Update curve25519-dalek (#94)

Cargo.toml

@@ -21,8 +21,9 @@ serde = ["generic-array/serde", "serde_"]
 std = ["alloc"]
 
 [dependencies]
-curve25519-dalek = { version = "=4.0.0-pre.5", default-features = false, features = [
+curve25519-dalek = { version = "=4.0.0-rc.0", default-features = false, features = [
   "rand_core",
+  "zeroize",
 ], optional = true }
 derive-where = { version = "1", features = ["zeroize-on-drop"] }
 digest = "0.10"

src/group/ristretto.rs

@@ -86,11 +86,8 @@ impl Group for Ristretto255 {
     }
 
     fn deserialize_elem(element_bits: &[u8]) -> Result<Self::Elem> {
-        if element_bits.len() != 32 {
-            return Err(Error::Deserialization);
-        }
-
         CompressedRistretto::from_slice(element_bits)
+            .map_err(|_| Error::Deserialization)?
             .decompress()
             .filter(|point| point != &RistrettoPoint::identity())
             .ok_or(Error::Deserialization)