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Mitigate kyberslash with official patching method from pq-crystals/kyber #110

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Mitigate kyberslash with official patching method from pq-crystals/kyber #110

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28 changes: 22 additions & 6 deletions src/reference/poly.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,7 @@ pub fn poly_compress(r: &mut [u8], a: Poly) {
let mut t = [0u8; 8];
let mut k = 0usize;
let mut u: i16;
let mut d0: u32;

match KYBER_POLYCOMPRESSEDBYTES {
128 => {
Expand All @@ -40,7 +41,12 @@ pub fn poly_compress(r: &mut [u8], a: Poly) {
// map to positive standard representatives
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;
/* t[j] = (((((u as u16) << 4) + KYBER_Q as u16 / 2) / KYBER_Q as u16) & 15) as u8; */
d0 = ((u as u16) << 4) as u32;
d0 = d0.wrapping_add(1665);
d0 = d0.wrapping_mul(80635);
d0 >>= 28;
t[j] = (d0 & 0xf) as u8;
}
r[k] = t[0] | (t[1] << 4);
r[k + 1] = t[2] | (t[3] << 4);
Expand All @@ -55,7 +61,12 @@ pub fn poly_compress(r: &mut [u8], a: Poly) {
// map to positive standard representatives
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;
/* t[j] = (((((u as u32) << 5) + KYBER_Q as u32 / 2) / KYBER_Q as u32) & 31) as u8; */
d0 = ((u as u32) << 5) as u32;
d0 = d0.wrapping_add(1664);
d0 = d0.wrapping_mul(40318);
d0 >>= 27;
t[j] = (d0 & 0x1f) as u8;
}
r[k] = t[0] | (t[1] << 5);
r[k + 1] = (t[1] >> 3) | (t[2] << 2) | (t[3] << 7);
Expand Down Expand Up @@ -300,14 +311,19 @@ pub fn poly_frommsg(r: &mut Poly, msg: &[u8]) {
/// Arguments: - [u8] msg: output message
/// - const poly *a: input polynomial
pub fn poly_tomsg(msg: &mut [u8], a: Poly) {
let mut t;
let mut t: u32;

for i in 0..KYBER_N / 8 {
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;
t = a.coeffs[8 * i + j] as u32;
// t += (t >> 15) & KYBER_Q as i16;
// t = (((t << 1) + KYBER_Q as i16 / 2) / KYBER_Q as i16) & 1;
t <<= 1;
t = t.wrapping_add(1665);
t = t.wrapping_mul(80635);
t >>= 28;
t &= 1;
msg[i] |= (t << j) as u8;
}
}
Expand Down
20 changes: 16 additions & 4 deletions src/reference/polyvec.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -25,15 +25,21 @@ impl Polyvec {
pub fn polyvec_compress(r: &mut [u8], a: Polyvec) {
#[cfg(feature = "kyber1024")]
{
let mut d0: u64;
let mut t = [0u16; 8];
let mut idx = 0usize;
for i in 0..KYBER_K {
for j in 0..KYBER_N / 8 {
for k in 0..8 {
t[k] = a.vec[i].coeffs[8 * j + k] as u16;
t[k] = t[k].wrapping_add((((t[k] as i16) >> 15) & KYBER_Q as i16) as u16);
t[k] = (((((t[k] as u32) << 11) + KYBER_Q as u32 / 2) / KYBER_Q as u32) & 0x7ff)
as u16;
/*t[k] = (((((t[k] as u32) << 11) + KYBER_Q as u32 / 2) / KYBER_Q as u32) & 0x7ff) as u16; */
d0 = t[k] as u64;
d0 <<= 11;
d0 = d0.wrapping_add(1664);
d0 = d0.wrapping_mul(645084);
d0 >>= 31;
t[k] = (d0 & 0x7ff) as u16;
}
r[idx + 0] = (t[0] >> 0) as u8;
r[idx + 1] = ((t[0] >> 8) | (t[1] << 3)) as u8;
Expand All @@ -53,15 +59,21 @@ pub fn polyvec_compress(r: &mut [u8], a: Polyvec) {

#[cfg(not(feature = "kyber1024"))]
{
let mut d0: u64;
let mut t = [0u16; 4];
let mut idx = 0usize;
for i in 0..KYBER_K {
for j in 0..KYBER_N / 4 {
for k in 0..4 {
t[k] = a.vec[i].coeffs[4 * j + k] as u16;
t[k] = t[k].wrapping_add((((t[k] as i16) >> 15) & KYBER_Q as i16) as u16);
t[k] = (((((t[k] as u32) << 10) + KYBER_Q as u32 / 2) / KYBER_Q as u32) & 0x3ff)
as u16;
/* t[k] = (((((t[k] as u32) << 10) + KYBER_Q as u32 / 2) / KYBER_Q as u32) & 0x3ff) as u16; */
d0 = t[k] as u64;
d0 <<= 10;
d0 = d0.wrapping_add(1665);
d0 = d0.wrapping_mul(1290167);
d0 >>= 32;
t[k] = (d0 & 0x3ff) as u16;
}
r[idx + 0] = (t[0] >> 0) as u8;
r[idx + 1] = ((t[0] >> 8) | (t[1] << 2)) as u8;
Expand Down