From f968f200aae05cfc536b34526412b51ba33f88ba Mon Sep 17 00:00:00 2001
From: Denis Varlakov <denis@dfns.co>
Date: Mon, 8 Jul 2024 10:20:22 +0200
Subject: [PATCH] Use `Reduce<64>` trait

Signed-off-by: Denis Varlakov <denis@dfns.co>
---
 Cargo.lock                       |  2 --
 givre/Cargo.toml                 |  5 +----
 givre/src/ciphersuite/ed25519.rs | 17 +++--------------
 3 files changed, 4 insertions(+), 20 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index fff3121..e1d1075 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -548,11 +548,9 @@ name = "givre"
 version = "0.1.0"
 dependencies = [
  "cggmp21-keygen",
- "curve25519-dalek",
  "digest",
  "futures",
  "generic-ec",
- "generic-ec-curves",
  "k256",
  "key-share",
  "rand_core",
diff --git a/givre/Cargo.toml b/givre/Cargo.toml
index 64fc25b..224fe24 100644
--- a/givre/Cargo.toml
+++ b/givre/Cargo.toml
@@ -10,7 +10,6 @@ cggmp21-keygen = { version = "0.3", optional = true }
 key-share = { version = "0.4", default-features = false }
 
 generic-ec = { version = "0.4", default-features = false, features = ["alloc"] }
-generic-ec-curves = { version = "0.2", default-features = false, optional = true }
 
 rand_core = { version = "0.6", default-features = false }
 digest = { version = "0.10", default-features = false }
@@ -23,8 +22,6 @@ sha2 = { version = "0.10", default-features = false, optional = true }
 
 serde = { version = "1", default-features = false, features = ["derive"], optional = true }
 
-curve25519-dalek = { version = "4", default-features = false, optional = true }
-
 [dev-dependencies]
 rand_core = { version = "0.6", default-features = false, features = ["getrandom"] }
 futures = "0.3"
@@ -50,6 +47,6 @@ hd-wallets = ["key-share/hd-wallets", "cggmp21-keygen?/hd-wallets"]
 
 all-ciphersuites = ["ciphersuite-secp256k1", "ciphersuite-ed25519", "ciphersuite-bitcoin"]
 ciphersuite-secp256k1 = ["generic-ec/curve-secp256k1", "k256", "sha2", "static_assertions"]
-ciphersuite-ed25519 = ["generic-ec/curve-ed25519", "sha2", "curve25519-dalek", "generic-ec-curves/ed25519"]
+ciphersuite-ed25519 = ["generic-ec/curve-ed25519", "sha2"]
 ciphersuite-bitcoin = ["ciphersuite-secp256k1"]
 
diff --git a/givre/src/ciphersuite/ed25519.rs b/givre/src/ciphersuite/ed25519.rs
index 458526c..8cb7df3 100644
--- a/givre/src/ciphersuite/ed25519.rs
+++ b/givre/src/ciphersuite/ed25519.rs
@@ -23,7 +23,7 @@ impl Ciphersuite for Ed25519 {
         }
         let hash = hash.finalize();
 
-        reduce_512bits_le_scalar_mod_order(&hash.into())
+        generic_ec::traits::Reduce::<64>::from_le_array_mod_order(&hash.into())
     }
 
     fn compute_challenge(
@@ -37,7 +37,7 @@ impl Ciphersuite for Ed25519 {
             .chain_update(msg)
             .finalize();
 
-        reduce_512bits_le_scalar_mod_order(&hash.into())
+        generic_ec::traits::Reduce::<64>::from_le_array_mod_order(&hash.into())
     }
 
     fn h3(msg: &[&[u8]]) -> generic_ec::Scalar<Self::Curve> {
@@ -49,7 +49,7 @@ impl Ciphersuite for Ed25519 {
         }
         let hash = hash.finalize();
 
-        reduce_512bits_le_scalar_mod_order(&hash.into())
+        generic_ec::traits::Reduce::<64>::from_le_array_mod_order(&hash.into())
     }
 
     fn h4() -> Self::Digest {
@@ -100,14 +100,3 @@ impl Ciphersuite for Ed25519 {
         Ok(Self::normalize_point(point))
     }
 }
-
-/// Reduces 512 bits integer mod curve order
-///
-/// This is a more efficient version of [`generic_ec::Scalar::from_le_bytes_mod_order`]
-fn reduce_512bits_le_scalar_mod_order(
-    bytes: &[u8; 64],
-) -> generic_ec::Scalar<generic_ec::curves::Ed25519> {
-    let out = curve25519_dalek::Scalar::from_bytes_mod_order_wide(bytes);
-    let out = generic_ec_curves::ed25519::Scalar(out);
-    generic_ec::as_raw::FromRaw::from_raw(out)
-}