implement KeySizeUser for SigningKey and VerifyingKey

curve25519-dalek/Cargo.toml

@@ -76,6 +76,7 @@ group = ["dep:group", "rand_core"]
 group-bits = ["group", "ff/bits"]
 digest = ["dep:digest"]
 lizard = ["digest"]
+rand_core = ["dep:rand_core", "digest/rand_core"]
 
 [target.'cfg(all(not(curve25519_dalek_backend = "fiat"), not(curve25519_dalek_backend = "serial"), target_arch = "x86_64"))'.dependencies]
 curve25519-dalek-derive = "0.1"

ed25519-dalek/Cargo.toml

@@ -87,6 +87,6 @@ hazmat = []
 legacy_compatibility = ["curve25519-dalek/legacy_compatibility"]
 pkcs8 = ["ed25519/pkcs8"]
 pem = ["alloc", "ed25519/pem", "pkcs8"]
-rand_core = ["dep:rand_core"]
+rand_core = ["dep:rand_core", "curve25519-dalek/rand_core", "signature/rand_core"]
 serde = ["dep:serde", "ed25519/serde"]
 zeroize = ["dep:zeroize", "curve25519-dalek/zeroize"]

ed25519-dalek/README.md

@@ -22,7 +22,7 @@ This crate is `#[no_std]` compatible with `default-features = false`.
 | `zeroize`              | ✓        | Implements `Zeroize` and `ZeroizeOnDrop` for `SigningKey` |
 | `rand_core`            |          | Enables `SigningKey::generate` |
 | `batch`                |          | Enables `verify_batch` for verifying many signatures quickly. Also enables `alloc` and `rand_core`. |
-| `digest`               |          | Enables `Context`, `SigningKey::{with_context, sign_prehashed}` and `VerifyingKey::{with_context, verify_prehashed, verify_prehashed_strict}` for Ed25519ph prehashed signatures |
+| `digest`               |          | Enables `Context`, `SigningKey::{with_context, sign_prehashed}` and `VerifyingKey::{with_context, verify_prehashed, verify_prehashed_strict}` for Ed25519ph prehashed signatures. Implements `KeySizeUser` for `VerifyingKey`, and `KeySizeUser + TryKeyInit + Generate` for `SigningKey`.
 | `pkcs8`                |          | Enables [PKCS#8](https://en.wikipedia.org/wiki/PKCS_8) serialization/deserialization for `SigningKey` and `VerifyingKey` |
 | `pem`                  |          | Enables PEM serialization support for PKCS#8 private keys and SPKI public keys. Also enables `alloc`. |
 | `legacy_compatibility` |          | **Unsafe:** Disables certain signature checks. See [below](#malleability-and-the-legacy_compatibility-feature) |

ed25519-dalek/src/signing.rs

@@ -20,6 +20,15 @@ use rand_core::CryptoRng;
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Deserializer, Serialize, Serializer};
 
+#[cfg(feature = "digest")]
+use curve25519_dalek::digest::{
+    common::{InvalidKey, Key, KeySizeUser, TryKeyInit},
+    typenum::U32,
+};
+
+#[cfg(all(feature = "digest", feature = "rand_core"))]
+use curve25519_dalek::digest::common::Generate;
+
 use sha2::Sha512;
 use subtle::{Choice, ConstantTimeEq};
 
@@ -545,6 +554,29 @@ impl SigningKey {
     }
 }
 
+#[cfg(feature = "digest")]
+impl KeySizeUser for SigningKey {
+    type KeySize = U32;
+}
+
+#[cfg(feature = "digest")]
+impl TryKeyInit for SigningKey {
+    fn new(key: &Key<Self>) -> Result<Self, InvalidKey> {
+        Ok(Self::from_bytes(key.as_ref()))
+    }
+}
+
+#[cfg(all(feature = "digest", feature = "rand_core"))]
+impl Generate for SigningKey {
+    fn try_generate_from_rng<R: rand_core::TryCryptoRng + ?Sized>(
+        rng: &mut R,
+    ) -> Result<Self, R::Error> {
+        let mut secret = SecretKey::default();
+        rng.try_fill_bytes(&mut secret)?;
+        Ok(Self::from_bytes(&secret))
+    }
+}
+
 impl AsRef<VerifyingKey> for SigningKey {
     fn as_ref(&self) -> &VerifyingKey {
         &self.verifying_key

ed25519-dalek/src/verifying.rs

@@ -9,6 +9,9 @@
 
 //! ed25519 public keys.
 
+#[cfg(feature = "digest")]
+use curve25519_dalek::digest::{common::KeySizeUser, typenum::U32};
+
 use core::fmt::Debug;
 use core::hash::{Hash, Hasher};
 
@@ -116,6 +119,11 @@ impl From<EdwardsPoint> for VerifyingKey {
     }
 }
 
+#[cfg(feature = "digest")]
+impl KeySizeUser for VerifyingKey {
+    type KeySize = U32;
+}
+
 impl VerifyingKey {
     /// Convert this public key to a byte array.
     #[inline]