Remove dependency on curv in multisig (#1819)

* chore: move import inside macro

* chore: remove curv dependency

* chore: correct file name

* add missing word in comment

* fix zero substraction

* address minor comments

Co-authored-by: Alastair Holmes <holmes.alastair@outlook.com>

engine/Cargo.toml

@@ -47,7 +47,7 @@ lazy_static = "1.4"
 parking_lot = "0.12"
 regex = "1"
 reqwest = {version = "0.11.4", features = ["json"]}
-secp256k1 = "0.20"
+secp256k1 = {version = "0.20", features = ["serde", "rand-std", "global-context"]}
 serde = {version = "1.0", features = ["derive", "rc"]}
 serde_json = "1.0"
 sha2 = "0.9.5"
@@ -58,6 +58,8 @@ thiserror = "1.0.26"
 tokio = {version = "1.13.1", features = ["full"]}
 tokio-stream = "0.1.5"
 url = "1.7.2"
+num-bigint = "0.4"
+num-traits = "0.2"
 web3 = {git = 'https://github.com/tomusdrw/rust-web3.git', rev = '8796c88', features = ['signing']}
 zeroize = "1.5.4"
 libp2p = "0.40"
@@ -150,9 +152,6 @@ tag = 'chainflip-monthly-2022-05'
 git = 'https://github.com/chainflip-io/substrate.git'
 tag = 'chainflip-monthly-2022-05'
 
-[dependencies.curv-kzen]
-version = "0.9"
-
 [dev-dependencies]
 env_logger = "0.9.0"
 jsonrpc-pubsub = "18.0.0"

engine/src/multisig/client/keygen/keygen_frost.rs

@@ -101,7 +101,7 @@ fn generate_dkg_challenge<P: ECPoint>(
 
     let x: [u8; 32] = result.as_slice().try_into().expect("Invalid hash size");
 
-    P::Scalar::from_bytes(&x)
+    P::Scalar::from_bytes_mod_order(&x)
 }
 
 /// Generate ZKP (zero-knowledge proof) of `secret`

engine/src/multisig/client/signing/frost.rs

@@ -200,7 +200,7 @@ fn gen_rho_i<P: ECPoint>(
 
     let x: [u8; 32] = result.as_slice().try_into().expect("Invalid hash size");
 
-    P::Scalar::from_bytes(&x)
+    P::Scalar::from_bytes_mod_order(&x)
 }
 
 type SigningResponse<P> = LocalSig3<P>;

engine/src/multisig/crypto.rs

@@ -3,11 +3,10 @@ mod helpers;
 pub mod curve25519_ristretto;
 pub mod eth;
 pub mod polkadot;
-pub mod secp255k1;
+pub mod secp256k1;
 
 use generic_array::{typenum::Unsigned, ArrayLength};
 
-pub use curv::{arithmetic::traits::Converter as BigIntConverter, BigInt};
 use zeroize::{DefaultIsZeroes, ZeroizeOnDrop};
 
 use std::fmt::Debug;
@@ -79,6 +78,10 @@ pub trait ECPoint:
     }
 
     // Only relevant for ETH contract keys
+    // TODO: this is a property of a signing scheme
+    // rather than the underlying curve, so this
+    // should be moved to `CryptoScheme` before we
+    // add Bitcoin or any other secp256k1 scheme
     fn is_compatible(&self) -> bool {
         true
     }
@@ -142,7 +145,7 @@ pub trait ECScalar:
 {
     fn random(rng: &mut Rng) -> Self;
 
-    fn from_bytes(x: &[u8; 32]) -> Self;
+    fn from_bytes_mod_order(x: &[u8; 32]) -> Self;
 
     fn zero() -> Self;
 

engine/src/multisig/crypto/curve25519_ristretto.rs

@@ -70,7 +70,7 @@ mod point_impls {
 
 mod scalar_impls {
 
-    use zeroize::{Zeroize, ZeroizeOnDrop};
+    use zeroize::Zeroize;
 
     use super::*;
 
@@ -88,7 +88,7 @@ mod scalar_impls {
             Scalar(SK::from_bytes_mod_order_wide(&scalar_bytes))
         }
 
-        fn from_bytes(x: &[u8; 32]) -> Self {
+        fn from_bytes_mod_order(x: &[u8; 32]) -> Self {
             Scalar(SK::from_bytes_mod_order(*x))
         }
 

engine/src/multisig/crypto/eth.rs

@@ -6,7 +6,7 @@ use super::{ChainTag, CryptoScheme, ECPoint};
 // clear that these a the primitives used by ethereum.
 // TODO: we probably want to change the "clients" to
 // solely use "CryptoScheme" as generic parameter instead.
-pub use super::secp255k1::{Point, Scalar};
+pub use super::secp256k1::{Point, Scalar};
 use serde::{Deserialize, Serialize};
 
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
@@ -59,7 +59,7 @@ impl CryptoScheme for EthSigning {
             &pubkey_to_eth_addr(nonce_commitment.get_element()),
         );
 
-        Scalar::from_bytes(&e)
+        Scalar::from_bytes_mod_order(&e)
     }
 
     fn build_response(

engine/src/multisig/crypto/helpers.rs

@@ -8,11 +8,12 @@ macro_rules! derive_scalar_impls {
 
         impl Drop for $scalar {
             fn drop(&mut self) {
+                use zeroize::Zeroize;
                 self.zeroize();
             }
         }
 
-        impl ZeroizeOnDrop for $scalar {}
+        impl zeroize::ZeroizeOnDrop for $scalar {}
 
         impl std::ops::Add for $scalar {
             type Output = $scalar;