lms,ml-dsa: relax Sized requirement on the rng (#918)

Author: baloo

lms/src/lms/private.rs

@@ -7,7 +7,6 @@ use crate::types::{Identifier, Typecode};
 
 use digest::{Digest, Output, OutputSizeUser};
 use hybrid_array::{Array, ArraySize};
-use rand::Rng;
 use rand_core::{CryptoRng, TryCryptoRng};
 use signature::{Error, RandomizedSignerMut};
 
@@ -32,7 +31,7 @@ pub struct SigningKey<Mode: LmsMode> {
 impl<Mode: LmsMode> SigningKey<Mode> {
     /// Creates a new private key with a random identifier using
     /// algorithm 5 from <https://datatracker.ietf.org/doc/html/rfc8554#section-5.2>
-    pub fn new(mut rng: impl Rng + CryptoRng) -> Self {
+    pub fn new<R: CryptoRng + ?Sized>(rng: &mut R) -> Self {
         let mut id = Identifier::default();
         rng.fill_bytes(id.as_mut());
 

lms/src/lms/public.rs

@@ -258,8 +258,8 @@ mod tests {
         <Mode::Hasher as OutputSizeUser>::OutputSize: Add<U24>,
         Sum<<Mode::Hasher as OutputSizeUser>::OutputSize, U24>: ArraySize,
     {
-        let rng = rand::rng();
-        let lms_priv = SigningKey::<Mode>::new(rng);
+        let mut rng = rand::rng();
+        let lms_priv = SigningKey::<Mode>::new(&mut rng);
         let lms_pub = lms_priv.public();
         let lms_pub_serialized: Array<u8, Sum<<Mode::Hasher as OutputSizeUser>::OutputSize, U24>> =
             lms_pub.clone().into();

ml-dsa/benches/ml_dsa.rs

@@ -1,9 +1,9 @@
 use criterion::{Criterion, criterion_group, criterion_main};
 use hybrid_array::{Array, ArraySize};
 use ml_dsa::{B32, KeyGen, MlDsa65, Signature, SigningKey, VerifyingKey};
-use rand::{CryptoRng, RngCore};
+use rand::CryptoRng;
 
-pub fn rand<L: ArraySize>(rng: &mut (impl RngCore + CryptoRng)) -> Array<u8, L> {
+pub fn rand<L: ArraySize, R: CryptoRng + ?Sized>(rng: &mut R) -> Array<u8, L> {
     let mut val = Array::<u8, L>::default();
     rng.fill_bytes(&mut val);
     val

ml-dsa/src/lib.rs

@@ -780,7 +780,7 @@ pub trait KeyGen: MlDsaParams {
 
     /// Generate a signing key pair from the specified RNG
     #[cfg(feature = "rand_core")]
-    fn key_gen<R: CryptoRng>(rng: &mut R) -> Self::KeyPair;
+    fn key_gen<R: CryptoRng + ?Sized>(rng: &mut R) -> Self::KeyPair;
 
     /// Deterministically generate a signing key pair from the specified seed
     // TODO(RLB): Only expose this based on a feature.
@@ -796,7 +796,7 @@ where
     /// Generate a signing key pair from the specified RNG
     // Algorithm 1 ML-DSA.KeyGen()
     #[cfg(feature = "rand_core")]
-    fn key_gen<R: CryptoRng>(rng: &mut R) -> KeyPair<P> {
+    fn key_gen<R: CryptoRng + ?Sized>(rng: &mut R) -> KeyPair<P> {
         let mut xi = B32::default();
         rng.fill_bytes(&mut xi);
         Self::key_gen_internal(&xi)