Move to ZeroizeOnDrop (#54)

* Move from `Zeroize` to `ZeroizeOnDrop`

* Pin pre-release dependencies

Author: daxpedda

Cargo.toml

@@ -27,10 +27,10 @@ std = ["alloc"]
 
 [dependencies]
 curve25519-dalek = { version = "3", default-features = false, optional = true }
-derive-where = { version = "1.0.0-rc.1", features = ["zeroize"] }
+derive-where = { version = "=1.0.0-rc.2", features = ["zeroize-on-drop"] }
 digest = "0.10"
 displaydoc = { version = "0.2", default-features = false }
-elliptic-curve = { version = "0.12.0-pre.1", features = [
+elliptic-curve = { version = "=0.12.0-pre.1", features = [
   "hash2curve",
   "sec1",
   "voprf",
@@ -42,13 +42,13 @@ serde_ = { version = "1", package = "serde", default-features = false, features
 ], optional = true }
 sha2 = { version = "0.10", default-features = false, optional = true }
 subtle = { version = "2.3", default-features = false }
-zeroize = { version = "1", default-features = false }
+zeroize = { version = "1.5", default-features = false }
 
 [dev-dependencies]
 generic-array = { version = "0.14", features = ["more_lengths"] }
 hex = "0.4"
 json = "0.12"
-p256 = { version = "0.11.0-pre.0", default-features = false, features = [
+p256 = { version = "=0.11.0-pre.0", default-features = false, features = [
   "hash2curve",
   "voprf",
 ] }

src/lib.rs

@@ -476,7 +476,7 @@
 //!
 //! [curve25519-dalek]: (https://doc.dalek.rs/curve25519_dalek/index.html#backends-and-features)
 
-#![deny(unsafe_code)]
+#![cfg_attr(not(test), deny(unsafe_code))]
 #![no_std]
 #![warn(
     clippy::cargo,

src/voprf.rs

@@ -11,7 +11,7 @@
 use alloc::vec::Vec;
 use core::iter::{self, Map, Repeat, Zip};
 
-use derive_where::DeriveWhere;
+use derive_where::derive_where;
 use digest::core_api::BlockSizeUser;
 use digest::{Digest, Output, OutputSizeUser};
 use generic_array::sequence::Concat;
@@ -64,8 +64,7 @@ impl Mode {
 
 /// A client which engages with a [NonVerifiableServer] in base mode, meaning
 /// that the OPRF outputs are not verifiable.
-#[derive(DeriveWhere)]
-#[derive_where(Clone, Zeroize(drop))]
+#[derive_where(Clone, ZeroizeOnDrop)]
 #[derive_where(Debug, Eq, Hash, Ord, PartialEq, PartialOrd; <CS::Group as Group>::Scalar)]
 #[cfg_attr(
     feature = "serde",
@@ -83,8 +82,7 @@ where
 
 /// A client which engages with a [VerifiableServer] in verifiable mode, meaning
 /// that the OPRF outputs can be checked against a server public key.
-#[derive(DeriveWhere)]
-#[derive_where(Clone, Zeroize(drop))]
+#[derive_where(Clone, ZeroizeOnDrop)]
 #[derive_where(Debug, Eq, Hash, Ord, PartialEq, PartialOrd; <CS::Group as Group>::Scalar, <CS::Group as Group>::Elem)]
 #[cfg_attr(
     feature = "serde",
@@ -104,8 +102,7 @@ where
 
 /// A server which engages with a [NonVerifiableClient] in base mode, meaning
 /// that the OPRF outputs are not verifiable.
-#[derive(DeriveWhere)]
-#[derive_where(Clone, Zeroize(drop))]
+#[derive_where(Clone, ZeroizeOnDrop)]
 #[derive_where(Debug, Eq, Hash, Ord, PartialEq, PartialOrd; <CS::Group as Group>::Scalar)]
 #[cfg_attr(
     feature = "serde",
@@ -123,8 +120,7 @@ where
 
 /// A server which engages with a [VerifiableClient] in verifiable mode, meaning
 /// that the OPRF outputs can be checked against a server public key.
-#[derive(DeriveWhere)]
-#[derive_where(Clone, Zeroize(drop))]
+#[derive_where(Clone, ZeroizeOnDrop)]
 #[derive_where(Debug, Eq, Hash, Ord, PartialEq, PartialOrd; <CS::Group as Group>::Scalar, <CS::Group as Group>::Elem)]
 #[cfg_attr(
     feature = "serde",
@@ -144,8 +140,7 @@ where
 
 /// A proof produced by a [VerifiableServer] that the OPRF output matches
 /// against a server public key.
-#[derive(DeriveWhere)]
-#[derive_where(Clone, Zeroize(drop))]
+#[derive_where(Clone, ZeroizeOnDrop)]
 #[derive_where(Debug, Eq, Hash, Ord, PartialEq, PartialOrd; <CS::Group as Group>::Scalar)]
 #[cfg_attr(
     feature = "serde",
@@ -165,8 +160,7 @@ where
 
 /// The first client message sent from a client (either verifiable or not) to a
 /// server (either verifiable or not).
-#[derive(DeriveWhere)]
-#[derive_where(Clone, Zeroize(drop))]
+#[derive_where(Clone, ZeroizeOnDrop)]
 #[derive_where(Debug, Eq, Hash, Ord, PartialEq, PartialOrd; <CS::Group as Group>::Elem)]
 #[cfg_attr(
     feature = "serde",
@@ -183,8 +177,7 @@ where
 
 /// The server's response to the [BlindedElement] message from a client (either
 /// verifiable or not) to a server (either verifiable or not).
-#[derive(DeriveWhere)]
-#[derive_where(Clone, Zeroize(drop))]
+#[derive_where(Clone, ZeroizeOnDrop)]
 #[derive_where(Debug, Eq, Hash, Ord, PartialEq, PartialOrd; <CS::Group as Group>::Elem)]
 #[cfg_attr(
     feature = "serde",
@@ -768,7 +761,6 @@ where
 /////////////////////////
 
 /// Contains the fields that are returned by a non-verifiable client blind
-#[derive(DeriveWhere)]
 #[derive_where(Debug; <CS::Group as Group>::Scalar, <CS::Group as Group>::Elem)]
 pub struct NonVerifiableClientBlindResult<CS: CipherSuite>
 where
@@ -782,7 +774,6 @@ where
 }
 
 /// Contains the fields that are returned by a verifiable client blind
-#[derive(DeriveWhere)]
 #[derive_where(Debug; <CS::Group as Group>::Scalar, <CS::Group as Group>::Elem)]
 pub struct VerifiableClientBlindResult<CS: CipherSuite>
 where
@@ -804,7 +795,6 @@ pub type VerifiableClientBatchFinalizeResult<'a, C, I, II, IC, IM> = FinalizeAft
 >;
 
 /// Contains the fields that are returned by a verifiable server evaluate
-#[derive(DeriveWhere)]
 #[derive_where(Debug; <CS::Group as Group>::Scalar, <CS::Group as Group>::Elem)]
 pub struct VerifiableServerEvaluateResult<CS: CipherSuite>
 where
@@ -819,8 +809,7 @@ where
 
 /// Contains prepared [`EvaluationElement`]s by a verifiable server batch
 /// evaluate preparation.
-#[derive(DeriveWhere)]
-#[derive_where(Clone, Zeroize(drop))]
+#[derive_where(Clone, ZeroizeOnDrop)]
 #[derive_where(Debug, Eq, Hash, Ord, PartialEq, PartialOrd; <CS::Group as Group>::Elem)]
 #[cfg_attr(
     feature = "serde",
@@ -833,8 +822,7 @@ where
         IsLess<U256> + IsLessOrEqual<<CS::Hash as BlockSizeUser>::BlockSize>;
 
 /// Contains the prepared `t` by a verifiable server batch evaluate preparation.
-#[derive(DeriveWhere)]
-#[derive_where(Clone, Zeroize(drop))]
+#[derive_where(Clone, ZeroizeOnDrop)]
 #[derive_where(Debug, Eq, Hash, Ord, PartialEq, PartialOrd; <CS::Group as Group>::Scalar)]
 #[cfg_attr(
     feature = "serde",
@@ -863,7 +851,6 @@ pub type VerifiableServerBatchEvaluatePreparedEvaluationElements<CS, I> = Map<
 
 /// Contains the fields that are returned by a verifiable server batch evaluate
 /// preparation.
-#[derive(DeriveWhere)]
 #[derive_where(Debug; I, <CS::Group as Group>::Scalar)]
 pub struct VerifiableServerBatchEvaluatePrepareResult<
     'a,
@@ -889,7 +876,6 @@ pub type VerifiableServerBatchEvaluateFinishedMessages<'a, CS, I> = Map<
 
 /// Contains the fields that are returned by a verifiable server batch evaluate
 /// finish.
-#[derive(DeriveWhere)]
 #[derive_where(Debug; <&'a I as core::iter::IntoIterator>::IntoIter, <CS::Group as Group>::Scalar)]
 pub struct VerifiableServerBatchEvaluateFinishResult<'a, CS: 'a + CipherSuite, I>
 where
@@ -904,7 +890,6 @@ where
 }
 
 /// Contains the fields that are returned by a verifiable server batch evaluate
-#[derive(DeriveWhere)]
 #[derive_where(Debug; <CS::Group as Group>::Scalar, <CS::Group as Group>::Elem)]
 #[cfg(feature = "alloc")]
 pub struct VerifiableServerBatchEvaluateResult<CS: CipherSuite>
@@ -1319,13 +1304,13 @@ where
 #[cfg(test)]
 mod tests {
     use core::ops::Add;
+    use core::ptr;
 
     use ::alloc::vec;
     use ::alloc::vec::Vec;
     use generic_array::typenum::Sum;
     use generic_array::ArrayLength;
     use rand::rngs::OsRng;
-    use zeroize::Zeroize;
 
     use super::*;
     use crate::Group;
@@ -1579,11 +1564,11 @@ mod tests {
         let client_blind_result = NonVerifiableClient::<CS>::blind(input, &mut rng).unwrap();
 
         let mut state = client_blind_result.state;
-        Zeroize::zeroize(&mut state);
+        unsafe { ptr::drop_in_place(&mut state) };
         assert!(state.serialize().iter().all(|&x| x == 0));
 
         let mut message = client_blind_result.message;
-        Zeroize::zeroize(&mut message);
+        unsafe { ptr::drop_in_place(&mut message) };
         assert!(message.serialize().iter().all(|&x| x == 0));
     }
 
@@ -1599,11 +1584,11 @@ mod tests {
         let client_blind_result = VerifiableClient::<CS>::blind(input, &mut rng).unwrap();
 
         let mut state = client_blind_result.state;
-        Zeroize::zeroize(&mut state);
+        unsafe { ptr::drop_in_place(&mut state) };
         assert!(state.serialize().iter().all(|&x| x == 0));
 
         let mut message = client_blind_result.message;
-        Zeroize::zeroize(&mut message);
+        unsafe { ptr::drop_in_place(&mut message) };
         assert!(message.serialize().iter().all(|&x| x == 0));
     }
 
@@ -1617,16 +1602,15 @@ mod tests {
         let mut rng = OsRng;
         let client_blind_result = NonVerifiableClient::<CS>::blind(input, &mut rng).unwrap();
         let server = NonVerifiableServer::<CS>::new(&mut rng);
-        let message = server
+        let mut message = server
             .evaluate(&client_blind_result.message, Some(info))
             .unwrap();
 
         let mut state = server;
-        Zeroize::zeroize(&mut state);
+        unsafe { ptr::drop_in_place(&mut state) };
         assert!(state.serialize().iter().all(|&x| x == 0));
 
-        let mut message = message;
-        Zeroize::zeroize(&mut message);
+        unsafe { ptr::drop_in_place(&mut message) };
         assert!(message.serialize().iter().all(|&x| x == 0));
     }
 
@@ -1649,15 +1633,15 @@ mod tests {
             .unwrap();
 
         let mut state = server;
-        Zeroize::zeroize(&mut state);
+        unsafe { ptr::drop_in_place(&mut state) };
         assert!(state.serialize().iter().all(|&x| x == 0));
 
         let mut message = server_result.message;
-        Zeroize::zeroize(&mut message);
+        unsafe { ptr::drop_in_place(&mut message) };
         assert!(message.serialize().iter().all(|&x| x == 0));
 
         let mut proof = server_result.proof;
-        Zeroize::zeroize(&mut proof);
+        unsafe { ptr::drop_in_place(&mut proof) };
         assert!(proof.serialize().iter().all(|&x| x == 0));
     }