ConstantTimeEq and PartialEq for SigningKey

Author: mkj

Cargo.lock

@@ -29,6 +29,7 @@ curve25519-dalek = { version = "=4.0.0-rc.2", default-features = false, features
 ed25519 = { version = ">=2.2, <2.3", default-features = false }
 signature = { version = ">=2.0, <2.1", optional = true, default-features = false }
 sha2 = { version = "0.10", default-features = false }
+subtle = { version = "2.3.0", default-features = false }
 
 # optional features
 merlin = { version = "3", default-features = false, optional = true }

Cargo.toml

@@ -19,6 +19,7 @@ use rand_core::CryptoRngCore;
 use serde::{Deserialize, Deserializer, Serialize, Serializer};
 
 use sha2::Sha512;
+use subtle::{Choice, ConstantTimeEq};
 
 use curve25519_dalek::{
     digest::{generic_array::typenum::U64, Digest},
@@ -583,6 +584,20 @@ impl TryFrom<&[u8]> for SigningKey {
     }
 }
 
+impl ConstantTimeEq for SigningKey {
+    fn ct_eq(&self, other: &Self) -> Choice {
+        self.secret_key.ct_eq(&other.secret_key)
+    }
+}
+
+impl PartialEq for SigningKey {
+    fn eq(&self, other: &Self) -> bool {
+        self.ct_eq(other).into()
+    }
+}
+
+impl Eq for SigningKey {}
+
 #[cfg(feature = "zeroize")]
 impl Drop for SigningKey {
     fn drop(&mut self) {