Add BlockRngCore trait

Author: pitdicker

src/lib.rs

@@ -1002,6 +1002,15 @@ impl<R: SeedableRng> NewRng for R {
     }
 }
 
+/// Trait for RNG's that do not generate random numbers one at a time, but in
+/// blocks. Especially for cryptographic RNG's it is common to generate 16 or
+/// more results at a time.
+pub trait BlockRngCore<T>: Sized {
+    type Results: AsRef<[T]> + Default;
+
+    fn generate(&mut self, results: &mut Self::Results) -> Result<(), Error>;
+}
+
 /// The standard RNG. The PRNG algorithm in `StdRng` is choosen to be efficient
 /// on the current platform, to be statistically strong and unpredictable
 /// (meaning a cryptographically secure PRNG).