Zeroize secret keys upon drop

.changelog/unreleased/improvements/277-zeroize-secret-keys.md

@@ -0,0 +1,2 @@
+- Zeroize secret keys from memory
+  ([#277](https://github.com/anoma/namada/pull/277))

shared/Cargo.toml

@@ -116,6 +116,7 @@ wasmer-engine-dylib = {version = "=2.2.0", optional = true}
 wasmer-engine-universal = {version = "=2.2.0", optional = true}
 wasmer-vm = {version = "2.2.0", optional = true}
 wasmparser = "0.83.0"
+zeroize = "1.5.5"
 
 [dev-dependencies]
 assert_matches = "1.5.0"

shared/src/types/key/ed25519.rs

@@ -9,6 +9,7 @@ use borsh::{BorshDeserialize, BorshSchema, BorshSerialize};
 #[cfg(feature = "rand")]
 use rand::{CryptoRng, RngCore};
 use serde::{Deserialize, Serialize};
+use zeroize::Zeroize;
 
 use super::{
     ParsePublicKeyError, ParseSecretKeyError, ParseSignatureError, RefTo,
@@ -122,8 +123,8 @@ impl FromStr for PublicKey {
 }
 
 /// Ed25519 secret key
-#[derive(Debug, Serialize, Deserialize)]
-pub struct SecretKey(pub ed25519_consensus::SigningKey);
+#[derive(Debug, Serialize, Deserialize, Zeroize)]
+pub struct SecretKey(pub Box<ed25519_consensus::SigningKey>);
 
 impl super::SecretKey for SecretKey {
     type PublicKey = PublicKey;
@@ -157,13 +158,15 @@ impl RefTo<PublicKey> for SecretKey {
 
 impl Clone for SecretKey {
     fn clone(&self) -> SecretKey {
-        SecretKey(ed25519_consensus::SigningKey::from(self.0.to_bytes()))
+        SecretKey(Box::new(ed25519_consensus::SigningKey::from(
+            self.0.to_bytes(),
+        )))
     }
 }
 
 impl BorshDeserialize for SecretKey {
     fn deserialize(buf: &mut &[u8]) -> std::io::Result<Self> {
-        Ok(SecretKey(
+        Ok(SecretKey(Box::new(
             ed25519_consensus::SigningKey::try_from(
                 <[u8; SECRET_KEY_LENGTH] as BorshDeserialize>::deserialize(
                     buf,
@@ -173,7 +176,7 @@ impl BorshDeserialize for SecretKey {
             .map_err(|e| {
                 std::io::Error::new(std::io::ErrorKind::InvalidInput, e)
             })?,
-        ))
+        )))
     }
 }
 
@@ -218,6 +221,12 @@ 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);
@@ -325,7 +334,7 @@ impl super::SigScheme for SigScheme {
     where
         R: CryptoRng + RngCore,
     {
-        SecretKey(ed25519_consensus::SigningKey::new(csprng))
+        SecretKey(Box::new(ed25519_consensus::SigningKey::new(csprng)))
     }
 
     fn sign(keypair: &SecretKey, data: impl AsRef<[u8]>) -> Self::Signature {

shared/src/types/key/mod.rs

@@ -421,3 +421,25 @@ macro_rules! sigscheme_test {
 
 #[cfg(test)]
 sigscheme_test! {ed25519_test, ed25519::SigScheme}
+
+#[cfg(test)]
+mod more_tests {
+    use super::*;
+
+    #[test]
+    fn zeroize_keypair_ed25519() {
+        use rand::thread_rng;
+
+        let sk = ed25519::SecretKey(Box::new(
+            ed25519_consensus::SigningKey::new(thread_rng()),
+        ));
+        let len = sk.0.as_bytes().len();
+        let ptr = sk.0.as_bytes().as_ptr();
+
+        drop(sk);
+
+        assert_eq!(&[0u8; 32], unsafe {
+            core::slice::from_raw_parts(ptr, len)
+        });
+    }
+}

wasm/checksums.json

@@ -1,19 +1,19 @@
 {
-    "tx_bond.wasm": "tx_bond.302172cc7d0a7e2278ce58299809875f354925364b25c9b64e92461995c51950.wasm",
-    "tx_from_intent.wasm": "tx_from_intent.19099ad11a5f59272bd5dbd8b7bc7093ae66ae7a2b25034300f1b34d3e37ffd1.wasm",
-    "tx_ibc.wasm": "tx_ibc.9aec1969a37705f9ae5d6e95d13126e0f37e78171ef37c2f0fdd0eb16ac49270.wasm",
-    "tx_init_account.wasm": "tx_init_account.7a45233a98978c67ff005bf8a1fb8f3f7689a75f98684c1735617776f98fabad.wasm",
-    "tx_init_nft.wasm": "tx_init_nft.b0dd29e0e982c3bd04c7a8c4dcd0184d9d827df6a4211794dd74fbdced1e7430.wasm",
-    "tx_init_proposal.wasm": "tx_init_proposal.45be75dc2c22048dce23ae346c895b2be19737a39844416436aac62914847388.wasm",
-    "tx_init_validator.wasm": "tx_init_validator.5a7c9a3a115883359246a4145af11f748ded043b5b36d1cb71e54fb3ef169183.wasm",
-    "tx_mint_nft.wasm": "tx_mint_nft.fd8932515db71638263193930f60c14cec54c11e72e6ab40d8201d0247db0c1a.wasm",
-    "tx_transfer.wasm": "tx_transfer.9e51e5b48ba3ddee699fed334e14fe9a81b7e299b0cfcbf10482b9f784c092c2.wasm",
-    "tx_unbond.wasm": "tx_unbond.020d22fa306850b0a4aade96f711087d03568ed45276fff60226a80de47cc455.wasm",
-    "tx_update_vp.wasm": "tx_update_vp.00d828bdf510d92d971ca59015945c8c00f285a802a655451cc5ee87c5ee99bc.wasm",
-    "tx_vote_proposal.wasm": "tx_vote_proposal.b8aa22d6d22c31fa6c1f4619a81eaa43aa40c8865b91f71449a5f3c65b84eacf.wasm",
-    "tx_withdraw.wasm": "tx_withdraw.b8538e5acfc2945e98b76cc17eb11a03c545021e8f70cf6e5b436219e749b559.wasm",
-    "vp_nft.wasm": "vp_nft.d272e0c50f17c020fe806e03278e83377ec45b81e88432316ce836ee24605f6e.wasm",
-    "vp_testnet_faucet.wasm": "vp_testnet_faucet.79c1da702d67f464453af0b145872bba28913b029508f1257b4a22f69123ec1e.wasm",
-    "vp_token.wasm": "vp_token.04482a8132e91ab726b4a9027f44a84c885c36e3d608e9c4e153d0cfe4f88449.wasm",
-    "vp_user.wasm": "vp_user.e390d55fc2e797fcc4c43bd40b93ea1c3d58544d5f086301a0dbc38bd93388ba.wasm"
+    "tx_bond.wasm": "tx_bond.e8fcf7413067810f82e1c0f54fdc9675a4c686b172db9c44c714310d3f19baf6.wasm",
+    "tx_from_intent.wasm": "tx_from_intent.cd5f7af4d3af9300df8dc16e891f39f85d6497a43a2cd74d30d1dc506649291e.wasm",
+    "tx_ibc.wasm": "tx_ibc.3805f69ceafd60b857a860d26e6fbe2973f309289147cf59c10e0bd65a30057e.wasm",
+    "tx_init_account.wasm": "tx_init_account.8abb68c5f40fa9ea39f03ddb9c387bc84a642bac4f40c7e9ceebb8418b3ccde7.wasm",
+    "tx_init_nft.wasm": "tx_init_nft.564390006d7b8f4f46d215704b05561a7279c92a6fe8f3ec61118a5486a3e092.wasm",
+    "tx_init_proposal.wasm": "tx_init_proposal.5fc912c847cb4d04743b4dea650418a4eae233f4abf91493791a92e3de5050aa.wasm",
+    "tx_init_validator.wasm": "tx_init_validator.92d11bc1cc27818864e13d122179a199043a274f7bba901b11c6474261eb97eb.wasm",
+    "tx_mint_nft.wasm": "tx_mint_nft.9f5b723dd4ed195b489b8456a6d83167829f0b2b8fb479be19b877a60b81c803.wasm",
+    "tx_transfer.wasm": "tx_transfer.032bfa997c8f2ee2cc5bf053f0128880a79a57ad3d8c3ecc6ff0c22e27f47ebd.wasm",
+    "tx_unbond.wasm": "tx_unbond.17444d665b8a7bebb624691eaab318c845c8ce18c557d0af440b7bfdb7efa806.wasm",
+    "tx_update_vp.wasm": "tx_update_vp.d47bfe6ef55a86bce36093feeff74fe09ec7cffebf9696dd37658756a4eb793d.wasm",
+    "tx_vote_proposal.wasm": "tx_vote_proposal.1bee09ffd3a1e577dc9b9d6d5f91c4a6f91a9b2ac9e3a3d8258c00cd12902304.wasm",
+    "tx_withdraw.wasm": "tx_withdraw.75dbdc78924d8072ffcefaed67715d9480dd9f702ac77cf18ee15d0e44a38ab0.wasm",
+    "vp_nft.wasm": "vp_nft.3711eac06bda0c39ab52618bc458df7e6b16ed096bb3930b93ade93c9b7cf23a.wasm",
+    "vp_testnet_faucet.wasm": "vp_testnet_faucet.400be39dcf0fedf099232bdecfa42c2dbe1f0aaede34fb99ec26da3b6623c09a.wasm",
+    "vp_token.wasm": "vp_token.118aef31933858351cf77315069fc2f7c61e7db8891c7990e77f9ffd6ef90af0.wasm",
+    "vp_user.wasm": "vp_user.73136ffcd68e46e2f88d27ae9e48a0731b06d883dd3defcb41b604cc7968c638.wasm"
 }