Use ct_gt instead of gt

Author: xuganyu96

src/uint/boxed/cmp.rs

@@ -11,13 +11,6 @@ use subtle::{
 };
 
 impl BoxedUint {
-    /// Returns the truthy value if `self >= rhs` and the falsy value otherwise.
-    #[inline]
-    pub(crate) fn gt(lhs: &Self, rhs: &Self) -> ConstChoice {
-        let (_res, borrow) = rhs.sbb(lhs, Limb::ZERO);
-        ConstChoice::from_word_mask(borrow.0)
-    }
-
     /// Returns the Ordering between `self` and `rhs` in variable time.
     pub fn cmp_vartime(&self, rhs: &Self) -> Ordering {
         debug_assert_eq!(self.limbs.len(), rhs.limbs.len());

src/uint/boxed/sqrt.rs

@@ -1,6 +1,6 @@
 //! [`BoxedUint`] square root operations.
 
-use subtle::{ConstantTimeEq, CtOption};
+use subtle::{ConstantTimeEq, ConstantTimeGreater, CtOption};
 
 use crate::{BoxedUint, NonZero};
 
@@ -48,7 +48,7 @@ impl BoxedUint {
         // At this point `x_prev == x_{n}` and `x == x_{n+1}`
         // where `n == i - 1 == LOG2_BITS + 1 == floor(log2(BITS)) + 1`.
         // Thus, according to Hast, `sqrt(self) = min(x_n, x_{n+1})`.
-        Self::conditional_select(&x_prev, &x, Self::gt(&x_prev, &x).into())
+        Self::conditional_select(&x_prev, &x, Self::ct_gt(&x_prev, &x))
     }
 
     /// Computes √(`self`)