1 files changed, 47 insertions, 0 deletions
diff --git a/vendor/crypto-bigint/src/boxed/uint/cmp.rs b/vendor/crypto-bigint/src/boxed/uint/cmp.rs
new file mode 100644
index 000000000..d850fc7d4
--- /dev/null
+++ b/vendor/crypto-bigint/src/boxed/uint/cmp.rs
@@ -0,0 +1,47 @@
+//! [`BoxedUint`] comparisons.
+//!
+//! By default these are all constant-time and use the `subtle` crate.
+
+use super::BoxedUint;
+use crate::Limb;
+use subtle::{Choice, ConstantTimeEq};
+
+impl ConstantTimeEq for BoxedUint {
+    #[inline]
+    fn ct_eq(&self, other: &Self) -> Choice {
+        let (shorter, longer) = Self::sort_by_precision(self, other);
+        let mut ret = Choice::from(1u8);
+
+        for i in 0..longer.limbs.len() {
+            let a = shorter.limbs.get(i).unwrap_or(&Limb::ZERO);
+            let b = longer.limbs.get(i).unwrap_or(&Limb::ZERO);
+            ret &= a.ct_eq(b);
+        }
+
+        ret
+    }
+}
+
+impl Eq for BoxedUint {}
+impl PartialEq for BoxedUint {
+    fn eq(&self, other: &Self) -> bool {
+        self.ct_eq(other).into()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::BoxedUint;
+    use subtle::ConstantTimeEq;
+
+    #[test]
+    fn ct_eq() {
+        let a = BoxedUint::zero();
+        let b = BoxedUint::one();
+
+        assert!(bool::from(a.ct_eq(&a)));
+        assert!(!bool::from(a.ct_eq(&b)));
+        assert!(!bool::from(b.ct_eq(&a)));
+        assert!(bool::from(b.ct_eq(&b)));
+    }
+}