Add ZeroizeOnDrop to ed25519 keys

.changelog/unreleased/miscellaneous/1958-k256.md

@@ -0,0 +1,2 @@
+- Switched from using `libsecp256k1` to `k256` crate.
+  ([\#1958](https://github.com/anoma/namada/pull/1958))

.changelog/unreleased/miscellaneous/1958-zeroize-secret-keys.md

@@ -0,0 +1,2 @@
+- Tag `ed25519` keys with `ZeroizeOnDrop`
+  ([\#1958](https://github.com/anoma/namada/pull/1958))

Cargo.toml

@@ -85,10 +85,10 @@ git2 = "0.13.25"
 ics23 = "0.9.0"
 index-set = {git = "https://github.com/heliaxdev/index-set", tag = "v0.7.1", features = ["serialize-borsh", "serialize-serde"]}
 itertools = "0.10.0"
+k256 = { version = "0.13.0", default-features = false, features = ["ecdsa", "pkcs8", "precomputed-tables", "serde", "std"]}
 lazy_static = "1.4.0"
 libc = "0.2.97"
 libloading = "0.7.2"
-libsecp256k1 = {git = "https://github.com/heliaxdev/libsecp256k1", rev = "bbb3bd44a49db361f21d9db80f9a087c194c0ae9", default-features = false, features = ["std", "static-context"]}
 # branch = "murisi/namada-integration"
 masp_primitives = { git = "https://github.com/anoma/masp", rev = "50acc5028fbcd52a05970fe7991c7850ab04358e" }
 masp_proofs = { git = "https://github.com/anoma/masp", rev = "50acc5028fbcd52a05970fe7991c7850ab04358e", default-features = false, features = ["local-prover"] }

apps/src/lib/node/ledger/shell/mod.rs

@@ -1612,11 +1612,11 @@ mod test_utils {
                 ref sig,
                 ref recovery_id,
             )) => {
-                let mut sig_bytes = sig.serialize();
-                let recovery_id_bytes = recovery_id.serialize();
+                let mut sig_bytes = sig.to_vec();
+                let recovery_id_bytes = recovery_id.to_byte();
                 sig_bytes[0] = sig_bytes[0].wrapping_add(1);
                 let bytes: [u8; 65] =
-                    [sig_bytes.as_slice(), [recovery_id_bytes].as_slice()]
+                    [sig_bytes.as_slice(), &[recovery_id_bytes]]
                         .concat()
                         .try_into()
                         .unwrap();

core/Cargo.toml

@@ -25,11 +25,6 @@ ferveo-tpke = [
 wasm-runtime = [
   "rayon",
 ]
-# secp256k1 key signing, disabled in WASM build by default as it bloats the 
-# build a lot
-secp256k1-sign = [
-  "libsecp256k1/hmac",
-]
 
 abciplus = [
   "ibc",
@@ -78,7 +73,7 @@ ics23.workspace = true
 impl-num-traits = "0.1.2"
 index-set.workspace = true
 itertools.workspace = true
-libsecp256k1.workspace = true
+k256.workspace = true
 masp_primitives.workspace = true
 num256.workspace = true
 num-integer = "0.1.45"
@@ -104,7 +99,6 @@ zeroize.workspace = true
 
 [dev-dependencies]
 assert_matches.workspace = true
-libsecp256k1 = {workspace = true, features = ["hmac"]}
 pretty_assertions.workspace = true
 proptest.workspace = true
 rand.workspace = true

core/src/types/key/ed25519.rs

@@ -10,7 +10,7 @@ use data_encoding::HEXLOWER;
 #[cfg(feature = "rand")]
 use rand::{CryptoRng, RngCore};
 use serde::{Deserialize, Serialize};
-use zeroize::Zeroize;
+use zeroize::{Zeroize, ZeroizeOnDrop};
 
 use super::{
     ParsePublicKeyError, ParseSecretKeyError, ParseSignatureError, RefTo,
@@ -125,7 +125,7 @@ impl FromStr for PublicKey {
 }
 
 /// Ed25519 secret key
-#[derive(Debug, Serialize, Deserialize, Zeroize)]
+#[derive(Debug, Serialize, Deserialize, Zeroize, ZeroizeOnDrop)]
 pub struct SecretKey(pub Box<ed25519_consensus::SigningKey>);
 
 impl super::SecretKey for SecretKey {
@@ -223,12 +223,6 @@ impl FromStr for SecretKey {
     }
 }
 
-impl Drop for SecretKey {
-    fn drop(&mut self) {
-        self.0.zeroize();
-    }
-}
-
 /// Ed25519 signature
 #[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
 pub struct Signature(pub ed25519_consensus::Signature);

core/src/types/key/mod.rs

@@ -692,17 +692,15 @@ mod more_tests {
     fn zeroize_keypair_secp256k1() {
         use rand::thread_rng;
 
-        let mut sk = secp256k1::SigScheme::generate(&mut thread_rng());
-        let sk_scalar = sk.0.to_scalar_ref();
-        let len = sk_scalar.0.len();
-        let ptr = sk_scalar.0.as_ref().as_ptr();
-
-        let original_data = sk_scalar.0;
-
+        let sk = secp256k1::SigScheme::generate(&mut thread_rng());
+        let (ptr, original_data) = {
+            let sk_scalar = sk.0.as_scalar_primitive().as_ref();
+            (sk_scalar.as_ptr(), sk_scalar.to_owned())
+        };
         drop(sk);
 
-        assert_ne!(&original_data, unsafe {
-            core::slice::from_raw_parts(ptr, len)
+        assert_ne!(original_data.as_slice(), unsafe {
+            core::slice::from_raw_parts(ptr, secp256k1::SECRET_KEY_SIZE)
         });
     }
 }