Added Drop to SharedSecret and SecretKey

src/lib.rs

@@ -368,7 +368,13 @@ impl Default for SecretKey {
 
 impl Into<Scalar> for SecretKey {
     fn into(self) -> Scalar {
-        self.0
+        self.0.clone()
+    }
+}
+
+impl Drop for SecretKey {
+    fn drop(&mut self) {
+        self.0.clear();
     }
 }
 
@@ -573,6 +579,7 @@ impl SharedSecret {
 
         Ok(SharedSecret(inner))
     }
+
 }
 
 impl AsRef<[u8]> for SharedSecret {
@@ -581,6 +588,14 @@ impl AsRef<[u8]> for SharedSecret {
     }
 }
 
+impl Drop for SharedSecret {
+    fn drop(&mut self) {
+         unsafe {
+            core::ptr::write_volatile(&mut self.0, [0u8; 32]);
+        }
+    }
+}
+
 /// Check signature is a valid message signed by public key.
 pub fn verify(message: &Message, signature: &Signature, pubkey: &PublicKey) -> bool {
     ECMULT_CONTEXT.verify_raw(&signature.r, &signature.s, &pubkey.0, &message.0)

src/scalar.rs

@@ -31,7 +31,9 @@ pub struct Scalar(pub [u32; 8]);
 impl Scalar {
     /// Clear a scalar to prevent the leak of sensitive data.
     pub fn clear(&mut self) {
-        self.0 = [0u32; 8];
+        unsafe {
+            core::ptr::write_volatile(&mut self.0, [0u32; 8]);
+        }
     }
 
     /// Set a scalar to an unsigned integer.