approximate-gcd/src/matrix.rs
2025-04-03 09:42:25 +02:00

120 lines
3.0 KiB
Rust

use rug::ops::Pow;
use std::ops::{Index, IndexMut};
type Element = rug::Integer;
macro_rules! int {
($x:expr) => {
rug::Integer::from($x)
};
}
#[derive(Debug, PartialEq)]
pub struct Matrix {
pub n: usize, //rows
pub m: usize, // columns
values: Vec<Element>,
}
impl Matrix {
pub fn new(n: usize, m: usize, values: Vec<Element>) -> Option<Self> {
if n*m == values.len() {
Some(Matrix { n, m, values })
} else {
None
}
}
pub fn new_lattice(noise_bits: usize, ciphertexts: Vec<Element>) -> Option<Self> {
let n = ciphertexts.len();
let mut values = Vec::with_capacity(n * n);
// First row: [2^noise_bits, ciphertexts[1], ..., ciphertexts[t]]
values.push(int!(2u64).pow(noise_bits as u32));
values.extend_from_slice(&ciphertexts[1..]);
// -x0 on diagonal, 0 everywhere else
let x0 = &ciphertexts[0];
for i in 1..n {
let mut row = vec![int!(0); n];
row[i] = -x0.clone();
values.extend(row);
}
Matrix::new(n, n, values)
}
}
impl Index<(usize, usize)> for Matrix {
type Output = Element;
fn index(&self, index: (usize, usize)) -> &Self::Output {
if index.0>=self.m || index.1 >= self.n {
panic!();
}
&self.values[(self.n * index.0) + index.1]
}
}
impl IndexMut<(usize, usize)> for Matrix {
fn index_mut(&mut self, index: (usize, usize)) -> &mut Self::Output {
if index.0>=self.m || index.1 >= self.n {
panic!();
}
&mut self.values[(self.n * index.0) + index.1]
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn simple_matrix() {
assert_eq!(
Matrix {
n: 2,
m: 2,
values: vec![int!(1), int!(2), int!(3), int!(4)],
},
Matrix::new(2, 2, vec![int!(1), int!(2), int!(3), int!(4)]).unwrap()
);
assert!(Matrix::new(2, 2, vec![int!(1), int!(2)]).is_none());
}
#[test]
fn indexes() {
let mut m = Matrix::new(2, 2, vec![int!(1), int!(2), int!(3), int!(4)]).unwrap();
assert_eq!(m[(0, 0)], int!(1));
assert_eq!(m[(1, 0)], int!(3));
m[(1, 0)] = int!(5);
assert_eq!(m[(1, 0)], int!(5));
let m2 = Matrix::new(3, 2, vec![int!(1), int!(2), int!(3), int!(4), int!(5), int!(6)]).unwrap();
assert_eq!(m2[(0, 2)], int!(3));
assert_eq!(m2[(1, 0)], int!(4));
}
#[test]
fn test_new_lattice() {
let ciphertexts = vec![int!(5), int!(8), int!(12)];
let noise_bits = 2;
let expected_values = vec![
int!(4),
int!(8),
int!(12),
int!(0),
int!(-5),
int!(0),
int!(0),
int!(0),
int!(-5),
];
let lattice = Matrix::new_lattice(noise_bits, ciphertexts).unwrap();
assert_eq!(lattice.n, 3);
assert_eq!(lattice.values, expected_values);
}
}