generalized-fhe: add GLWE encryption & decryption

arith/src/ringq.rs

@@ -13,6 +13,9 @@ use anyhow::{anyhow, Result};
 
 use crate::Ring;
 
+// NOTE: currently using fixed-size arrays, but pending to see if with
+// real-world parameters the stack can keep up; if not will move everything to
+// use Vec.
 /// PolynomialRing element, where the PolynomialRing is R = Z_q[X]/(X^n +1)
 /// The implementation assumes that q is prime.
 #[derive(Clone, Copy)]

arith/src/tuple_ring.rs

@@ -10,9 +10,6 @@ use std::{array, ops};
 
 use crate::Ring;
 
-// #[derive(Clone, Copy, Debug)]
-// pub struct TR<R: Ring, const K: usize>([R; K]);
-
 /// Tuple of K Ring (Rq) elements. We use Vec<R> to allocate it in the heap,
 /// since if using a fixed-size array it would overflow the stack.
 #[derive(Clone, Debug)]