test subtle 2.0

Cargo.toml

@@ -45,7 +45,7 @@ rand = { version = "0.5", default-features = false }
 byteorder = { version = "^1.2.3", default-features = false, features = ["i128"] }
 digest = { version = "0.8", default-features = false }
 clear_on_drop = "=0.2.3"
-subtle = { version = "1", default-features = false }
+subtle = { version = "2", default-features = false }
 serde = { version = "1.0", optional = true }
 packed_simd = { version = "0.3.0", features = ["into_bits"], optional = true }
 
@@ -54,7 +54,7 @@ rand = { version = "0.5", default-features = false }
 byteorder = { version = "^1.2.3", default-features = false, features = ["i128"] }
 digest = { version = "0.8", default-features = false }
 clear_on_drop = "=0.2.3"
-subtle = { version = "1", default-features = false }
+subtle = { version = "2", default-features = false }
 serde = { version = "1.0", optional = true }
 packed_simd = { version = "0.3.0", features = ["into_bits"], optional = true }
 
@@ -78,3 +78,6 @@ avx2_backend = ["nightly", "u64_backend", "packed_simd"]
 # into the build script. Then, the build.rs emits the stage2_build
 # feature before the main-stage compilation.
 stage2_build = []
+
+[patch.crates-io]
+subtle = { git = "https://github.com/dalek-cryptography/subtle", branch = "fix-subtle-traits" }

src/backend/avx2/edwards.rs

@@ -80,6 +80,10 @@ impl ConditionallySelectable for ExtendedPoint {
     fn conditional_select(a: &Self, b: &Self, choice: Choice) -> Self {
         ExtendedPoint(FieldElement32x4::conditional_select(&a.0, &b.0, choice))
     }
+
+    fn conditional_assign(&mut self, other: &Self, choice: Choice) {
+        self.0.conditional_assign(&other.0, choice);
+    }
 }
 
 impl Default for ExtendedPoint {
@@ -213,6 +217,10 @@ impl ConditionallySelectable for CachedPoint {
     fn conditional_select(a: &Self, b: &Self, choice: Choice) -> Self {
         CachedPoint(FieldElement32x4::conditional_select(&a.0, &b.0, choice))
     }
+
+    fn conditional_assign(&mut self, other: &Self, choice: Choice) {
+        self.0.conditional_assign(&other.0, choice);
+    }
 }
 
 impl<'a> Neg for &'a CachedPoint {

src/backend/avx2/field.rs

@@ -155,13 +155,27 @@ impl ConditionallySelectable for FieldElement32x4 {
         let mask = (-(choice.unwrap_u8() as i32)) as u32;
         let mask_vec = u32x8::splat(mask);
         FieldElement32x4([
-            self.0[0] ^ (mask_vec & (self.0[0] ^ other.0[0])),
-            self.0[1] ^ (mask_vec & (self.0[1] ^ other.0[1])),
-            self.0[2] ^ (mask_vec & (self.0[2] ^ other.0[2])),
-            self.0[3] ^ (mask_vec & (self.0[3] ^ other.0[3])),
-            self.0[4] ^ (mask_vec & (self.0[4] ^ other.0[4])),
+            a.0[0] ^ (mask_vec & (a.0[0] ^ b.0[0])),
+            a.0[1] ^ (mask_vec & (a.0[1] ^ b.0[1])),
+            a.0[2] ^ (mask_vec & (a.0[2] ^ b.0[2])),
+            a.0[3] ^ (mask_vec & (a.0[3] ^ b.0[3])),
+            a.0[4] ^ (mask_vec & (a.0[4] ^ b.0[4])),
         ])
     }
+
+    fn conditional_assign(
+        &mut self,
+        other: &FieldElement32x4,
+        choice: Choice,
+    ) {
+        let mask = (-(choice.unwrap_u8() as i32)) as u32;
+        let mask_vec = u32x8::splat(mask);
+        self.0[0] ^= mask_vec & (self.0[0] ^ other.0[0]);
+        self.0[1] ^= mask_vec & (self.0[1] ^ other.0[1]);
+        self.0[2] ^= mask_vec & (self.0[2] ^ other.0[2]);
+        self.0[3] ^= mask_vec & (self.0[3] ^ other.0[3]);
+        self.0[4] ^= mask_vec & (self.0[4] ^ other.0[4]);
+    }
 }
 
 impl FieldElement32x4 {

src/backend/u32/field.rs

@@ -16,13 +16,13 @@
 //! of signed limbs.
 
 use core::fmt::Debug;
-use core::ops::{Add, AddAssign};
-use core::ops::{Sub, SubAssign};
-use core::ops::{Mul, MulAssign};
 use core::ops::Neg;
+use core::ops::{Add, AddAssign};
+use core::ops::{Mul, MulAssign};
+use core::ops::{Sub, SubAssign};
 
-use subtle::ConditionallySelectable;
 use subtle::Choice;
+use subtle::ConditionallySelectable;
 
 /// A `FieldElement32` represents an element of the field
 /// \\( \mathbb Z / (2\^{255} - 19)\\).
@@ -238,6 +238,32 @@ impl ConditionallySelectable for FieldElement32 {
             u32::conditional_select(&a.0[9], &b.0[9], choice),
         ])
     }
+
+    fn conditional_assign(&mut self, other: &FieldElement32, choice: Choice) {
+        self.0[0].conditional_assign(&other.0[0], choice);
+        self.0[1].conditional_assign(&other.0[1], choice);
+        self.0[2].conditional_assign(&other.0[2], choice);
+        self.0[3].conditional_assign(&other.0[3], choice);
+        self.0[4].conditional_assign(&other.0[4], choice);
+        self.0[5].conditional_assign(&other.0[5], choice);
+        self.0[6].conditional_assign(&other.0[6], choice);
+        self.0[7].conditional_assign(&other.0[7], choice);
+        self.0[8].conditional_assign(&other.0[8], choice);
+        self.0[9].conditional_assign(&other.0[9], choice);
+    }
+
+    fn conditional_swap(a: &mut FieldElement32, b: &mut FieldElement32, choice: Choice) {
+        u32::conditional_swap(&mut a.0[0], &mut b.0[0], choice);
+        u32::conditional_swap(&mut a.0[1], &mut b.0[1], choice);
+        u32::conditional_swap(&mut a.0[2], &mut b.0[2], choice);
+        u32::conditional_swap(&mut a.0[3], &mut b.0[3], choice);
+        u32::conditional_swap(&mut a.0[4], &mut b.0[4], choice);
+        u32::conditional_swap(&mut a.0[5], &mut b.0[5], choice);
+        u32::conditional_swap(&mut a.0[6], &mut b.0[6], choice);
+        u32::conditional_swap(&mut a.0[7], &mut b.0[7], choice);
+        u32::conditional_swap(&mut a.0[8], &mut b.0[8], choice);
+        u32::conditional_swap(&mut a.0[9], &mut b.0[9], choice);
+    }
 }
 
 impl FieldElement32 {

src/backend/u64/field.rs

@@ -223,6 +223,22 @@ impl ConditionallySelectable for FieldElement64 {
             u64::conditional_select(&a.0[4], &b.0[4], choice),
         ])
     }
+
+    fn conditional_swap(a: &mut FieldElement64, b: &mut FieldElement64, choice: Choice) {
+        u64::conditional_swap(&mut a.0[0], &mut b.0[0], choice);
+        u64::conditional_swap(&mut a.0[1], &mut b.0[1], choice);
+        u64::conditional_swap(&mut a.0[2], &mut b.0[2], choice);
+        u64::conditional_swap(&mut a.0[3], &mut b.0[3], choice);
+        u64::conditional_swap(&mut a.0[4], &mut b.0[4], choice);
+    }
+
+    fn conditional_assign(&mut self, other: &FieldElement64, choice: Choice) {
+        self.0[0].conditional_assign(&other.0[0], choice);
+        self.0[1].conditional_assign(&other.0[1], choice);
+        self.0[2].conditional_assign(&other.0[2], choice);
+        self.0[3].conditional_assign(&other.0[3], choice);
+        self.0[4].conditional_assign(&other.0[4], choice);
+    }
 }
 
 impl FieldElement64 {

src/curve_models/mod.rs

@@ -277,6 +277,13 @@ impl ConditionallySelectable for ProjectiveNielsPoint {
             T2d: FieldElement::conditional_select(&a.T2d, &b.T2d, choice),
         }
     }
+
+    fn conditional_assign(&mut self, other: &Self, choice: Choice) {
+        self.Y_plus_X.conditional_assign(&other.Y_plus_X, choice);
+        self.Y_minus_X.conditional_assign(&other.Y_minus_X, choice);
+        self.Z.conditional_assign(&other.Z, choice);
+        self.T2d.conditional_assign(&other.T2d, choice);
+    }
 }
 
 impl ConditionallySelectable for AffineNielsPoint {
@@ -287,6 +294,12 @@ impl ConditionallySelectable for AffineNielsPoint {
             xy2d: FieldElement::conditional_select(&a.xy2d, &b.xy2d, choice),
         }
     }
+
+    fn conditional_assign(&mut self, other: &Self, choice: Choice) {
+        self.y_plus_x.conditional_assign(&other.y_plus_x, choice);
+        self.y_minus_x.conditional_assign(&other.y_minus_x, choice);
+        self.xy2d.conditional_assign(&other.xy2d, choice);
+    }
 }
 
 // ------------------------------------------------------------------------

src/edwards.rs

@@ -903,7 +903,7 @@ impl Debug for EdwardsBasepointTable {
 mod test {
     use field::FieldElement;
     use scalar::Scalar;
-    use subtle::ConditionallyAssignable;
+    use subtle::ConditionallySelectable;
     use constants;
     use super::*;
 

src/field.rs

@@ -24,7 +24,7 @@
 
 use core::cmp::{Eq, PartialEq};
 
-use subtle::ConditionallyAssignable;
+use subtle::ConditionallySelectable;
 use subtle::ConditionallyNegatable;
 use subtle::Choice;
 use subtle::ConstantTimeEq;

src/montgomery.rs

@@ -51,15 +51,14 @@
 use core::ops::{Mul, MulAssign};
 
 use constants::APLUS2_OVER_FOUR;
+use edwards::{CompressedEdwardsY, EdwardsPoint};
 use field::FieldElement;
-use edwards::{EdwardsPoint, CompressedEdwardsY};
 use scalar::Scalar;
 
 use traits::Identity;
 
 use subtle::Choice;
 use subtle::ConditionallySelectable;
-use subtle::ConditionallySwappable;
 use subtle::ConstantTimeEq;
 
 /// Holds the \\(u\\)-coordinate of a point on the Montgomery form of
@@ -255,19 +254,22 @@ impl<'a, 'b> Mul<&'b Scalar> for &'a MontgomeryPoint {
         // Algorithm 8 of Costello-Smith 2017
         let affine_u = FieldElement::from_bytes(&self.0);
         let mut x0 = ProjectivePoint::identity();
-        let mut x1 = ProjectivePoint{ U: affine_u, W: FieldElement::one() };
+        let mut x1 = ProjectivePoint {
+            U: affine_u,
+            W: FieldElement::one(),
+        };
 
         let bits: [i8; 256] = scalar.bits();
 
         for i in (0..255).rev() {
-            let choice: u8 = (bits[i+1] ^ bits[i]) as u8;
+            let choice: u8 = (bits[i + 1] ^ bits[i]) as u8;
 
             debug_assert!(choice == 0 || choice == 1);
 
-            x0.conditional_swap(&mut x1, choice.into());
+            ProjectivePoint::conditional_swap(&mut x0, &mut x1, choice.into());
             differential_add_and_double(&mut x0, &mut x1, &affine_u);
         }
-        x0.conditional_swap(&mut x1, Choice::from(bits[0] as u8));
+        ProjectivePoint::conditional_swap(&mut x0, &mut x1, Choice::from(bits[0] as u8));
 
         x0.to_affine()
     }

src/ristretto.rs

@@ -173,9 +173,8 @@ use constants;
 use field::FieldElement;
 
 use subtle::Choice;
-use subtle::ConditionallyAssignable;
-use subtle::ConditionallyNegatable;
 use subtle::ConditionallySelectable;
+use subtle::ConditionallyNegatable;
 use subtle::ConstantTimeEq;
 
 use edwards::EdwardsBasepointTable;

src/scalar.rs

@@ -983,7 +983,7 @@ impl Scalar {
     /// # extern crate curve25519_dalek;
     /// # extern crate subtle;
     /// # use curve25519_dalek::scalar::Scalar;
-    /// # use subtle::ConditionallyAssignable;
+    /// # use subtle::ConditionallySelectable;
     /// # fn main() {
     /// // 2^255 - 1, since `from_bits` clears the high bit
     /// let _2_255_minus_1 = Scalar::from_bits([0xff;32]);

src/scalar_mul/window.rs

@@ -15,7 +15,7 @@
 use core::fmt::Debug;
 
 use subtle::ConditionallyNegatable;
-use subtle::ConditionallyAssignable;
+use subtle::ConditionallySelectable;
 use subtle::ConstantTimeEq;
 use subtle::Choice;
 
@@ -59,7 +59,7 @@ unsafe impl<T> ZeroSafe for LookupTable<T> {}
 
 impl<T> LookupTable<T>
 where
-    T: Identity + ConditionallyAssignable + ConditionallyNegatable,
+    T: Identity + ConditionallySelectable + ConditionallyNegatable,
 {
     /// Given \\(-8 \leq x \leq 8\\), return \\(xP\\) in constant time.
     pub fn select(&self, x: i8) -> T {