assesses the possibility of “physically encrypting” a template such that the gamma-ray spectrum measured by a system is no longer considered sensitive but can still be used to confirm the presence of a treaty accountable item (TAI). To ensure that the template does not contain sensitive information, a mixture of radioisotopes and intervening material could be measured with a TAI, which would obscure the true gamma-ray spectrum of the TAI. The radioisotopes in the encrypting source and intervening material would be chosen by the host such that a combined measurement with the TAI would not be considered sensitive information. This paper explores this concept and outlines potential procedures that could be used for its implementation.