ecdsa: use new Reduce trait (#1030)

Uses the `Reduce` trait added in RustCrypto/traits#1949

Cargo.lock

@@ -261,9 +261,9 @@ checksum = "43da5946c66ffcc7745f48db692ffbb10a83bfe0afd96235c5c2a4fb23994929"
 
 [[package]]
 name = "crypto-bigint"
-version = "0.7.0-pre.7"
+version = "0.7.0-rc.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "85ff38607b7ebe30e4715eeb0a0427ff42e3b6b47b2df55a775e767ef2658ccd"
+checksum = "737a2363b81de8cc95d8780d84aecb4b3c6f41e4473759da6636072b5514c875"
 dependencies = [
  "hybrid-array",
  "num-traits",
@@ -409,8 +409,8 @@ checksum = "48c757948c5ede0e46177b7add2e67155f70e33c07fea8284df6576da70b3719"
 
 [[package]]
 name = "elliptic-curve"
-version = "0.14.0-rc.10"
-source = "git+https://github.com/RustCrypto/traits#a10ef181945a480bba5d2fb36ad6f3f78a3474db"
+version = "0.14.0-rc.11"
+source = "git+https://github.com/RustCrypto/traits#526970708925a6030483d55fb00e62a9781505b4"
 dependencies = [
  "base16ct",
  "crypto-bigint",

dsa/Cargo.toml

@@ -18,7 +18,7 @@ rust-version = "1.85"
 [dependencies]
 der = { version = "0.8.0-rc.7", features = ["alloc"] }
 digest = "0.11.0-rc.0"
-crypto-bigint = { version = "=0.7.0-pre.7", default-features = false, features = ["alloc", "zeroize"] }
+crypto-bigint = { version = "0.7.0-rc.0", default-features = false, features = ["alloc", "zeroize"] }
 crypto-primes = { version = "=0.7.0-pre.1", default-features = false }
 rfc6979 = { version = "0.5.0-rc.0" }
 sha2 = { version = "0.11.0-rc.0", default-features = false }

ecdsa/src/hazmat.rs

@@ -113,7 +113,7 @@ where
     C: EcdsaCurve + CurveArithmetic,
     SignatureSize<C>: ArraySize,
 {
-    let z = <Scalar<C> as Reduce<C::Uint>>::reduce_bytes(z);
+    let z = Scalar::<C>::reduce(z);
 
     // Compute scalar inversion of 𝑘.
     let k_inv = k.invert();
@@ -123,7 +123,7 @@ where
 
     // Lift x-coordinate of 𝑹 (element of base field) into a serialized big
     // integer, then reduce it into an element of the scalar field.
-    let r = Scalar::<C>::reduce_bytes(&R.x());
+    let r = Scalar::<C>::reduce(&R.x());
 
     // Compute 𝒔 as a signature over 𝒓 and 𝒛.
     let s = *k_inv * (z + (r * d.as_ref()));
@@ -176,7 +176,7 @@ where
     // transform and an extra modular reduction:
     //
     // h = bits2int(H(m)) mod q
-    let z2 = <Scalar<C> as Reduce<C::Uint>>::reduce_bytes(z);
+    let z2 = Scalar::<C>::reduce(z);
 
     let k = NonZeroScalar::<C>::from_repr(rfc6979::generate_k::<D, _>(
         &d.to_repr(),
@@ -211,7 +211,7 @@ where
     C: EcdsaCurve + CurveArithmetic,
     SignatureSize<C>: ArraySize,
 {
-    let z = Scalar::<C>::reduce_bytes(z);
+    let z = Scalar::<C>::reduce(z);
     let (r, s) = sig.split_scalars();
     let s_inv = *s.invert_vartime();
     let u1 = z * s_inv;
@@ -220,7 +220,7 @@ where
         .to_affine()
         .x();
 
-    if *r == Scalar::<C>::reduce_bytes(&x) {
+    if *r == Scalar::<C>::reduce(&x) {
         Ok(())
     } else {
         Err(Error::new())

ecdsa/src/recovery.rs

@@ -373,7 +373,7 @@ where
         recovery_id: RecoveryId,
     ) -> Result<Self> {
         let (r, s) = signature.split_scalars();
-        let z = <Scalar<C> as Reduce<C::Uint>>::reduce_bytes(&bits2field::<C>(prehash)?);
+        let z = Scalar::<C>::reduce(&bits2field::<C>(prehash)?);
 
         let r_bytes = if recovery_id.is_x_reduced() {
             Option::<C::Uint>::from(