Clean up and add parity codec support (#91)

* clean Cargo.toml and add parity codec support

* upgrade parity codec

* fix travis

* make clippy happy

* use zeroize instead of memsec

* fix zeroize and add test

* Update .travis.yml

* improve codec support

* fix

* add TODO for removing clear_fr

.travis.yml

@@ -1,6 +1,6 @@
 language: rust
 rust:
-    - 1.35.0
+  - 1.39.0
 cache:
   cargo: true
   timeout: 1200

Cargo.toml

@@ -19,22 +19,23 @@ description = "Pairing threshold cryptography"
 edition = "2018"
 
 [dependencies]
-byteorder = "1.2.7"
-errno = "0.2.4"
-failure = "0.1.5"
+byteorder = "1.3.2"
+failure = "0.1.6"
 hex_fmt = "0.3.0"
-log = "0.4.6"
-memsec = "0.5.4"
+log = "0.4.8"
 pairing = { version = "0.14.2", features = ["u128-support"] }
 rand = "0.6.5"
 rand04_compat = "0.1.1"
 rand_chacha = "0.1.1"
-serde = { version = "1.0.89", features = ["derive"] }
-tiny-keccak = "1.4.2"
+serde = { version = "1.0.102", features = ["derive"] }
+tiny-keccak = "1.5.0"
+codec = { package = "parity-scale-codec", version = "1.0.6", default-features = false, features = ["derive"], optional = true  }
+bincode = { version = "1.2", optional = true }
+zeroize = "1.0"
 
 [dev-dependencies]
-bincode = "1.0.1"
-criterion = "0.2.7"
+bincode = "1.2"
+criterion = "0.3.0"
 rand_xorshift = "0.1.1"
 
 [[bench]]
@@ -43,3 +44,4 @@ harness = false
 
 [features]
 use-insecure-test-only-mock-crypto = []
+codec-support = ["codec", "bincode"]

examples/threshold_enc.rs

@@ -147,7 +147,7 @@ fn main() {
     let ciphertext = pk.encrypt(msg);
     send_msg(society.get_actor(alice), ciphertext.clone());
     send_msg(society.get_actor(bob), ciphertext.clone());
-    send_msg(society.get_actor(clara), ciphertext.clone());
+    send_msg(society.get_actor(clara), ciphertext);
 
     // We start a meeting of the secret society. At the meeting, each actor contributes their
     // share of the decryption process to decrypt the ciphertext that they each received.

examples/threshold_sig.rs

@@ -216,7 +216,7 @@ fn main() {
     // message now has two signatures (which is `threshold + 1` signatures). The network runs a
     // round of consensus, which successfully creates a combined-signature for Alice's message.
     // Alice's message is appended to the chat log.
-    alice.send(network.get_mut_node(node2), alice_greeting.clone());
+    alice.send(network.get_mut_node(node2), alice_greeting);
     network.step();
     assert_eq!(network.chat_log.len(), 1);
 }

src/codec_impl.rs

@@ -0,0 +1,27 @@
+#[macro_export]
+/// implement parity codec for type
+macro_rules! impl_codec_for {
+    ($type:ty) => {
+        impl codec::Encode for $type {
+            fn encode(&self) -> Vec<u8> {
+                let encoded = bincode::serialize(&self).unwrap();
+                codec::Encode::encode(&encoded)
+            }
+        }
+
+        impl codec::Decode for $type {
+            fn decode<I: codec::Input>(value: &mut I) -> std::result::Result<Self, codec::Error> {
+                let decoded: Vec<u8> = codec::Decode::decode(value)?;
+                bincode::deserialize(decoded.as_slice()).map_err(|_| codec::Error)
+            }
+        }
+    };
+}
+
+use crate::{Ciphertext, DecryptionShare, PublicKey, PublicKeySet, Signature};
+
+impl_codec_for!(PublicKey);
+impl_codec_for!(Signature);
+impl_codec_for!(DecryptionShare);
+impl_codec_for!(PublicKeySet);
+impl_codec_for!(Ciphertext);

src/lib.rs

@@ -17,6 +17,10 @@ mod cmp_pairing;
 mod into_fr;
 mod secret;
 
+#[cfg(feature = "codec-support")]
+#[macro_use]
+mod codec_impl;
+
 pub mod error;
 pub mod poly;
 pub mod serde_impl;
@@ -35,17 +39,15 @@ use rand04_compat::RngExt;
 use rand_chacha::ChaChaRng;
 use serde::{Deserialize, Serialize};
 use tiny_keccak::sha3_256;
+use zeroize::Zeroize;
 
 use crate::cmp_pairing::cmp_projective;
 use crate::error::{Error, FromBytesError, FromBytesResult, Result};
 use crate::poly::{Commitment, Poly};
-use crate::secret::{clear_fr, ContainsSecret, MemRange, FR_SIZE};
+use crate::secret::clear_fr;
 
 pub use crate::into_fr::IntoFr;
 
-#[cfg(not(feature = "use-insecure-test-only-mock-crypto"))]
-pub use pairing::bls12_381::{Bls12 as PEngine, Fr, FrRepr, G1Affine, G2Affine, G1, G2};
-
 #[cfg(feature = "use-insecure-test-only-mock-crypto")]
 mod mock;
 
@@ -55,6 +57,9 @@ pub use crate::mock::{
     Ms8Affine as G2Affine, Ms8Projective as G1, Ms8Projective as G2, PK_SIZE, SIG_SIZE,
 };
 
+#[cfg(not(feature = "use-insecure-test-only-mock-crypto"))]
+pub use pairing::bls12_381::{Bls12 as PEngine, Fr, FrRepr, G1Affine, G2Affine, G1, G2};
+
 /// The size of a key's representation in bytes.
 #[cfg(not(feature = "use-insecure-test-only-mock-crypto"))]
 pub const PK_SIZE: usize = 48;
@@ -145,6 +150,7 @@ impl PublicKey {
 }
 
 /// A public key share.
+#[cfg_attr(feature = "codec-support", derive(codec::Encode, codec::Decode))]
 #[derive(Deserialize, Serialize, Clone, Copy, PartialEq, Eq, Hash, Ord, PartialOrd)]
 pub struct PublicKeyShare(PublicKey);
 
@@ -251,6 +257,7 @@ impl Signature {
 
 /// A signature share.
 // Note: Random signature shares can be generated for testing.
+#[cfg_attr(feature = "codec-support", derive(codec::Encode, codec::Decode))]
 #[derive(Deserialize, Serialize, Clone, PartialEq, Eq, Hash, Ord, PartialOrd)]
 pub struct SignatureShare(pub Signature);
 
@@ -290,6 +297,18 @@ impl SignatureShare {
 #[derive(PartialEq, Eq)]
 pub struct SecretKey(Box<Fr>);
 
+impl Zeroize for SecretKey {
+    fn zeroize(&mut self) {
+        clear_fr(&mut *self.0)
+    }
+}
+
+impl Drop for SecretKey {
+    fn drop(&mut self) {
+        self.zeroize();
+    }
+}
+
 /// Creates a `SecretKey` containing the zero prime field element.
 impl Default for SecretKey {
     fn default() -> Self {
@@ -316,13 +335,6 @@ impl Clone for SecretKey {
     }
 }
 
-/// Zeroes out the memory allocated from the `SecretKey`'s field element.
-impl Drop for SecretKey {
-    fn drop(&mut self) {
-        self.zero_secret();
-    }
-}
-
 /// A debug statement where the secret prime field element is redacted.
 impl fmt::Debug for SecretKey {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
@@ -330,15 +342,6 @@ impl fmt::Debug for SecretKey {
     }
 }
 
-impl ContainsSecret for SecretKey {
-    fn secret_memory(&self) -> MemRange {
-        MemRange {
-            ptr: &*self.0 as *const Fr as *mut u8,
-            n_bytes: FR_SIZE,
-        }
-    }
-}
-
 impl SecretKey {
     /// Creates a new `SecretKey` from a mutable reference to a field element. This constructor
     /// takes a reference to avoid any unnecessary stack copying/moving of secrets (i.e. the field
@@ -353,7 +356,7 @@ impl SecretKey {
         unsafe {
             copy_nonoverlapping(fr_ptr, &mut *boxed_fr as *mut Fr, 1);
         }
-        clear_fr(fr_ptr);
+        clear_fr(fr);
         SecretKey(boxed_fr)
     }
 
@@ -1002,9 +1005,7 @@ mod tests {
 
     #[test]
     fn test_serde() {
-        use bincode;
-
-        let sk: SecretKey = random();
+        let sk = SecretKey::random();
         let sig = sk.sign("Please sign here: ______");
         let pk = sk.public_key();
         let ser_pk = bincode::serialize(&pk).expect("serialize public key");
@@ -1017,9 +1018,59 @@ mod tests {
         assert_eq!(sig, deser_sig);
     }
 
+    #[cfg(feature = "codec-support")]
+    #[test]
+    fn test_codec() {
+        use codec::{Decode, Encode};
+        use rand::distributions::{Distribution, Standard};
+        use rand::thread_rng;
+
+        macro_rules! assert_codec {
+            ($obj:expr, $type:ty) => {
+                let encoded: Vec<u8> = $obj.encode();
+                let decoded: $type = <$type>::decode(&mut &encoded[..]).unwrap();
+                assert_eq!(decoded, $obj.clone());
+            };
+        }
+
+        let sk = SecretKey::random();
+        let pk = sk.public_key();
+        assert_codec!(pk, PublicKey);
+
+        let pk_share = PublicKeyShare(pk);
+        assert_codec!(pk_share, PublicKeyShare);
+
+        let sig = sk.sign(b"this is a test");
+        assert_codec!(sig, Signature);
+
+        let sig_share = SignatureShare(sig);
+        assert_codec!(sig_share, SignatureShare);
+
+        let cipher_text = pk.encrypt(b"cipher text");
+        assert_codec!(cipher_text, Ciphertext);
+
+        let dec_share: DecryptionShare = Standard.sample(&mut thread_rng());
+        assert_codec!(dec_share, DecryptionShare);
+
+        let sk_set = SecretKeySet::random(3, &mut thread_rng());
+        let pk_set = sk_set.public_keys();
+        assert_codec!(pk_set, PublicKeySet);
+    }
+
     #[test]
     fn test_size() {
         assert_eq!(<G1Affine as CurveAffine>::Compressed::size(), PK_SIZE);
         assert_eq!(<G2Affine as CurveAffine>::Compressed::size(), SIG_SIZE);
     }
+
+    #[test]
+    fn test_zeroize() {
+        let zero_sk = SecretKey::from_mut(&mut Fr::zero());
+
+        let mut sk = SecretKey::random();
+        assert_ne!(zero_sk, sk);
+
+        sk.zeroize();
+        assert_eq!(zero_sk, sk);
+    }
 }

src/poly.rs

@@ -20,18 +20,18 @@ use std::borrow::Borrow;
 use std::cmp::Ordering;
 use std::fmt::{self, Debug, Formatter};
 use std::hash::{Hash, Hasher};
-use std::mem::size_of_val;
 use std::{cmp, iter, ops};
 
 use pairing::{CurveAffine, CurveProjective, Field};
 use rand::Rng;
 use rand04_compat::RngExt;
 use serde::{Deserialize, Serialize};
+use zeroize::Zeroize;
 
 use crate::cmp_pairing::cmp_projective;
 use crate::error::{Error, Result};
 use crate::into_fr::IntoFr;
-use crate::secret::{clear_fr, ContainsSecret, MemRange, Safe};
+use crate::secret::clear_fr;
 use crate::{Fr, G1Affine, G1};
 
 /// A univariate polynomial in the prime field.
@@ -42,6 +42,20 @@ pub struct Poly {
     pub(super) coeff: Vec<Fr>,
 }
 
+impl Zeroize for Poly {
+    fn zeroize(&mut self) {
+        for fr in self.coeff.iter_mut() {
+            clear_fr(fr)
+        }
+    }
+}
+
+impl Drop for Poly {
+    fn drop(&mut self) {
+        self.zeroize();
+    }
+}
+
 /// Creates a new `Poly` with the same coefficients as another polynomial.
 impl Clone for Poly {
     fn clone(&self) -> Self {
@@ -172,14 +186,15 @@ impl<'a, B: Borrow<Poly>> ops::Mul<B> for &'a Poly {
         }
         let n_coeffs = self.coeff.len() + rhs.coeff.len() - 1;
         let mut coeffs = vec![Fr::zero(); n_coeffs];
-        let mut tmp = Safe::new(Box::new(Fr::zero()));
+        let mut tmp = Fr::zero();
         for (i, ca) in self.coeff.iter().enumerate() {
             for (j, cb) in rhs.coeff.iter().enumerate() {
-                *tmp = *ca;
+                tmp = *ca;
                 tmp.mul_assign(cb);
-                coeffs[i + j].add_assign(&*tmp);
+                coeffs[i + j].add_assign(&tmp);
             }
         }
+        clear_fr(&mut tmp);
         Poly::from(coeffs)
     }
 }
@@ -201,7 +216,7 @@ impl<B: Borrow<Self>> ops::MulAssign<B> for Poly {
 impl ops::MulAssign<Fr> for Poly {
     fn mul_assign(&mut self, rhs: Fr) {
         if rhs.is_zero() {
-            self.zero_secret();
+            self.zeroize();
             self.coeff.clear();
         } else {
             for c in &mut self.coeff {
@@ -216,7 +231,7 @@ impl<'a> ops::Mul<&'a Fr> for Poly {
 
     fn mul(mut self, rhs: &Fr) -> Self::Output {
         if rhs.is_zero() {
-            self.zero_secret();
+            self.zeroize();
             self.coeff.clear();
         } else {
             self.coeff.iter_mut().for_each(|c| c.mul_assign(rhs));
@@ -258,12 +273,6 @@ impl ops::Mul<u64> for Poly {
     }
 }
 
-impl Drop for Poly {
-    fn drop(&mut self) {
-        self.zero_secret();
-    }
-}
-
 /// Creates a new `Poly` instance from a vector of prime field elements representing the
 /// coefficients of the polynomial.
 impl From<Vec<Fr>> for Poly {
@@ -272,14 +281,6 @@ impl From<Vec<Fr>> for Poly {
     }
 }
 
-impl ContainsSecret for Poly {
-    fn secret_memory(&self) -> MemRange {
-        let ptr = self.coeff.as_ptr() as *mut u8;
-        let n_bytes = size_of_val(self.coeff.as_slice());
-        MemRange { ptr, n_bytes }
-    }
-}
-
 impl Poly {
     /// Creates a random polynomial.
     ///
@@ -318,13 +319,12 @@ impl Poly {
     }
 
     /// Returns the polynomial with constant value `c`.
-    pub fn constant(c: Fr) -> Self {
+    pub fn constant(mut c: Fr) -> Self {
         // We create a raw pointer to the field element within this method's stack frame so we can
         // overwrite that portion of memory with zeros once we have copied the element onto the
         // heap as part of the vector of polynomial coefficients.
-        let fr_ptr = &c as *const Fr;
         let poly = Poly::from(vec![c]);
-        clear_fr(fr_ptr);
+        clear_fr(&mut c);
         poly
     }
 
@@ -533,6 +533,21 @@ pub struct BivarPoly {
     coeff: Vec<Fr>,
 }
 
+impl Zeroize for BivarPoly {
+    fn zeroize(&mut self) {
+        for fr in self.coeff.iter_mut() {
+            clear_fr(fr)
+        }
+        self.degree.zeroize();
+    }
+}
+
+impl Drop for BivarPoly {
+    fn drop(&mut self) {
+        self.zeroize();
+    }
+}
+
 impl Clone for BivarPoly {
     fn clone(&self) -> Self {
         BivarPoly {
@@ -542,12 +557,6 @@ impl Clone for BivarPoly {
     }
 }
 
-impl Drop for BivarPoly {
-    fn drop(&mut self) {
-        self.zero_secret();
-    }
-}
-
 /// A debug statement where the `coeff` vector has been redacted.
 impl Debug for BivarPoly {
     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
@@ -558,13 +567,6 @@ impl Debug for BivarPoly {
     }
 }
 
-impl ContainsSecret for BivarPoly {
-    fn secret_memory(&self) -> MemRange {
-        let ptr = self.coeff.as_ptr() as *const Fr as *mut u8;
-        let n_bytes = size_of_val(self.coeff.as_slice());
-        MemRange { ptr, n_bytes }
-    }
-}
 impl BivarPoly {
     /// Creates a random polynomial.
     ///
@@ -769,10 +771,11 @@ mod tests {
     use std::collections::BTreeMap;
 
     use super::{coeff_pos, BivarPoly, IntoFr, Poly};
-
-    use super::{Fr, G1Affine};
-    use pairing::{CurveAffine, Field};
+    use super::{Fr, G1Affine, G1};
+    use pairing::{CurveAffine, CurveProjective, Field};
     use rand;
+    use rand04_compat::RngExt;
+    use zeroize::Zeroize;
 
     #[test]
     fn test_coeff_pos() {
@@ -808,6 +811,25 @@ mod tests {
         assert_eq!(interp, poly);
     }
 
+    #[test]
+    fn test_zeroize() {
+        let mut poly = Poly::monomial(3) + Poly::monomial(2) - 1;
+        poly.zeroize();
+        assert!(poly.is_zero());
+
+        let mut bi_poly = BivarPoly::random(3, &mut rand::thread_rng());
+        let random_commitment = bi_poly.commitment();
+
+        bi_poly.zeroize();
+
+        let zero_commitment = bi_poly.commitment();
+        assert_ne!(random_commitment, zero_commitment);
+
+        let mut rng = rand::thread_rng();
+        let (x, y): (Fr, Fr) = (rng.gen04(), rng.gen04());
+        assert_eq!(zero_commitment.evaluate(x, y), G1::zero());
+    }
+
     #[test]
     fn distributed_key_generation() {
         let mut rng = rand::thread_rng();

src/secret.rs

@@ -1,90 +1,32 @@
 //! Utilities for working with secret values. This module includes functionality for overwriting
 //! memory with zeros.
 
-use std::mem::{size_of, size_of_val};
-use std::ops::{Deref, DerefMut};
+use zeroize::Zeroize;
 
-use memsec::memzero;
-
-use crate::Fr;
-
-pub(crate) const FR_SIZE: usize = size_of::<Fr>();
+use crate::{Fr, FrRepr};
 
 /// Overwrites a single field element with zeros.
-pub(crate) fn clear_fr(fr_ptr: *const Fr) {
-    unsafe { memzero(fr_ptr as *mut u8, FR_SIZE) };
+pub(crate) fn clear_fr(fr: &mut Fr) {
+    // TODO: Remove this after pairing support `Zeroize`
+    let fr_repr = unsafe { &mut *(fr as *mut Fr as *mut FrRepr) };
+    fr_repr.0.zeroize();
 }
 
-pub(crate) struct MemRange {
-    pub ptr: *mut u8,
-    pub n_bytes: usize,
-}
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use pairing::Field;
+    use rand::thread_rng;
+    use rand04_compat::RngExt;
 
-/// Marks a type as containing some secret value.
-pub(crate) trait ContainsSecret {
-    /// Returns the range of memory marked as secret.
-    fn secret_memory(&self) -> MemRange;
+    #[test]
+    fn test_clear() {
+        let mut rng = thread_rng();
 
-    /// Overwrites the secret region of memory with zeros.
-    ///
-    /// This method should be called upon destruction of every type that implements `ContainsSecret`.
-    fn zero_secret(&self) {
-        let MemRange { ptr, n_bytes } = self.secret_memory();
-        unsafe { memzero(ptr, n_bytes) };
-    }
-}
-
-/// A wrapper around temporary values to ensure that they are cleared on drop.
-///
-/// `Safe<T>` is meant to be used a wrapper around `T`, where `T` is  either an `&mut U` or
-/// `Box<U>`.
-pub(crate) struct Safe<T: DerefMut>(T);
-
-impl<T> Deref for Safe<T>
-where
-    T: DerefMut,
-{
-    type Target = T::Target;
-
-    fn deref(&self) -> &Self::Target {
-        &*(self.0)
-    }
-}
-
-impl<T> DerefMut for Safe<T>
-where
-    T: DerefMut,
-{
-    fn deref_mut(&mut self) -> &mut Self::Target {
-        &mut *(self.0)
-    }
-}
-
-impl<T> Drop for Safe<T>
-where
-    T: DerefMut,
-{
-    fn drop(&mut self) {
-        self.zero_secret();
-    }
-}
-
-impl<T> ContainsSecret for Safe<T>
-where
-    T: DerefMut,
-{
-    fn secret_memory(&self) -> MemRange {
-        let ptr = &*self.0 as *const T::Target as *mut u8;
-        let n_bytes = size_of_val(&*self.0);
-        MemRange { ptr, n_bytes }
-    }
-}
-
-impl<T> Safe<T>
-where
-    T: DerefMut,
-{
-    pub(crate) fn new(x: T) -> Self {
-        Safe(x)
+        let mut fr: Fr = rng.gen04();
+        assert_ne!(fr, Fr::zero());
+
+        clear_fr(&mut fr);
+        assert_eq!(fr, Fr::zero());
     }
 }