1 files changed, 38 insertions, 0 deletions
diff --git a/vendor/crypto-bigint/src/limb/rand.rs b/vendor/crypto-bigint/src/limb/rand.rs
new file mode 100644
index 0000000..4347168
--- /dev/null
+++ b/vendor/crypto-bigint/src/limb/rand.rs
@@ -0,0 +1,38 @@
+//! Random number generator support
+
+use super::Limb;
+use crate::{Encoding, NonZero, Random, RandomMod};
+use rand_core::CryptoRngCore;
+use subtle::ConstantTimeLess;
+
+impl Random for Limb {
+    #[cfg(target_pointer_width = "32")]
+    fn random(rng: &mut impl CryptoRngCore) -> Self {
+        Self(rng.next_u32())
+    }
+
+    #[cfg(target_pointer_width = "64")]
+    fn random(rng: &mut impl CryptoRngCore) -> Self {
+        Self(rng.next_u64())
+    }
+}
+
+impl RandomMod for Limb {
+    fn random_mod(rng: &mut impl CryptoRngCore, modulus: &NonZero<Self>) -> Self {
+        let mut bytes = <Self as Encoding>::Repr::default();
+
+        let n_bits = modulus.bits();
+        let n_bytes = (n_bits + 7) / 8;
+        let mask = 0xff >> (8 * n_bytes - n_bits);
+
+        loop {
+            rng.fill_bytes(&mut bytes[..n_bytes]);
+            bytes[n_bytes - 1] &= mask;
+
+            let n = Limb::from_le_bytes(bytes);
+            if n.ct_lt(modulus).into() {
+                return n;
+            }
+        }
+    }
+}