Merge a7b121eccc into d275613c37

curve25519/solana-ed25519/src/edwards.rs

@@ -121,6 +121,7 @@ use {
 use rand_core::{CryptoRng, RngCore};
 
 use subtle::Choice;
+use subtle::ConditionallyNegatable;
 use subtle::ConditionallySelectable;
 use subtle::ConstantTimeEq;
 
@@ -245,13 +246,7 @@ mod decompress {
          // FieldElement::sqrt_ratio_i always returns the nonnegative square root,
          // so we negate according to the supplied sign bit.
         let compressed_sign_bit = Choice::from(repr.as_bytes()[31] >> 7);
-        // AENEAS-COMPAT: negate-then-conditional-assign instead of
-        // `X.conditional_negate(...)` — semantically identical and still
-        // constant-time, but avoids subtle's `ConditionallyNegatable`
-        // blanket impl which breaks the verification toolchain (the same
-        // documented rewrite as in `FieldElement::sqrt_ratio_i`).
-        let X_neg = -&X;
-        X.conditional_assign(&X_neg, compressed_sign_bit);
+        X.conditional_negate(compressed_sign_bit);
 
         EdwardsPoint {
             X,