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Shift fe_mul to normal Rust multiplication operations.

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This commit is contained in:
Adam Wick
2019-05-25 16:37:04 -07:00
parent 16cf6172ce
commit 25746af626
2 changed files with 290 additions and 314 deletions
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94
src/ed25519/point.rs
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@@ -48,39 +48,30 @@ impl Point {
let hy = FieldElement::from_bytes(s);
let hz = FieldElement::one();
fe_square(&mut u, &hy);
fe_mul(&mut v, &u, &D);
v = &u * &D;
temp = u.clone();
u = &temp - &hz; /* u = y^2-1 */
v += &hz;
fe_square(&mut v3, &v);
temp = v3.clone();
fe_mul(&mut v3, &temp, &v); /* v3 = v^3 */
v3 *= &v; /* v3 = v^3 */
let mut hx = FieldElement::zero();
fe_square(&mut hx, &v3);
temp = hx.clone();
fe_mul(&mut hx, &temp, &v);
temp = hx.clone();
fe_mul(&mut hx, &temp, &u); /* x = uv^7 */
temp = hx.clone();
fe_pow22523(&mut hx, &temp); /* x = (uv^7)^((q-5)/8) */
temp = hx.clone();
fe_mul(&mut hx, &temp, &v3);
temp = hx.clone();
fe_mul(&mut hx, &temp, &u); /* x = uv^3(uv^7)^((q-5)/8) */
hx *= &v;
hx *= &u; /* x = uv^7 */
hx = fe_pow22523(&hx); /* x = (uv^7)^((q-5)/8) */
hx *= &v3;
hx *= &u; /* x = uv^3(uv^7)^((q-5)/8) */
fe_square(&mut vxx, &hx);
temp = vxx.clone();
fe_mul(&mut vxx, &temp, &v);
vxx *= &v;
let mut check = &vxx - &u; /* vx^2-u */
if fe_isnonzero(&check) {
check = &vxx + &u;
if fe_isnonzero(&check) {
return None;
}
temp = hx.clone();
fe_mul(&mut hx, &temp, &SQRTM1);
hx *= &SQRTM1;
}
if fe_isnegative(&hx) != ((s[31] >> 7) == 1) {
@@ -88,8 +79,7 @@ impl Point {
fe_neg(&mut hx, &temp);
}
let mut ht = FieldElement::zero();
fe_mul(&mut ht, &hx, &hy);
let ht = &hx * &hy;
return Some(Point{ x: hx, y: hy, z: hz, t: ht });
}
@@ -264,24 +254,24 @@ fn x25519_ge_p3_to_cached(r: &mut Cached, p: &Point)
r.yplusx = &p.y + &p.x;
r.yminusx = &p.y - &p.x;
r.z.overwrite_with(&p.z);
fe_mul(&mut r.t2d, &p.t, &D2);
r.t2d = &p.t * &D2;
}
/* r = p */
fn x25519_ge_p1p1_to_p2(r: &mut Point2, p: &PointP1P1)
{
fe_mul(&mut r.x, &p.x, &p.t);
fe_mul(&mut r.y, &p.y, &p.z);
fe_mul(&mut r.z, &p.z, &p.t);
r.x = &p.x * &p.t;
r.y = &p.y * &p.z;
r.z = &p.z * &p.t;
}
/* r = p */
fn x25519_ge_p1p1_to_p3(r: &mut Point, p: &PointP1P1)
{
fe_mul(&mut r.x, &p.x, &p.t);
fe_mul(&mut r.y, &p.y, &p.z);
fe_mul(&mut r.z, &p.z, &p.t);
fe_mul(&mut r.t, &p.x, &p.y);
r.x = &p.x * &p.t;
r.y = &p.y * &p.z;
r.z = &p.z * &p.t;
r.t = &p.x * &p.y;
}
#[cfg(test)]
@@ -380,10 +370,9 @@ fn ge_madd(r: &mut PointP1P1, p: &Point, q: &Precomp)
{
r.x = &p.y + &p.x;
r.y = &p.y - &p.x;
fe_mul(&mut r.z, &r.x, &q.yplusx);
let temp = r.y.clone();
fe_mul(&mut r.y, &temp, &q.yminusx);
fe_mul(&mut r.t, &q.xy2d, &p.t);
r.z = &r.x * &q.yplusx;
r.y *= &q.yminusx;
r.t = &q.xy2d * &p.t;
let t0 = &p.z + &p.z;
r.x = &r.z - &r.y;
r.y += &r.z;
@@ -396,10 +385,9 @@ fn ge_msub(r: &mut PointP1P1, p: &Point, q: &Precomp)
{
r.x = &p.y + &p.x;
r.y = &p.y - &p.x;
fe_mul(&mut r.z, &r.x, &q.yminusx);
let temp = r.y.clone();
fe_mul(&mut r.y, &temp, &q.yplusx);
fe_mul(&mut r.t, &q.xy2d, &p.t);
r.z = &r.x * &q.yminusx;
r.y *= &q.yplusx;
r.t = &q.xy2d * &p.t;
let t0 = &p.z + &p.z;
r.x = &r.z - &r.y;
r.y += &r.z;
@@ -436,18 +424,15 @@ fn x25519_ge_add(r: &mut PointP1P1, p: &Point, q: &Cached)
{
r.x = &p.y + &p.x;
r.y = &p.y - &p.x;
fe_mul(&mut r.z, &r.x, &q.yplusx);
let mut temp = r.y.clone();
fe_mul(&mut r.y, &temp, &q.yminusx);
fe_mul(&mut r.t, &q.t2d, &p.t);
fe_mul(&mut r.x, &p.z, &q.z);
r.z = &r.x * &q.yplusx;
r.y *= &q.yminusx;
r.t = &q.t2d * &p.t;
r.x = &p.z * &q.z;
let t0 = &r.x + &r.x;
r.x = &r.z - &r.y;
temp = r.y.clone();
r.y = &r.z + &temp;
r.y += &r.z;
r.z = &t0 + &r.t;
temp = r.t.clone();
r.t = &t0 - &temp;
r.t = &t0 - &r.t;
}
/* r = p - q */
@@ -455,18 +440,15 @@ fn x25519_ge_sub(r: &mut PointP1P1, p: &Point, q: &Cached)
{
r.x = &p.y + &p.x;
r.y = &p.y - &p.x;
fe_mul(&mut r.z, &r.x, &q.yminusx);
let mut temp = r.y.clone();
fe_mul(&mut r.y, &temp, &q.yplusx);
fe_mul(&mut r.t, &q.t2d, &p.t);
fe_mul(&mut r.x, &p.z, &q.z);
r.z = &r.x * &q.yminusx;
r.y *= &q.yplusx;
r.t = &q.t2d * &p.t;
r.x = &p.z * &q.z;
let t0 = &r.x + &r.x;
r.x = &r.z - &r.y;
temp = r.y.clone();
r.y = &r.z + &temp;
r.y += &r.z;
r.z = &t0 - &r.t;
temp = r.t.clone();
r.t = &t0 + &temp;
r.t += &t0;
}
#[cfg(test)]
@@ -1826,8 +1808,8 @@ fn into_encoded_point(x: &FieldElement, y: &FieldElement, z: &FieldElement) -> V
let mut y_over_z = FieldElement::new();
let recip = fe_invert(z);
fe_mul(&mut x_over_z, x, &recip);
fe_mul(&mut y_over_z, y, &recip);
x_over_z = x * &recip;
y_over_z = y * &recip;
let mut bytes = y_over_z.to_bytes();
let sign_bit = if fe_isnegative(&x_over_z) { 1 } else { 0 };
// The preceding computations must execute in constant time, but this