ToyPublicKeys.jl is toy implementation of selected public key-based cryptosystems. It tries to be proper, however it does not provide any formal garantues on correctness or robustness. It is mostly a preview of how a Julia native (besides GMP bindings) implementation of asymetric cryptosystems could look like :)
Try it out as https://juliahub.com/ui/Packages/General/ToyPublicKeys
import Pkg; Pkg.add("ToyPublicKeys")