Without the luxury of full undergraduate training in mathematics, if one worked part time could the community list the smallest set of mathematical fields needed to understand homomorphic encryption? I know that linear algebra & lattice algebra is a must, but other than that I'd like to ask for guidance.
Specifically I'd like to use the schemes described in http://dl.acm.org/citation.cfm?id=2090262 "we offer a choice of FHE schemes based on the learning with error (LWE) or ring-LWE (RLWE) problems that have 2λ security against known attacks" - the paper also mentions arithmetic circuits, and gate computation.