Make rand_core optional (#262)

* Make rand_core optional
* Bench requires features rand_core

.github/workflows/rust.yml

@@ -30,6 +30,7 @@ jobs:
       - run: cargo test --target ${{ matrix.target }} --no-default-features --features alloc --lib
       - run: cargo test --target ${{ matrix.target }}
       - run: cargo test --target ${{ matrix.target }} --features batch
+      - run: cargo test --target ${{ matrix.target }} --features rand_core
       - run: cargo test --target ${{ matrix.target }} --features serde
       - run: cargo test --target ${{ matrix.target }} --features pem
 

Cargo.toml

@@ -34,6 +34,7 @@ sha2 = { version = "0.10", default-features = false }
 zeroize = { version = "1.5", default-features = false, optional = true }
 
 [dev-dependencies]
+curve25519-dalek = { version = "=4.0.0-pre.5", default-features = false, features = ["digest", "rand_core"] }
 hex = "0.4"
 bincode = "1.0"
 serde_json = "1.0"
@@ -43,14 +44,14 @@ rand = "0.8"
 rand_core = { version = "0.6.4", default-features = false }
 serde = { version = "1.0", features = ["derive"] }
 toml = { version = "0.5" }
-curve25519-dalek = { version = "=4.0.0-pre.5", default-features = false, features = ["digest", "rand_core"] }
 
 [[bench]]
 name = "ed25519_benchmarks"
 harness = false
+required-features = ["rand_core"]
 
 [features]
-default = ["std", "rand_core", "zeroize"]
+default = ["std", "zeroize"]
 alloc = ["curve25519-dalek/alloc", "ed25519/alloc", "serde?/alloc", "zeroize/alloc"]
 std = ["alloc", "ed25519/std", "serde?/std", "sha2/std"]
 
@@ -60,6 +61,7 @@ batch = ["alloc", "merlin", "rand_core"]
 legacy_compatibility = []
 pkcs8 = ["ed25519/pkcs8"]
 pem = ["alloc", "ed25519/pem", "pkcs8"]
+rand_core = ["dep:rand_core"]
 serde = ["dep:serde", "serde_bytes", "ed25519/serde"]
 zeroize = ["dep:zeroize", "curve25519-dalek/zeroize"]
 

src/signing.rs

@@ -12,7 +12,7 @@
 #[cfg(feature = "pkcs8")]
 use ed25519::pkcs8::{self, DecodePrivateKey};
 
-#[cfg(feature = "rand_core")]
+#[cfg(any(test, feature = "rand_core"))]
 use rand_core::CryptoRngCore;
 
 #[cfg(feature = "serde")]
@@ -183,7 +183,7 @@ impl SigningKey {
     /// The standard hash function used for most ed25519 libraries is SHA-512,
     /// which is available with `use sha2::Sha512` as in the example above.
     /// Other suitable hash functions include Keccak-512 and Blake2b-512.
-    #[cfg(feature = "rand_core")]
+    #[cfg(any(test, feature = "rand_core"))]
     pub fn generate<R: CryptoRngCore + ?Sized>(csprng: &mut R) -> SigningKey {
         let mut secret = SecretKey::default();
         csprng.fill_bytes(&mut secret);
@@ -208,7 +208,8 @@ impl SigningKey {
     ///
     /// # Examples
     ///
-    /// ```
+    #[cfg_attr(feature = "rand_core", doc = "```")]
+    #[cfg_attr(not(feature = "rand_core"), doc = "```ignore")]
     /// use ed25519_dalek::Digest;
     /// use ed25519_dalek::SigningKey;
     /// use ed25519_dalek::Sha512;

tests/ed25519.rs

@@ -16,9 +16,6 @@ use ed25519_dalek::*;
 use hex::FromHex;
 use hex_literal::hex;
 
-#[cfg(feature = "rand_core")]
-use sha2::Sha512;
-
 #[cfg(test)]
 mod vectors {
     use super::*;
@@ -285,6 +282,7 @@ mod vectors {
 mod integrations {
     use super::*;
     use rand::rngs::OsRng;
+    use sha2::Sha512;
 
     #[test]
     fn sign_verify() {