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Specify the RNG for Scalar::random.

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Isis Lovecruft 2016-12-14 05:38:06 +00:00
parent a339da82e7
commit c9b0e45afb
Failed to extract signature
1 changed files with 16 additions and 7 deletions
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23
src/scalar.rs
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@ -29,7 +29,6 @@
use std::clone::Clone;
use std::ops::{Index, IndexMut};
use rand::OsRng;
use rand::Rng;
use field::{load3, load4};
@ -65,12 +64,18 @@ impl IndexMut<usize> for Scalar {
impl Scalar {
/// Return a `Scalar` chosen uniformly at random using a CSPRNG.
/// Panics if the operating system's CSPRNG is unavailable.
pub fn random() -> Self {
// XXX is there a more efficient way than building
// the rng every time here?
let mut rng = OsRng::new().unwrap();
///
/// # Inputs
///
/// * `cspring`: any cryptographically secure PRNG which
/// implements the `rand::Rng` interface.
///
/// # Returns
///
/// A random scalar within ℤ/lℤ.
pub fn random<T: Rng>(csprng: &mut T) -> Self {
let mut scalar_bytes = [0u8; 64];
rng.fill_bytes(&mut scalar_bytes);
csprng.fill_bytes(&mut scalar_bytes);
Scalar::reduce(&scalar_bytes)
}
@ -428,12 +433,16 @@ impl Scalar {
#[cfg(test)]
mod test {
use rand::Rng;
use rand::OsRng;
use super::*;
use test::Bencher;
#[bench]
fn bench_scalar_random(b: &mut Bencher) {
b.iter(|| Scalar::random());
let mut csprng: OsRng = OsRng::new().unwrap();
b.iter(|| Scalar::random(&mut csprng));
}
#[bench]