use crate::{cbd::*, ntt::*, params::*, reduce::*, symmetric::*};
#[derive(Clone)]
pub struct Poly {
pub coeffs: [i16; KYBER_N],
}
impl Copy for Poly {}
impl Default for Poly {
fn default() -> Self {
Poly {
coeffs: [0i16; KYBER_N],
}
}
}
impl Poly {
pub fn new() -> Self {
Self::default()
}
}
pub fn poly_compress(r: &mut [u8], a: Poly) {
let mut t = [0u8; 8];
let mut k = 0usize;
let mut u: i16;
match KYBER_POLYCOMPRESSEDBYTES {
128 => {
for i in 0..KYBER_N / 8 {
for j in 0..8 {
u = a.coeffs[8 * i + j];
u += (u >> 15) & KYBER_Q as i16;
t[j] = (((((u as u16) << 4) + KYBER_Q as u16 / 2) / KYBER_Q as u16) & 15) as u8;
}
r[k] = t[0] | (t[1] << 4);
r[k + 1] = t[2] | (t[3] << 4);
r[k + 2] = t[4] | (t[5] << 4);
r[k + 3] = t[6] | (t[7] << 4);
k += 4;
}
}
160 => {
for i in 0..(KYBER_N / 8) {
for j in 0..8 {
u = a.coeffs[8 * i + j];
u += (u >> 15) & KYBER_Q as i16;
t[j] = (((((u as u32) << 5) + KYBER_Q as u32 / 2) / KYBER_Q as u32) & 31) as u8;
}
r[k] = t[0] | (t[1] << 5);
r[k + 1] = (t[1] >> 3) | (t[2] << 2) | (t[3] << 7);
r[k + 2] = (t[3] >> 1) | (t[4] << 4);
r[k + 3] = (t[4] >> 4) | (t[5] << 1) | (t[6] << 6);
r[k + 4] = (t[6] >> 2) | (t[7] << 3);
k += 5;
}
}
_ => panic!("KYBER_POLYCOMPRESSEDBYTES needs to be one of (128, 160)"),
}
}
pub fn poly_decompress(r: &mut Poly, a: &[u8]) {
match KYBER_POLYCOMPRESSEDBYTES {
128 => {
let mut idx = 0usize;
for i in 0..KYBER_N / 2 {
r.coeffs[2 * i + 0] = ((((a[idx] & 15) as usize * KYBER_Q) + 8) >> 4) as i16;
r.coeffs[2 * i + 1] = ((((a[idx] >> 4) as usize * KYBER_Q) + 8) >> 4) as i16;
idx += 1;
}
}
160 => {
let mut idx = 0usize;
let mut t = [0u8; 8];
for i in 0..KYBER_N / 8 {
t[0] = a[idx + 0];
t[1] = (a[idx + 0] >> 5) | (a[idx + 1] << 3);
t[2] = a[idx + 1] >> 2;
t[3] = (a[idx + 1] >> 7) | (a[idx + 2] << 1);
t[4] = (a[idx + 2] >> 4) | (a[idx + 3] << 4);
t[5] = a[idx + 3] >> 1;
t[6] = (a[idx + 3] >> 6) | (a[idx + 4] << 2);
t[7] = a[idx + 4] >> 3;
idx += 5;
for j in 0..8 {
r.coeffs[8 * i + j] =
((((t[j] as u32) & 31) * KYBER_Q as u32 + 16) >> 5) as i16;
}
}
}
_ => panic!("KYBER_POLYCOMPRESSEDBYTES needs to be either (128, 160)"),
}
}
pub fn poly_tobytes(r: &mut [u8], a: Poly) {
let (mut t0, mut t1);
for i in 0..(KYBER_N / 2) {
t0 = a.coeffs[2 * i];
t0 += (t0 >> 15) & KYBER_Q as i16;
t1 = a.coeffs[2 * i + 1];
t1 += (t1 >> 15) & KYBER_Q as i16;
r[3 * i + 0] = (t0 >> 0) as u8;
r[3 * i + 1] = ((t0 >> 8) | (t1 << 4)) as u8;
r[3 * i + 2] = (t1 >> 4) as u8;
}
}
pub fn poly_frombytes(r: &mut Poly, a: &[u8]) {
for i in 0..(KYBER_N / 2) {
r.coeffs[2 * i + 0] =
((a[3 * i + 0] >> 0) as u16 | ((a[3 * i + 1] as u16) << 8) & 0xFFF) as i16;
r.coeffs[2 * i + 1] =
((a[3 * i + 1] >> 4) as u16 | ((a[3 * i + 2] as u16) << 4) & 0xFFF) as i16;
}
}
pub fn poly_getnoise_eta1(r: &mut Poly, seed: &[u8], nonce: u8) {
const LENGTH: usize = KYBER_ETA1 * KYBER_N / 4;
let mut buf = [0u8; LENGTH];
prf(&mut buf, LENGTH, seed, nonce);
poly_cbd_eta1(r, &buf);
}
pub fn poly_getnoise_eta2(r: &mut Poly, seed: &[u8], nonce: u8) {
const LENGTH: usize = KYBER_ETA2 * KYBER_N / 4;
let mut buf = [0u8; LENGTH];
prf(&mut buf, LENGTH, seed, nonce);
poly_cbd_eta2(r, &buf);
}
pub fn poly_ntt(r: &mut Poly) {
ntt(&mut r.coeffs);
poly_reduce(r);
}
pub fn poly_invntt_tomont(r: &mut Poly) {
invntt(&mut r.coeffs);
}
pub fn poly_basemul(r: &mut Poly, a: &Poly, b: &Poly) {
for i in 0..(KYBER_N / 4) {
basemul(
&mut r.coeffs[4 * i..],
&a.coeffs[4 * i..],
&b.coeffs[4 * i..],
ZETAS[64 + i],
);
basemul(
&mut r.coeffs[4 * i + 2..],
&a.coeffs[4 * i + 2..],
&b.coeffs[4 * i + 2..],
-(ZETAS[64 + i]),
);
}
}
pub fn poly_frommont(r: &mut Poly) {
let f = ((1u64 << 32) % KYBER_Q as u64) as i16;
for i in 0..KYBER_N {
let a = r.coeffs[i] as i32 * f as i32;
r.coeffs[i] = montgomery_reduce(a);
}
}
pub fn poly_reduce(r: &mut Poly) {
for i in 0..KYBER_N {
r.coeffs[i] = barrett_reduce(r.coeffs[i]);
}
}
pub fn poly_add(r: &mut Poly, b: &Poly) {
for i in 0..KYBER_N {
r.coeffs[i] += b.coeffs[i];
}
}
pub fn poly_sub(r: &mut Poly, a: &Poly) {
for i in 0..KYBER_N {
r.coeffs[i] = a.coeffs[i] - r.coeffs[i];
}
}
pub fn poly_frommsg(r: &mut Poly, msg: &[u8]) {
let mut mask;
for i in 0..KYBER_SYMBYTES {
for j in 0..8 {
mask = ((msg[i] as u16 >> j) & 1).wrapping_neg();
r.coeffs[8 * i + j] = (mask & ((KYBER_Q + 1) / 2) as u16) as i16;
}
}
}
pub fn poly_tomsg(msg: &mut [u8], a: Poly) {
let mut t;
for i in 0..KYBER_SYMBYTES {
msg[i] = 0;
for j in 0..8 {
t = a.coeffs[8 * i + j];
t += (t >> 15) & KYBER_Q as i16;
t = (((t << 1) + KYBER_Q as i16 / 2) / KYBER_Q as i16) & 1;
msg[i] |= (t << j) as u8;
}
}
}