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Switch to Add/Sub impls.

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This commit is contained in:
Adam Wick
2019-05-26 15:59:04 -07:00
parent b0885722a8
commit 7f2b509640
1 changed files with 113 additions and 85 deletions
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198
src/ed25519/point.rs
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@@ -3,6 +3,7 @@ use testing::run_test;
use ed25519::fe::*;
use ed25519::constants::*;
use std::ops::*;
// This is ge_p3 in the original source code
#[derive(Clone,Debug,PartialEq)]
@@ -160,7 +161,7 @@ impl<'a> From<&'a Point> for Point2 {
}
#[derive(Debug,PartialEq)]
struct PointP1P1 {
pub struct PointP1P1 {
x: FieldElement,
y: FieldElement,
z: FieldElement,
@@ -168,16 +169,6 @@ struct PointP1P1 {
}
impl PointP1P1 {
fn new() -> PointP1P1
{
PointP1P1 {
x: FieldElement::new(),
y: FieldElement::new(),
z: FieldElement::new(),
t: FieldElement::new(),
}
}
#[cfg(test)]
fn load_test_value(xs: &[u8]) -> PointP1P1 {
assert!(xs.len() == 160);
@@ -350,34 +341,51 @@ fn double() {
});
}
/* r = p + q */
fn ge_madd(r: &mut PointP1P1, p: &Point, q: &Precomp)
impl<'a,'b> Add<&'a Precomp> for &'b Point
{
r.x = &p.y + &p.x;
r.y = &p.y - &p.x;
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;
r.z = &t0 + &r.t;
r.t = &t0 - &r.t;
type Output = PointP1P1;
fn add(self, q: &Precomp) -> PointP1P1
{
let mut rx;
let mut ry;
let mut rz;
let mut rt;
rx = &self.y + &self.x;
ry = &self.y - &self.x;
rz = &rx * &q.yplusx;
ry *= &q.yminusx;
rt = &q.xy2d * &self.t;
let t0 = &self.z + &self.z;
rx = &rz - &ry;
ry += &rz;
rz = &t0 + &rt;
rt = &t0 - &rt;
PointP1P1 { x: rx, y: ry, z: rz, t: rt }
}
}
/* r = p - q */
fn ge_msub(r: &mut PointP1P1, p: &Point, q: &Precomp)
impl<'a,'b> Sub<&'a Precomp> for &'b Point
{
r.x = &p.y + &p.x;
r.y = &p.y - &p.x;
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;
r.z = &t0 - &r.t;
r.t += &t0;
type Output = PointP1P1;
/* r = p - q */
fn sub(self, q: &Precomp) -> PointP1P1
{
let mut rx = &self.y + &self.x;
let mut ry = &self.y - &self.x;
let mut rz = &rx * &q.yminusx;
ry *= &q.yplusx;
let mut rt = &q.xy2d * &self.t;
let t0 = &self.z + &self.z;
rx = &rz - &ry;
ry += &rz;
rz = &t0 - &rt;
rt += &t0;
PointP1P1{ x: rx, y: ry, z: rz, t: rt }
}
}
#[cfg(test)]
@@ -396,44 +404,65 @@ fn maddsub() {
let c = Precomp::load_test_value(cbytes);
let d = PointP1P1::load_test_value(dbytes);
let mut mine = PointP1P1::new();
ge_madd(&mut mine, &a, &c);
assert_eq!(mine, b);
ge_msub(&mut mine, &a, &c);
assert_eq!(mine, d);
let myb = &a + &c;
assert_eq!(myb, b);
let myd = &a - &c;
assert_eq!(myd, d);
});
}
/* r = p + q */
fn x25519_ge_add(r: &mut PointP1P1, p: &Point, q: &Cached)
impl<'a,'b> Add<&'a Cached> for &'b Point
{
r.x = &p.y + &p.x;
r.y = &p.y - &p.x;
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;
r.y += &r.z;
r.z = &t0 + &r.t;
r.t = &t0 - &r.t;
type Output = PointP1P1;
fn add(self, q: &Cached) -> PointP1P1
{
let mut rx;
let mut ry;
let mut rz;
let mut rt;
rx = &self.y + &self.x;
ry = &self.y - &self.x;
rz = &rx * &q.yplusx;
ry *= &q.yminusx;
rt = &q.t2d * &self.t;
rx = &self.z * &q.z;
let t0 = &rx + &rx;
rx = &rz - &ry;
ry += &rz;
rz = &t0 + &rt;
rt = &t0 - &rt;
PointP1P1{ x: rx, y: ry, z: rz, t: rt }
}
}
/* r = p - q */
fn x25519_ge_sub(r: &mut PointP1P1, p: &Point, q: &Cached)
impl<'a,'b> Sub<&'a Cached> for &'b Point
{
r.x = &p.y + &p.x;
r.y = &p.y - &p.x;
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;
r.y += &r.z;
r.z = &t0 - &r.t;
r.t += &t0;
type Output = PointP1P1;
fn sub(self, q: &Cached) -> PointP1P1
{
let mut rx;
let mut ry;
let mut rz;
let mut rt;
rx = &self.y + &self.x;
ry = &self.y - &self.x;
rz = &rx * &q.yminusx;
ry *= &q.yplusx;
rt = &q.t2d * &self.t;
rx = &self.z * &q.z;
let t0 = &rx + &rx;
rx = &rz - &ry;
ry += &rz;
rz = &t0 - &rt;
rt += &t0;
PointP1P1{ x: rx, y: ry, z: rz, t: rt }
}
}
#[cfg(test)]
@@ -452,11 +481,10 @@ fn addsub() {
let c = Cached::load_test_value(cbytes);
let d = PointP1P1::load_test_value(dbytes);
let mut mine = PointP1P1::new();
x25519_ge_add(&mut mine, &a, &c);
assert_eq!(mine, b);
x25519_ge_sub(&mut mine, &a, &c);
assert_eq!(mine, d);
let myb = &a + &c;
assert_eq!(myb, b);
let myd = &a - &c;
assert_eq!(myd, d);
});
}
@@ -524,13 +552,13 @@ impl Point {
e[63] += carry;
/* each e[i] is between -8 and 8 */
let mut r = PointP1P1::new();
let mut r;
let mut t;
let mut h = Point::zero();
for i in &[1,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33,35,37,39,41,43,45,47,49,51,53,55,57,59,61,63] {
t = table_select(*i / 2, e[*i as usize]);
ge_madd(&mut r, &h, &t);
r = &h + &t;
h = Point::from(&r);
}
@@ -545,7 +573,7 @@ impl Point {
for i in &[0,2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,32,34,36,38,40,42,44,46,48,50,52,54,56,58,60,62] {
t = table_select(*i / 2, e[*i as usize]);
ge_madd(&mut r, &h, &t);
r = &h + &t;
h = Point::from(&r);
}
@@ -638,25 +666,25 @@ pub fn ge_double_scalarmult_vartime(a: &[u8], A: &Point, b: &[u8]) -> Point2
Ai[0] = Cached::from(A);
let mut t = A.double();
let A2 = Point::from(&t);
x25519_ge_add(&mut t, &A2, &Ai[0]);
t = &A2 + &Ai[0];
let mut u = Point::from(&t);
Ai[1] = Cached::from(&u);
x25519_ge_add(&mut t, &A2, &Ai[1]);
t = &A2 + &Ai[1];
u = Point::from(&t);
Ai[2] = Cached::from(&u);
x25519_ge_add(&mut t, &A2, &Ai[2]);
t = &A2 + &Ai[2];
u = Point::from(&t);
Ai[3] = Cached::from(&u);
x25519_ge_add(&mut t, &A2, &Ai[3]);
t = &A2 + &Ai[3];
u = Point::from(&t);
Ai[4] = Cached::from(&u);
x25519_ge_add(&mut t, &A2, &Ai[4]);
t = &A2 + &Ai[4];
u = Point::from(&t);
Ai[5] = Cached::from(&u);
x25519_ge_add(&mut t, &A2, &Ai[5]);
t = &A2 + &Ai[5];
u = Point::from(&t);
Ai[6] = Cached::from(&u);
x25519_ge_add(&mut t, &A2, &Ai[6]);
t = &A2 + &Ai[6];
u = Point::from(&t);
Ai[7] = Cached::from(&u);
@@ -679,21 +707,21 @@ pub fn ge_double_scalarmult_vartime(a: &[u8], A: &Point, b: &[u8]) -> Point2
if aslide[i as usize] > 0 {
u = Point::from(&t);
let idx = (aslide[i as usize] / 2) as usize;
x25519_ge_add(&mut t, &u, &Ai[idx]);
t = &u + &Ai[idx]
} else if aslide[i as usize] < 0 {
u = Point::from(&t);
let idx = ((-aslide[i as usize]) / 2) as usize;
x25519_ge_sub(&mut t, &u, &Ai[idx]);
t = &u - &Ai[idx];
}
if bslide[i as usize] > 0 {
u = Point::from(&t);
let idx = (bslide[i as usize] / 2) as usize;
ge_madd(&mut t, &u, &BI[idx]);
t = &u + &BI[idx];
} else if bslide[i as usize] < 0 {
u = Point::from(&t);
let idx = ((-bslide[i as usize]) / 2) as usize;
ge_msub(&mut t, &u, &BI[idx]);
t = &u - &BI[idx];
}
r = Point2::from(&t);