Use new Reduce trait (#1359)

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

Author: baloo

Cargo.lock

@@ -21,7 +21,7 @@ members = [
 opt-level = 2
 
 [patch.crates-io]
-crypto-bigint = { git = "https://github.com/RustCrypto/crypto-bigint" }
+ecdsa = { git = "https://github.com/RustCrypto/signatures.git" }
 elliptic-curve = { git = "https://github.com/RustCrypto/traits.git" }
 
 hash2curve = { path = "hash2curve" }

Cargo.toml

@@ -18,7 +18,7 @@ edition = "2024"
 rust-version = "1.85"
 
 [dependencies]
-elliptic-curve = { version = "0.14.0-rc.10", features = ["sec1"] }
+elliptic-curve = { version = "0.14.0-rc.11", features = ["sec1"] }
 
 # optional dependencies
 belt-hash = { version = "0.2.0-rc.0", optional = true, default-features = false }

bign256/Cargo.toml

@@ -168,18 +168,18 @@ impl PrimeFieldBits for Scalar {
 }
 
 impl Reduce<U256> for Scalar {
-    type Bytes = FieldBytes;
-
-    fn reduce(w: U256) -> Self {
+    fn reduce(w: &U256) -> Self {
         let (r, underflow) = w.borrowing_sub(&BignP256::ORDER, Limb::ZERO);
         let underflow = Choice::from((underflow.0 >> (Limb::BITS - 1)) as u8);
-        Self::from_uint_unchecked(U256::conditional_select(&w, &r, !underflow))
+        Self::from_uint_unchecked(U256::conditional_select(w, &r, !underflow))
     }
+}
 
+impl Reduce<FieldBytes> for Scalar {
     #[inline]
-    fn reduce_bytes(bytes: &FieldBytes) -> Self {
+    fn reduce(bytes: &FieldBytes) -> Self {
         let w = <U256 as FieldBytesEncoding<BignP256>>::decode_field_bytes(bytes);
-        Self::reduce(w)
+        Self::reduce(&w)
     }
 }
 

bign256/src/arithmetic/scalar.rs

@@ -109,7 +109,7 @@ impl PrehashSigner<Signature> for SigningKey {
         let mut h_word: Array<u8, U32> = Array::clone_from_slice(prehash);
         h_word.reverse();
 
-        let h = Scalar::reduce_bytes(&h_word);
+        let h = Scalar::reduce(&h_word);
 
         //2. Generate 𝑘 ← rand(1,..,𝑞-1)
         let k = Scalar::from_repr(rfc6979::generate_k::<BeltHash, _>(

bign256/src/ecdsa/signing.rs

@@ -121,7 +121,7 @@ impl PrehashVerifier<Signature> for VerifyingKey {
         let mut hash: Array<u8, U32> = Array::clone_from_slice(prehash);
         hash.reverse();
 
-        let hw = Scalar::reduce_bytes(FieldBytes::from_slice(&hash));
+        let hw = Scalar::reduce(FieldBytes::from_slice(&hash));
         let left = s1.add(&hw);
 
         let right = s0.add(&Scalar::from_u64(2).pow([128, 0, 0, 0]));

bign256/src/ecdsa/verifying.rs

@@ -7,7 +7,7 @@ use hex_literal::hex;
 use proptest::prelude::*;
 
 use bign256::{
-    NonZeroScalar, Scalar, U256,
+    FieldBytes, NonZeroScalar, Scalar,
     ecdsa::{
         Signature, SigningKey, VerifyingKey,
         signature::{Signer, Verifier},
@@ -35,7 +35,7 @@ fn verify_test_vector() {
 prop_compose! {
     fn signing_key()(bytes in any::<[u8; 32]>()) -> SigningKey {
         loop {
-            let scalar = <Scalar as Reduce<U256>>::reduce_bytes(&bytes.into());
+            let scalar = <Scalar as Reduce<FieldBytes>>::reduce(&bytes.into());
             if let Some(scalar) = Option::from(NonZeroScalar::new(scalar)) {
                 return SigningKey::from_nonzero_scalar(scalar).unwrap();
             }

bign256/tests/dsa.rs

@@ -2,13 +2,13 @@
 
 #![cfg(feature = "arithmetic")]
 
-use bign256::{Scalar, U256};
+use bign256::{FieldBytes, Scalar};
 use elliptic_curve::ops::{Invert, Reduce};
 use proptest::prelude::*;
 
 prop_compose! {
     fn scalar()(bytes in any::<[u8; 32]>()) -> Scalar {
-        <Scalar as Reduce<U256>>::reduce_bytes(&bytes.into())
+        <Scalar as Reduce<FieldBytes>>::reduce(&bytes.into())
     }
 }
 

bign256/tests/scalar.rs

@@ -14,7 +14,7 @@ edition = "2024"
 rust-version = "1.85"
 
 [dependencies]
-elliptic-curve = { version = "0.14.0-rc.10", default-features = false, features = ["sec1"] }
+elliptic-curve = { version = "0.14.0-rc.11", default-features = false, features = ["sec1"] }
 
 # optional dependencies
 ecdsa = { version = "0.17.0-rc.4", optional = true, default-features = false, features = ["der"] }

bp256/Cargo.toml

@@ -132,17 +132,17 @@ impl PrimeField for Scalar {
 }
 
 impl Reduce<U256> for Scalar {
-    type Bytes = FieldBytes;
-
-    fn reduce(w: U256) -> Self {
+    fn reduce(w: &U256) -> Self {
         let (r, underflow) = w.borrowing_sub(&ORDER, Limb::ZERO);
         let underflow = Choice::from((underflow.0 >> (Limb::BITS - 1)) as u8);
-        Self::from_uint_unchecked(U256::conditional_select(&w, &r, !underflow))
+        Self::from_uint_unchecked(U256::conditional_select(w, &r, !underflow))
     }
+}
 
+impl Reduce<FieldBytes> for Scalar {
     #[inline]
-    fn reduce_bytes(bytes: &FieldBytes) -> Self {
-        Self::reduce(U256::from_be_byte_array(*bytes))
+    fn reduce(bytes: &FieldBytes) -> Self {
+        Self::reduce(&U256::from_be_byte_array(*bytes))
     }
 }