1. An embedded device, comprising: a memory; and a microprocessor configured to execute executable instructions stored in less than a thousand bytes of the memory to: generate a subset-sum problem and a Goldreich-Levin hash function, wherein: generating the subset-sum problem includes generating an N by N bit matrix M, wherein x and y are N bit vectors and y=M·x; and generating the Goldreich-Levin hash function includes generating an N by K bit matrix H, wherein z=H·x; encrypt a communication from the embedded device using z; receive an updated vector x; generate an updated matrix M based on the updated vector x; generate an updated matrix H based on the updated vector x; and encrypt an additional communication from the embedded device using an updated z, wherein the updated z is based on the updated matrix H and the updated vector x.