Make BLS Point nominal to avoid incorrect Coercible instances

IntersectMBO · Mar 23, 2023 · c41c920 · c41c920
1 parent 18a0d00
commit c41c920
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/cardano-crypto-class/src/Cardano/Crypto/EllipticCurve/BLS12_381/Internal.hs b/cardano-crypto-class/src/Cardano/Crypto/EllipticCurve/BLS12_381/Internal.hs
@@ -5,6 +5,7 @@
 {-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE BangPatterns #-}
+{-# LANGUAGE RoleAnnotations #-}
 
 module Cardano.Crypto.EllipticCurve.BLS12_381.Internal
 (
@@ -221,6 +222,10 @@ instance BLS curve => Eq (AffinePtr curve) where
 -- | prime order subgroup.
 newtype Point curve = Point (ForeignPtr Void)
 
+-- Making sure different 'Point's are not 'Coercible', which would ruin the
+-- intended type safety:
+type role Point nominal
+
 type Point1 = Point Curve1
 type Point2 = Point Curve2